1

City UniversityDhakaBangladesh

Assignment OnTypes of Diodehelliphellip

Cource titleElectronic Circuit I

Cource Code EEE301 Submitted by Robioul AwalID153103022

Batch10th

FacebookbcomRobioul999

2

Submission date7-02-2017

What is a Diodehelliphelliphellip

A Diode is the simplest two-terminal unilateral semiconductor device It allows current to flow only in one direction and blocks the current that flows in the opposite direction The two terminals of the diode are called as anode and cathode The symbol of diode is as shown in the figure below

characteristics of a diode

How Diodes workhellipThe diode operates when a voltage signal is applied across its terminals The application of a DC voltage to make the diode operate in a circuit is called as lsquoBiasingrsquo As already mentioned above the diode resembles to that of a one way switch so it can either be in a state of conduction or in a state of non conduction The lsquoONrsquo state of a diode is achieved by lsquoForward biasingrsquo which means that positive or higher potential is applied to the anode and negative or lower potential is applied at the cathode of the diode In other words the lsquoONrsquo state of diode has the applied current in the same direction of the arrow head The lsquoOFFrsquo state of a diode is achieved by lsquoReverse biasingrsquo which means that positive or higher potential is applied to the cathode and negative or lower potential is applied at the anode of the diode In other words the lsquoOFFrsquo state of diode has the applied current in the opposite direction of the arrow head

During lsquoONrsquo state the practical diode offers a resistance called as the lsquoForward resistancersquo The diode requires a forward bias voltage to switch to the lsquoONrsquo condition which is called Cut-in-voltage The diode starts conducting in reverse biased mode when the reverse bias voltage exceeds its limit which is called as the Breakdown voltage The diode remains in lsquoOFFrsquo state when no voltage is applied across it

3

A simple p-n juction diode is fabricated by doping p and n type layers on a silicon or germanium wafer The germanium and silicon materials are prefered for diode fabrication becausemiddot They are available in high purity Slight doping like one atom per ten million atoms of a desired impurity can change the conductivity to a considerable level The properties of these materials change on applying heat and light and hence it is important in the devlopment of heat and light sensetive devices

Types of Diode The types of diode are as follow-

1 Zener diode2 P-N junction diode3 Tunnel diode4 Varactor diode5 Schottky diode6 Photo diode7 PIN diode8 Laser diode9 Avalanche diode10Light emitting diode

1Zener diodes Zener diodes are semiconductor diodes which have been manufactured to have their reverse breakdown occur at a specific well-defined voltage (its ldquoZener voltagerdquo) and that are designed such that they can be operated continuously in that breakdown mode Commonly available Zener diodes are available with breakdown voltages (ldquoZener voltagesrdquo) anywhere from 18 to 200 V

4

The schematic symbol for a Zener diode is shown abovendash it is very similar to that of a regular diode but with bent edges on the bar The Zener still conducts electricity in the forward direction like any other diode but also conducts in the reverse direction if the voltage applied is reversed and larger than the Zener breakdown voltage

V-I characteristicsThe V-I Characteristics of a Zener Diode can be divided into two parts

Forward Characteristics

Reverse Characteristics

2

Submission date7-02-2017

What is a Diodehelliphelliphellip

A Diode is the simplest two-terminal unilateral semiconductor device It allows current to flow only in one direction and blocks the current that flows in the opposite direction The two terminals of the diode are called as anode and cathode The symbol of diode is as shown in the figure below

characteristics of a diode

How Diodes workhellipThe diode operates when a voltage signal is applied across its terminals The application of a DC voltage to make the diode operate in a circuit is called as lsquoBiasingrsquo As already mentioned above the diode resembles to that of a one way switch so it can either be in a state of conduction or in a state of non conduction The lsquoONrsquo state of a diode is achieved by lsquoForward biasingrsquo which means that positive or higher potential is applied to the anode and negative or lower potential is applied at the cathode of the diode In other words the lsquoONrsquo state of diode has the applied current in the same direction of the arrow head The lsquoOFFrsquo state of a diode is achieved by lsquoReverse biasingrsquo which means that positive or higher potential is applied to the cathode and negative or lower potential is applied at the anode of the diode In other words the lsquoOFFrsquo state of diode has the applied current in the opposite direction of the arrow head

