EXTERNAL QUANTUM EFFICENECY OFA CADMIUM TELLURIDE

CADMIUM SULFIDE PHOTOVOLTAIC CELL

by

Amy Ferguson

Submitted to the Department of Physics in partial fulfillment of graduation

requirements for the degree of

Bachelor of Science

Brigham Young University – Idaho

December 2010

Thesis Advisor: David Oliphant Committee Member: Richard Hatt

Signature: __________________ Signature: ____________________

Committee Member: R. Todd Lines

Signature: __________________

ii

Abstract

Finding the external quantum efficiency of a Cadmium Telluride – Cadmium

Sulfide photovoltaic cell is determined by knowing the current that the light produces and

the intensity of the light that is used. This process is to determine if the p-n junction of

the cadmium telluride – cadmium sulfide produces better efficiency than what has been

found before from different types of photovoltaic cells. The project has not been

completed due to problems that have not yet to be solved. The efficiencies found are not

accurate but the set-up is an idea to determine the external quantum efficiency.

iii

Acknowledgements

I would like to thank the Society of Physics Students for funding my internship at

the National Institute of Standards and Technology (NIST). Thanks go out to NIST and

my advisor Dr. Nhan V. Nguyen for helping me with my research and the data that is

included in this paper. I would finally like to thank Brigham Young University – Idaho

Physics Department for all the opportunities I have had while at school and for providing

me with my advisor David Oliphant who has helped me a ton.

iv

Table of Contents

1. BACKGROUND ........................................................................................................................ 1

1.1 Introduction ..................................................................................................................... 1

1.2 Physics of Semiconductors ............................................................................................. 1

1.3 Alternative Energy .......................................................................................................... 3

2. EXPERIMENT ........................................................................................................................... 5

2.1 How to solve for EQE ...................................................................................................... 5

2.2 Structure of Photovoltaic Cell .......................................................................................... 6

2.3 Set-up of Experiment ....................................................................................................... 7

3. OBSERVATIONS & RESULTS ................................................................................................ 8

4. CONCLUSION ......................................................................................................................... 11

References ..................................................................................................................................... 13

Appendix ....................................................................................................................................... 14

v

LIST OF FIGURES

1: Represents Band Gap .......................................................................................... 2

2: CdS-CdTe Photovoltaic cell provided by the University of Toledo, Right is the

side view enhanced to see the layers. Left, is the view from the top. ..................... 6

3: Set-up of lab equipment ...................................................................................... 8

4: Graph of the EQE% as a function of wavelength ............................................. 11

LIST OF TABLES

1: Measured Intensity Data ................................................................................... 14

2: EQE Data .......................................................................................................... 21

1

1. BACKGROUND

1.1 Introduction

A solar cell uses the photovoltaic effect to convert the light from the sun into

electrical energy. If solar cells were created to have higher efficiency, then they would be

very useful in the world today that is trying to find other ways to produce energy. The

photovoltaic effect is described simply as the conversion of light energy into electrical

energy. This was first discovered by Edmund Becquerel in 1839 when he observed an

electrical current being created when light acted on a silver coated platinum electrode in

an electrolyte solution [1]. So this idea has been around for almost two hundred years.

The most common solar cells today are silicon solar cells. This is because a solar cell is

essentially a semiconductor and most semiconductors are made with silicon. In 1954 the

first successful silicon solar cell was made by Chapin, Fuller, and Pearson [1]. The

efficiency of this solar cell was 4% [2]. This came about because of the development in

the silicon semiconductor.

1.2 Physics of Semiconductors

A semiconductor material is not a conductor and not an insulator, it has the

properties of both which makes it unique. A conductor allows the flow of electrons freely

without added energy. An insulator is a material that would allow the flow of electrons

but the band gap shown in figure 1 is a lot higher for an insulator so more energy is

required to move the electrons from the valence band to the conduction band. The energy

required for an insulator is too great to allow the flow of electrons. A semiconductor is a

material that has a band gap that requires a lower amount of energy to move the

electrons. A semiconductor is not just any type of material. It is determined by the lattice

2

structure of the atoms that make up the semiconductor material. The lattice structure is

like the structure of a crystal [3]. This gives it the properties for the unique flow of

electrons. The use of semiconductors in electronic devices like the television, radio and,

computers have “revolutionized our way of life” [4]. A semiconductor material either

wants more electrons or wants to get rid of electrons which is why a p-n junction can

form.

