electron band structure in solids

formation of bands

Sodium

Silicon

semiconductor conductivity vs. T and doping

valence and conduction band structure

ndoping:electronsaremajority

carriers

nodoping

pdoping:Holesaremajority

carriers

Fermi‐Dirac

func9on

densityof

states

Fermi‐Dirac

func9on

densityof

statesX

structure of a p-n junction

applying an external potential to the p-n junction

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p-n junction diode

E

NP

I=Io[exp(eV/kBT)‐1]

junction diode I-V curve

photodiode

‐ +

current(A)/op>calpower(W)=A/W=λ(nm)xQE}/1240

QE=1

photodiode response

current=e[ne]=e[QE(np)]=e[QE(op>calpower/{hc/λ})]

Vout(V)={op>calpower(W)xλ(nm)xQExRf(Ω)}/1240

photodiode and current amplifier

Vout(V)=A/WxRf(Ω)

light emitting diode (LED)

lock-in amplifier

Robert H. Dicke

the triode

V+

load line (slope = R = 50KΩ)

R 50KΩ

L. De Forest (1907)

bipolar transistor (BJT)

J.Bardeen,W,Shockley,W.BraSainBellLabs(1948)NobelPrize(1956)

field effect transistor (FET)

USpatent1,745,175(1925)

USpatent2,502,488(1948)

USpatent2,013,564(1931)electroly>ccapacitor

bipolar junction transistor (BJT)

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+

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+

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bipolar junction transistor (BJT) – how it works

E B C ‐ +

‐ +

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+ ‐

‐ +

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p-n junction diode

E

NP

I=Io[exp(eV/kBT)‐1]

junction diode I-V curve

single stage common emitter circuit

p-n-p transistor

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+

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complementary transistors – control + and - voltage

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+

junction field effect transistor (JFET)

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+

circuit biasing n-channel JFET and circuit symbols

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