During lsquoONrsquo state the practical diode offers a resistance called as the lsquoForward resistancersquo The diode requires a forward bias voltage to switch to the lsquoONrsquo condition which is called Cut-in-voltage The diode starts conducting in reverse biased mode when the reverse bias voltage exceeds its limit which is called as the Breakdown voltage The diode remains in lsquoOFFrsquo state when no voltage is applied across it

3

A simple p-n juction diode is fabricated by doping p and n type layers on a silicon or germanium wafer The germanium and silicon materials are prefered for diode fabrication becausemiddot They are available in high purity Slight doping like one atom per ten million atoms of a desired impurity can change the conductivity to a considerable level The properties of these materials change on applying heat and light and hence it is important in the devlopment of heat and light sensetive devices

Types of Diode The types of diode are as follow-

1 Zener diode2 P-N junction diode3 Tunnel diode4 Varactor diode5 Schottky diode6 Photo diode7 PIN diode8 Laser diode9 Avalanche diode10Light emitting diode

1Zener diodes Zener diodes are semiconductor diodes which have been manufactured to have their reverse breakdown occur at a specific well-defined voltage (its ldquoZener voltagerdquo) and that are designed such that they can be operated continuously in that breakdown mode Commonly available Zener diodes are available with breakdown voltages (ldquoZener voltagesrdquo) anywhere from 18 to 200 V

4

The schematic symbol for a Zener diode is shown abovendash it is very similar to that of a regular diode but with bent edges on the bar The Zener still conducts electricity in the forward direction like any other diode but also conducts in the reverse direction if the voltage applied is reversed and larger than the Zener breakdown voltage

V-I characteristicsThe V-I Characteristics of a Zener Diode can be divided into two parts

Forward Characteristics

Reverse Characteristics

3

A simple p-n juction diode is fabricated by doping p and n type layers on a silicon or germanium wafer The germanium and silicon materials are prefered for diode fabrication becausemiddot They are available in high purity Slight doping like one atom per ten million atoms of a desired impurity can change the conductivity to a considerable level The properties of these materials change on applying heat and light and hence it is important in the devlopment of heat and light sensetive devices

Types of Diode The types of diode are as follow-

1 Zener diode2 P-N junction diode3 Tunnel diode4 Varactor diode5 Schottky diode6 Photo diode7 PIN diode8 Laser diode9 Avalanche diode10Light emitting diode

1Zener diodes Zener diodes are semiconductor diodes which have been manufactured to have their reverse breakdown occur at a specific well-defined voltage (its ldquoZener voltagerdquo) and that are designed such that they can be operated continuously in that breakdown mode Commonly available Zener diodes are available with breakdown voltages (ldquoZener voltagesrdquo) anywhere from 18 to 200 V

4

The schematic symbol for a Zener diode is shown abovendash it is very similar to that of a regular diode but with bent edges on the bar The Zener still conducts electricity in the forward direction like any other diode but also conducts in the reverse direction if the voltage applied is reversed and larger than the Zener breakdown voltage

V-I characteristicsThe V-I Characteristics of a Zener Diode can be divided into two parts

Forward Characteristics

Reverse Characteristics

4

The schematic symbol for a Zener diode is shown abovendash it is very similar to that of a regular diode but with bent edges on the bar The Zener still conducts electricity in the forward direction like any other diode but also conducts in the reverse direction if the voltage applied is reversed and larger than the Zener breakdown voltage

V-I characteristicsThe V-I Characteristics of a Zener Diode can be divided into two parts

Forward Characteristics

Reverse Characteristics

5

Advantages amp DisadvantagesAdvantages

Control of flowing current

Size and Expense

Performance

Compatibility and Obtainability

DisadvantagesZener diodes cancel out voltages by applying even larger voltages in the reverse

6

direction wasting electricity in the process Additionally Zener diodes have a relatively poor regulation ratio and are generally not as good as transistors