A p-n junction is essential to the structure of the solar cell; it is why the solar cell

produces electricity. The p-n junction is caused by a p-type semiconductor being in

contact with a n-type semiconductor. The n-type means negative which says there is an

excess of electrons, it wants to get rid of its electrons. The p-type is the positive side

which lacks electrons; it wants to get more electrons. The electrons flow forward bias

from the n side to the p side. Energy needs to be given to the electrons for them to flow.

The potential energy difference between the valence band of electrons of the p side and

the conduction band of the n side is how much energy is required to create a current. This

gap is shown in the Figure 1 below.

Figure 1: Represents Band Gap

This difference is referred to as the band gap. The band gap is different for every material

and that is why there is a difference in the types of photovoltaic cells. The smaller the

3

band gap the less energy is required to move the electrons. The more electrons that move

from the conduction band to the valence band the more current that is produced. In a

photovoltaic the energy given to the electrons is from light, solar energy. The energy

from the sun is free compared to many other sources of energy. If a solar cell can become

efficient to produce a large current at little cost, for example around 1 cent per kilowatt

hour, then they would be economically valuable.

1.3 Alternative Energy

Solar Cells are made from different materials which include, monocrystalline

silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium

selenide [5]. The solar cell that was used in this project was created at the University of

Toledo and it is a Cadmium Sulfide (CdS) Cadmium Telluride (CdTe) solar cell. V. G.

Karpov, Diana Shvydka, and Yann Roussillon, from the University of Toledo, wrote a

paper titled Physics of CdTe Photovoltaics: from Front to Back, explaining the structure

of their photovoltaic cell that is similar to the one I used. They expressed their views on

using a CdTe photovoltaic as a practical way of improving photovoltaics. Karpov claims

that the unique structure of CdTe creates the possibility for a better photovoltaic. Their

results are due to their observations for the need for a good back contact, the band gap

between CdS and CdTe is small, and the crystalline structure of CdTe produces an

effective photovoltaic [6].

Recently, there has been a big push in alternative energy. The conventional ways

of producing energy are coal, oil, natural gas, nuclear, and hydroelectric. The United

States relies heavily on coal to produce 22% of the total energy consumption [7]. “A

large electric plant consumes more than 20,000 tons of coal per day. Each ton generates

4

about 2,000 kilowatt hours of electricity, enough to power the average home for a third of

a year” [7]. 20,000 tons of coal is a lot and that is being burned to produce energy. A

concern is that eventually the coal will run out. “Approximately 58 billion tons of coal

have been produced in the United States since the first commercial mine was established

more than 200 years ago” [7]. So a look for alternative energy is a big concern in politics

and science.

Alternative energy is focused on using non conventional sources. It includes

renewable energy which is when the source replenishes themselves (unlike the

conventional ways that once the coal or oil is burned it can’t come back.) Renewable

energy sources include the sun, ocean waves and tides, wind, and rivers. Also, there is a

big push for “green” energy which means that the energy is clean, low or nonpolluting

energy [7]. In all reality every form of energy has some kind of pollution. In the case of

coal when burned carbon dioxide is produced. This is hazardous to human health. Carbon

dioxide is also produced from the burn of oil and gas, like in a car. There is technology to

limit the emission of carbon dioxide but is too expensive for personal use. The

technology is used to have clean coal produced a coal production plants [7]. The world is

going “green” and if energy production goes “green” the debates about which energy is

best can cease.

A renewable and “green” energy source is the sun and so a solar cell can be a

solution to the problem of finding better and more efficient alternative energy. The

development of the photovoltaic is the way to use solar energy and convert it to

electricity. The problem is that the efficiency of the photovoltaic cell is not high enough

to make them useful. A problem with using the light of the sun is that it isn’t concentrated

5

on to just one spot, it is spread out and doesn’t always hit the cell orthogonally. If the sun

light was able to be focused and hitting the cell at an angle of 90 degrees the efficiency

would increase and the surface area of the cell and cost would decrease by a factor of

1000 [7]. The development of the CdTe photovoltaic is improving the efficiency and one

step closer to finding the solution.

2. EXPERIMENT

2.1 How to solve for EQE

The purpose of the experiment is to find the external quantum efficiency (EQE) of

the CdTe photovoltaic. The EQE can be determined by dividing the number of electrons

by the number of photons, shown in Eq. (1).

����%� =����� �

�ℎ�� � × 100 �1�

This is under the assumption that for every photon of light it should produce one electron

through the solar cell. The number of photons is determined by measuring the volts and

converting it to amps using the gain which is the ratio of voltage and amps. From amps

convert it to watts which are joules per second and so we divide the energy of one photon

in joules to get the number of photons as shown in the steps of Eq. (2) below. The energy

of a photon is dependent to its wavelength so the equation will be a function of

wavelength.