2Tunnel Diode

IV CharacteristicsAs forward bias is applied significant I is produced

After continuous increase of V the current achieves its minimum value called as Valley Current After further increase in V current start increasing as ordinary diode

7

Advantage

1 environmental immunity2 Low cost3 Simplicity4 Low noise5 High speed6 Low power consumption

Disadvantage

Only disadvantage of tunnel diode are its low output voltage swing and it is a two terminal device hence there is no isolation between input and output hence transistor is used along with a tunnel diode for frequencies below 1 GHz

3Varactor diode

Varactor Diode is a reverse biased p-n junction diode whose capacitance can be varied electrically As a result these diodes are also referred to as varicaps tuning diodes voltage variable

8

capacitor diodes parametric diodes and variable capacitor diodes

Characteristics1Low-noise characteristic produce much less noise than most conventional amplifiers2Low Cost3High Realibity4Light Weath

5Small Size

Advantage It is basically an electrically controlled variable capacitor no moving parts needa monitored voltage source to hold the value temperature sensitive Si based

Disadvantagedont work over 100C variable capacitors in the mechanical adjusted variety work with higher voltages arent voltage spike sensitive and are far more rugged are in picofarad to micro farad range can handle many kilowatts set and forget dont need controls to maintain capacitance arent temperature sensitive can be motor driven for electric control

4 Schottky diode

Schottky diode it is also referred to as Schottky barrier diode or as hot carrier diode This is a diode with semiconductor-metal junction This device can simply rectify frequencies greater than 300 MHz Its forward

9

voltage drop is also very low (015 to 045 V) This results in higher switching speed and improved system efficiency The junction in the diode is formed by the metal (such as gold tungsten chromium platinum molybdenum or certain silicides) and N-type doped silicon semiconductor

V-I characteristics of Schottky Diode

Schottky diode I-V characteristicsSchottky diode is a metal-semiconductor (MS) diodeHistorically Schottky diodes are the oldest diodesMS diode electrostatics and the general shape of the MS diode I-V characteristics are similar to p+n diodes but the details of current flow are different Dominant currents in a p+n diodearise from recombination in the depletion layer under small forward biasarise from hole injection from p+ side under larger forward biasDominant currents in a MS Schottky diodesElectron injection from the semiconductor to the metal

Advantages

7

Advantage

1 environmental immunity2 Low cost3 Simplicity4 Low noise5 High speed6 Low power consumption

Disadvantage

Only disadvantage of tunnel diode are its low output voltage swing and it is a two terminal device hence there is no isolation between input and output hence transistor is used along with a tunnel diode for frequencies below 1 GHz

3Varactor diode

Varactor Diode is a reverse biased p-n junction diode whose capacitance can be varied electrically As a result these diodes are also referred to as varicaps tuning diodes voltage variable

8

capacitor diodes parametric diodes and variable capacitor diodes

Characteristics1Low-noise characteristic produce much less noise than most conventional amplifiers2Low Cost3High Realibity4Light Weath

5Small Size

Advantage It is basically an electrically controlled variable capacitor no moving parts needa monitored voltage source to hold the value temperature sensitive Si based

Disadvantagedont work over 100C variable capacitors in the mechanical adjusted variety work with higher voltages arent voltage spike sensitive and are far more rugged are in picofarad to micro farad range can handle many kilowatts set and forget dont need controls to maintain capacitance arent temperature sensitive can be motor driven for electric control

4 Schottky diode

Schottky diode it is also referred to as Schottky barrier diode or as hot carrier diode This is a diode with semiconductor-metal junction This device can simply rectify frequencies greater than 300 MHz Its forward

9

voltage drop is also very low (015 to 045 V) This results in higher switching speed and improved system efficiency The junction in the diode is formed by the metal (such as gold tungsten chromium platinum molybdenum or certain silicides) and N-type doped silicon semiconductor

V-I characteristics of Schottky Diode

Schottky diode I-V characteristicsSchottky diode is a metal-semiconductor (MS) diodeHistorically Schottky diodes are the oldest diodesMS diode electrostatics and the general shape of the MS diode I-V characteristics are similar to p+n diodes but the details of current flow are different Dominant currents in a p+n diodearise from recombination in the depletion layer under small forward biasarise from hole injection from p+ side under larger forward biasDominant currents in a MS Schottky diodesElectron injection from the semiconductor to the metal

Advantages

8

capacitor diodes parametric diodes and variable capacitor diodes

Characteristics1Low-noise characteristic produce much less noise than most conventional amplifiers2Low Cost3High Realibity4Light Weath

5Small Size

Advantage It is basically an electrically controlled variable capacitor no moving parts needa monitored voltage source to hold the value temperature sensitive Si based

Disadvantagedont work over 100C variable capacitors in the mechanical adjusted variety work with higher voltages arent voltage spike sensitive and are far more rugged are in picofarad to micro farad range can handle many kilowatts set and forget dont need controls to maintain capacitance arent temperature sensitive can be motor driven for electric control

4 Schottky diode

Schottky diode it is also referred to as Schottky barrier diode or as hot carrier diode This is a diode with semiconductor-metal junction This device can simply rectify frequencies greater than 300 MHz Its forward

9

voltage drop is also very low (015 to 045 V) This results in higher switching speed and improved system efficiency The junction in the diode is formed by the metal (such as gold tungsten chromium platinum molybdenum or certain silicides) and N-type doped silicon semiconductor

V-I characteristics of Schottky Diode

Schottky diode I-V characteristicsSchottky diode is a metal-semiconductor (MS) diodeHistorically Schottky diodes are the oldest diodesMS diode electrostatics and the general shape of the MS diode I-V characteristics are similar to p+n diodes but the details of current flow are different Dominant currents in a p+n diodearise from recombination in the depletion layer under small forward biasarise from hole injection from p+ side under larger forward biasDominant currents in a MS Schottky diodesElectron injection from the semiconductor to the metal

Advantages

9

voltage drop is also very low (015 to 045 V) This results in higher switching speed and improved system efficiency The junction in the diode is formed by the metal (such as gold tungsten chromium platinum molybdenum or certain silicides) and N-type doped silicon semiconductor

V-I characteristics of Schottky Diode

Schottky diode I-V characteristicsSchottky diode is a metal-semiconductor (MS) diodeHistorically Schottky diodes are the oldest diodesMS diode electrostatics and the general shape of the MS diode I-V characteristics are similar to p+n diodes but the details of current flow are different Dominant currents in a p+n diodearise from recombination in the depletion layer under small forward biasarise from hole injection from p+ side under larger forward biasDominant currents in a MS Schottky diodesElectron injection from the semiconductor to the metal

Advantages

10

DisadvantageshellipLimitations The most evident limitations of Schottky diodes are the relatively low reverse voltage ratings for silicon-metal Schottky diodes typically 50 V and below and a relatively high reverse leakage current Some higher-voltage designs are available 200V is considered a high reverse voltageReverse leakage current because it increases with temperature leads to a thermal instability issue This often limits the useful reverse voltage to well below the actual ratingWhile higher reverse voltages are achievable they would be accompanied by higher forward voltage drops comparable to other types such a Schottky diode would have no advantage

5Photodiode

11

A photodiode is one type of light detector used to convert the light into current or voltage based on the mode of operation of the device

It comprises of optical filters built-in lenses and also surface areas These diodes have a slow response time when the surface area of

the photodiode increases Photodiodes are alike to regular semiconductor diodes

V-I Characteristics of Photodiode

V-I characteristics The voltage-current equation for photodiode is given by following equation P I = I (eV ηVT minus1) minus I0 (1)Here I0 reverse saturation current V applied potential to diode VT voltage equivalent to temperature=KTe ηconstant (=1 for Ge and 2 for Si) IP photo current The photocurrent is product of responsivity of photo diode and power of incident light ie IP=RλP The responsivity of a photodiode is a measure of the sensitivity to light and it is defined as the ratio of the photocurrent IP to the incident light power P at a given wavelength In the forward biased condition the current through diode increases exponentially But in thereverse biased diode V is negative hence the exponential term becomes less than 1 therefore hellipthe equation becomes as IR = minusI0 ndash IP

Using of photo Diode

Cameras Medical devices Safety equipment Optical communication devices Position sensors Bar code scanners Automotive devices Surveying instruments

12

Advantages of photodiode

1 can be used as variable resistance device2 Highly sensitive to the light3 The speed of the operation is very high the switching of current and hence

the resistance value from high to low or other wise is very fast

Disadvantages of photodiode(i) The dark current is temperature dependent (ii) The overall photo diode characteristics are temperature dependent Hence

have poor temperature stability(iii) The current and change in current is in the range of TA which may not be

sufficient to drive other circuits Hence amplification is necessary

6Pin diode

The PIN diode is a one type of photo detector used to convert optical signal into an electrical signal The PIN diode comprises of three regions namely P-region I-region and N-

region Typically both the P and N regions are heavily doped due to they are utilized for Ohmic contactsThe intrinsic region in the diode is in contrast to a PN junction diode This region makes the PIN diode an lower rectifier but it makes it appropriate for fast switches

attenuators photo detectors and applications of high voltage power electronics

IV-Characteristics of PIN DiodeThe forward series resistance characteristic and the reverse capacitance characteristic are shown graphically in Below Figure for a typical pin diode The pin diode is used as a dc-controlled microwave switch operated by rapid changes in bias or as a modulating device that takes advantage of the variable forward-resistance characteristic Since no recti1048619cation occurs at the pn junction a highfrequency signal can be modulated (varied) by a lower-frequency bias variation A pin diode can also be used in attenuator applications because its resistance can be controlled by the amount of

11

A photodiode is one type of light detector used to convert the light into current or voltage based on the mode of operation of the device

It comprises of optical filters built-in lenses and also surface areas These diodes have a slow response time when the surface area of

the photodiode increases Photodiodes are alike to regular semiconductor diodes

V-I Characteristics of Photodiode

V-I characteristics The voltage-current equation for photodiode is given by following equation P I = I (eV ηVT minus1) minus I0 (1)Here I0 reverse saturation current V applied potential to diode VT voltage equivalent to temperature=KTe ηconstant (=1 for Ge and 2 for Si) IP photo current The photocurrent is product of responsivity of photo diode and power of incident light ie IP=RλP The responsivity of a photodiode is a measure of the sensitivity to light and it is defined as the ratio of the photocurrent IP to the incident light power P at a given wavelength In the forward biased condition the current through diode increases exponentially But in thereverse biased diode V is negative hence the exponential term becomes less than 1 therefore hellipthe equation becomes as IR = minusI0 ndash IP

Using of photo Diode

Cameras Medical devices Safety equipment Optical communication devices Position sensors Bar code scanners Automotive devices Surveying instruments

12

Advantages of photodiode

1 can be used as variable resistance device2 Highly sensitive to the light3 The speed of the operation is very high the switching of current and hence

the resistance value from high to low or other wise is very fast

Disadvantages of photodiode(i) The dark current is temperature dependent (ii) The overall photo diode characteristics are temperature dependent Hence

have poor temperature stability(iii) The current and change in current is in the range of TA which may not be

sufficient to drive other circuits Hence amplification is necessary

6Pin diode

The PIN diode is a one type of photo detector used to convert optical signal into an electrical signal The PIN diode comprises of three regions namely P-region I-region and N-

region Typically both the P and N regions are heavily doped due to they are utilized for Ohmic contactsThe intrinsic region in the diode is in contrast to a PN junction diode This region makes the PIN diode an lower rectifier but it makes it appropriate for fast switches

attenuators photo detectors and applications of high voltage power electronics

IV-Characteristics of PIN DiodeThe forward series resistance characteristic and the reverse capacitance characteristic are shown graphically in Below Figure for a typical pin diode The pin diode is used as a dc-controlled microwave switch operated by rapid changes in bias or as a modulating device that takes advantage of the variable forward-resistance characteristic Since no recti1048619cation occurs at the pn junction a highfrequency signal can be modulated (varied) by a lower-frequency bias variation A pin diode can also be used in attenuator applications because its resistance can be controlled by the amount of

12

Advantages of photodiode

1 can be used as variable resistance device2 Highly sensitive to the light3 The speed of the operation is very high the switching of current and hence

the resistance value from high to low or other wise is very fast

Disadvantages of photodiode(i) The dark current is temperature dependent (ii) The overall photo diode characteristics are temperature dependent Hence

have poor temperature stability(iii) The current and change in current is in the range of TA which may not be

sufficient to drive other circuits Hence amplification is necessary

6Pin diode

The PIN diode is a one type of photo detector used to convert optical signal into an electrical signal The PIN diode comprises of three regions namely P-region I-region and N-

region Typically both the P and N regions are heavily doped due to they are utilized for Ohmic contactsThe intrinsic region in the diode is in contrast to a PN junction diode This region makes the PIN diode an lower rectifier but it makes it appropriate for fast switches

attenuators photo detectors and applications of high voltage power electronics

IV-Characteristics of PIN DiodeThe forward series resistance characteristic and the reverse capacitance characteristic are shown graphically in Below Figure for a typical pin diode The pin diode is used as a dc-controlled microwave switch operated by rapid changes in bias or as a modulating device that takes advantage of the variable forward-resistance characteristic Since no recti1048619cation occurs at the pn junction a highfrequency signal can be modulated (varied) by a lower-frequency bias variation A pin diode can also be used in attenuator applications because its resistance can be controlled by the amount of

13

current Certain types of pin diodes are used as photodetectors in fiber-optic systems

Advantages of PIN diode

High voltage rectfier The PIN diode can be used as a high voltage recti1048619er The intrinsic region provides a greater separationbetween the PN and N regions allowing higher reverse voltages to be tolerated

RF switchThe PIN diode makes an ideal RF switch The intrinsic layer between the P and N regions increases the distancebetween them This also decreases the capacitance between them thereby increasing he level of isolation when the diode isreverse biased

Photodetector As the conversion of light into current takes place within the depletion region of a photdiode increasing thedepletion region by adding the intrinsic layer improves the performance by increasing he volume in which light conversionoccurs

Disadvantages of PIN diodeHas a reverse recovery time which contributes to power loss

14

7Avalanche Diode

An avalanche diode is a special type of semiconductor device designed to operate in reverse breakdown region Avalanche diodes are used as relief valves (a type of valve used to control the pressure in a system) to protect electrical systems from excess voltages

How avalanche diode works

IV-Characteristics of Avalance Diode

In electronics an avalanche diode is a diode (made from silicon or other semiconductor) that is designed to experience avalanche breakdown at a specified reverse bias voltage

Current-voltage characteristics of electrical components and circuits can be collected in two ways

14

7Avalanche Diode

An avalanche diode is a special type of semiconductor device designed to operate in reverse breakdown region Avalanche diodes are used as relief valves (a type of valve used to control the pressure in a system) to protect electrical systems from excess voltages

How avalanche diode works

IV-Characteristics of Avalance Diode

In electronics an avalanche diode is a diode (made from silicon or other semiconductor) that is designed to experience avalanche breakdown at a specified reverse bias voltage

Current-voltage characteristics of electrical components and circuits can be collected in two ways

15

1 When potentiostatic access to connect to the electrode voltage Applied voltage

then gradually increase until it reaches the final voltage 2 In galvanostatic approach set stream which is then gradually increased to a final

current

Avalanche photodiode advantages and disadvantagesThe avalanche photodiode has a number of different characteristics to the normal p-n or p-i-n photodiodes making them more suitable for use in some applications In view of this it is worth summarising their advantages and disadvantages

The main advantages of the avalanche photodiode include

Greater level of sensitivity

The disadvantages of the avalanche photodiode include

Much higher operating voltage may be required

Avalanche photodiode produces a much higher level of noise than a p-n photodiode

Avalanche process means that the output is not linear

8Laser Diode

A laser diode also known as an injection laser or diode laser is a semiconductor device that produces coherent radiation (in which the waves are all at the same frequency and phase) in the visible or infrared (IR) spectrum when current passes through it Laser diodes are

16

used in optical fiber systems compact disc (CD) players laser printers remote-control devices and intrusion detection systems

IV-Characteristics of Laser Diode

The laser diode specification for the forward voltage across the diode is required in a number of areas of the design Often laser diode manufacturers prefer to place the voltage on the vertical axis

From the diagram it can be seen that the voltage across the laser diode is typically around 15 volts although it is necessary to check for the particular laser diode in question The forward voltage specification will vary according to the materials used in the diode current etc

Although the forward voltage does vary with temperature this is not normally a major consideration

Advantages of Diode LasersCompared to most laser types diode lasers are less expensive and more compact making them ideal for small electronic devices such as CD and DVD players CD-ROMs DVD-ROMs and other optical data storage devices Laser printers laser fax machines and supermarket bar code readers all use diode lasers Using helium-neon lasers increases the size of these devices by as much as five times Diode lasers use much less power than most types of lasers While gas and solid-state lasers require a power supply in kilo-volts diode lasers typically run on small volt batteries

Disadvantages of Diode LasersDiode laser beams are highly divergent meaning wedge-shaped instead of straight and parallel and have shorter coherent distances which makes for inferior quality in optics performance They are not as well-suited as helium-neon lasers for high-quality holography Moreover semiconductors in electronic devices are prone to static electrical discharges meaning diode lasers in these gadgets can be damaged by unstable and fluctuating power supply Also prone to gradual aging diode lasers over time use increasing amounts of power with diminishing efficiency

17

The lens required for beam correction adds to the diode lasers fragility such that damage to the lens renders the laser non-functional

9Light Emitting Diode (LED)

The holes are present in the valance band and the free electrons are in the conduction band When a p-n junction is forward biased the electron from n-type semiconductor material cross the p-n junction and combine with the holes in the p-type semiconductor material Thus with respect to the holes the free electrons are at higher energy level

IV-Characteristics of (LED)

18

For a Light Emitting Diode to emit any form of light it needs a current to flow through it as it is a current dependant device As the LED is to be connected in a forward bias condition across a power supply it should be current limited using a series resistor to protect it from excessive current flow From the graph above we can see that each LED has its own forward voltage drop across the PN-junction and this parameter which is determined by the semiconductor material used is the forward voltage drop for a given amount of forward conduction current

Advantage gt LEDs produce more light per watt than do incandescent bulbs this is useful in battery powered or energysaving devices

Disadvantage gt LED performance largely depends on the ambient temperature of the operating environment Driving the LED hard in high ambient temperatures may result in overheating of the LED package eventually leading to device failure

10P-N Junction Diode

A pndashn junction is a boundary or interface between two types of semiconductor material p-type and n-type inside a single crystal of semiconductor The p (positive) side contains an excess of holes while the n (negative) side contains an excess of electrons

18

For a Light Emitting Diode to emit any form of light it needs a current to flow through it as it is a current dependant device As the LED is to be connected in a forward bias condition across a power supply it should be current limited using a series resistor to protect it from excessive current flow From the graph above we can see that each LED has its own forward voltage drop across the PN-junction and this parameter which is determined by the semiconductor material used is the forward voltage drop for a given amount of forward conduction current

Advantage gt LEDs produce more light per watt than do incandescent bulbs this is useful in battery powered or energysaving devices

Disadvantage gt LED performance largely depends on the ambient temperature of the operating environment Driving the LED hard in high ambient temperatures may result in overheating of the LED package eventually leading to device failure

10P-N Junction Diode

A pndashn junction is a boundary or interface between two types of semiconductor material p-type and n-type inside a single crystal of semiconductor The p (positive) side contains an excess of holes while the n (negative) side contains an excess of electrons

19

Typically at room temperature the voltage across the depletion layer for silicon is about 06 ndash 07 volts and for germanium is about 03 ndash 035 volts This potential barrier will always exist even if the device is not connected to any external power source as seen in diodes

Advantage The world is going to be easy by using this diode day by day

P-n Junction I-V Characteristics

20

In Equilibrium the Total current balances due to the sum of the individual components

Submitted by

21

Robioul Hasan

BSC in EEE

City University of Bangladesh

FacebookcomRobioul999

Thank You

• A Diode is the simplest two-terminal unilateral semiconductor device It allows current to flow only in one direction and blocks the current that flows in the opposite direction The two terminals of the diode are called as anode and cathode The symbol of diode is as shown in the figure below
• Types of Diode The types of diode are as follow-
• • Characteristics
  • V-I characteristics of Schottky Diode
  • • 5Photodiode
    • 6Pin diode
    • The PIN diode is a one type of photo detector used to convert optical signal into an electrical signal The PIN diode comprises of three regions namely P-region I-region and N-region Typically both the P and N regions are heavily doped due to they are utilized for Ohmic contactsThe intrinsic region in the diode is in contrast to a PN junction diode This region makes the PIN diode an lower rectifier but it makes it appropriate for fast switches attenuators photo detectors and applications of high voltage power electronics
    • • 7Avalanche Diode
      • Avalanche photodiode advantages and disadvantages
      • • 8Laser Diode
        • IV-Characteristics of Laser Diode
        • • Advantages of Diode Lasers
          • Disadvantages of Diode Lasers
          • • 9Light Emitting Diode (LED)
            • IV-Characteristics of (LED)

20

In Equilibrium the Total current balances due to the sum of the individual components

Submitted by

21

Robioul Hasan

BSC in EEE

City University of Bangladesh

FacebookcomRobioul999

Thank You

• A Diode is the simplest two-terminal unilateral semiconductor device It allows current to flow only in one direction and blocks the current that flows in the opposite direction The two terminals of the diode are called as anode and cathode The symbol of diode is as shown in the figure below
• Types of Diode The types of diode are as follow-
• • Characteristics
  • V-I characteristics of Schottky Diode
  • • 5Photodiode
    • 6Pin diode
    • The PIN diode is a one type of photo detector used to convert optical signal into an electrical signal The PIN diode comprises of three regions namely P-region I-region and N-region Typically both the P and N regions are heavily doped due to they are utilized for Ohmic contactsThe intrinsic region in the diode is in contrast to a PN junction diode This region makes the PIN diode an lower rectifier but it makes it appropriate for fast switches attenuators photo detectors and applications of high voltage power electronics
    • • 7Avalanche Diode
      • Avalanche photodiode advantages and disadvantages
      • • 8Laser Diode
        • IV-Characteristics of Laser Diode
        • • Advantages of Diode Lasers
          • Disadvantages of Diode Lasers
          • • 9Light Emitting Diode (LED)
            • IV-Characteristics of (LED)

21

Robioul Hasan

BSC in EEE

City University of Bangladesh

FacebookcomRobioul999

Thank You

• A Diode is the simplest two-terminal unilateral semiconductor device It allows current to flow only in one direction and blocks the current that flows in the opposite direction The two terminals of the diode are called as anode and cathode The symbol of diode is as shown in the figure below
• Types of Diode The types of diode are as follow-
• • Characteristics
  • V-I characteristics of Schottky Diode
  • • 5Photodiode
    • 6Pin diode
    • The PIN diode is a one type of photo detector used to convert optical signal into an electrical signal The PIN diode comprises of three regions namely P-region I-region and N-region Typically both the P and N regions are heavily doped due to they are utilized for Ohmic contactsThe intrinsic region in the diode is in contrast to a PN junction diode This region makes the PIN diode an lower rectifier but it makes it appropriate for fast switches attenuators photo detectors and applications of high voltage power electronics
    • • 7Avalanche Diode
      • Avalanche photodiode advantages and disadvantages
      • • 8Laser Diode
        • IV-Characteristics of Laser Diode
        • • Advantages of Diode Lasers
          • Disadvantages of Diode Lasers
          • • 9Light Emitting Diode (LED)
            • IV-Characteristics of (LED)