The number of electrons per secon

coulombs (C) per second and dividing it by the charge of one electron

below. The current is a function of wavelength and so the number of electrons will also

be a function of wavelength.

����� �

�

2.2 Structure of Photovoltaic Cell

As seen in Figure 2 the different layers of the photovoltaic have different thicknesses.

The glass layer is approximately 1

and its thickness is 0.1-0.3 µm. HRT is an unknown substance

the picture being drawn close to scale it is about the same thickness as CdS. CdS as stated

Figure 2: CdS-CdTe Photovoltaic cell provided by the University of Toledo

enhanced to see the layers. Left, is the view from the top.

6

� = ��

� =���

�

�ℎ�� ����

�= ���� ×

1�

The number of electrons per second is found by measuring the current (I) which is in

per second and dividing it by the charge of one electron as shown in Eq

The current is a function of wavelength and so the number of electrons will also

be a function of wavelength. The charge of one electron is 1.602 x 10-19

C

����� ���� � ���� � 11.602 x 10 " 19 C

2 Structure of Photovoltaic Cell

the different layers of the photovoltaic have different thicknesses.

The glass layer is approximately 1-3 mm. TCO stands for a transparent conductive oxide

0.3 µm. HRT is an unknown substance to me and my advisor,

eing drawn close to scale it is about the same thickness as CdS. CdS as stated

CdTe Photovoltaic cell provided by the University of Toledo, Right is the side view

enhanced to see the layers. Left, is the view from the top.

(2)

(I) which is in

as shown in Eq. (3)

The current is a function of wavelength and so the number of electrons will also

C.

�3�

the different layers of the photovoltaic have different thicknesses.

3 mm. TCO stands for a transparent conductive oxide

to me and my advisor, by

eing drawn close to scale it is about the same thickness as CdS. CdS as stated

, Right is the side view

7

above is Cadmium Sulfide and it is a n-type of the semiconductor and has a thickness of

0.08-0.3 µm. The Cadmium Telluride (CdTe) layer is a p-type side of the semiconductor

and is 1.5-7 µm thick. The back contact is doped with copper (Cu). The dark region in the

top view of Figure 2 is the ground. The ovals represent areas that can produce current. To

measure the current an electrometer is used and one tip is connected to the dark gray

region and then other is connected to where the light is shined on which is in the center of

one of the ovals.

2.3 Set-up of Experiment

Below is Figure 3 which is the actual set-up of the experiment. First is a 300W

lamp that is in place to act like the sun. Next the light is sent through a monochromator

that splits the light and makes it only one wavelength anywhere in the spectrum from 1

eV to 4eV. When it comes out of the monochromator it is sent through a chopper that

gives the light a certain frequency. The chopper frequency is set to something different

than the frequency of light that comes from the light bulbs in the room. The chopper

frequency is set to a lock-in amplifier that makes the detector ignore all other frequencies

of light. When the light comes out of the chopper it is reflected off a mirror to collimate

the light, then it is reflected off another mirror through a lens focusing the light to a point

which is shining on a spot of the solar cell or the detector.

8

When the detector is present it measures the voltage created from the light. The detector

is a NIST-calibrated Silicon detector. The voltage is read into a privately made computer

program written by Dr. Nhan V. Nguyen, NIST semiconductor electronics division. The

data is in table format and saved into a text file. The file is then taken and opened up into

a table represented by Table 1 in the Appendix. Table 1’s data is the intensity of the light

measured in volts at different wavelengths measured in electron-Volts. Using that data

the number of photons per second as a function of photon energy can be determined.

3. OBSERVATIONS & RESULTS

The experiment is run using the computer program that Dr. Nguyen wrote. The

program reads in the current for every different photon energy. The different photon

energy is created by the program changing the wavelength of light coming out of the

Figure 3: Set-up of lab equipment

lamp

monochomator

Detector or Solar Cell

9

monochromator. The photon energy was measured in electron-Volts (eV), before starting

the program the increment change of the photon energy represented by ∆eV was set as

seen in Table 1 of the appendix. ∆eV was set to .01eV and for Table 2 of the appendix

∆eV was set to .02eV. First, the experiment is run with the detector in the set-up to

measure the intensity in volts. Then, the detector is replaced with the photovoltaic and the

current is measured. The program uses the intensity and current data to compute the EQE

in percentage. The data is compared with each other in Table 2 in the Appendix. Figure 4

below is the graph representation of that data.

Test 1 is a run that was done by Dr. Nguyen before I got to NIST it was the first

test to see the EQE was being calculated correctly by predicting the shape of the graph

and the result is what was expected. The values are not accurate because it says at the

highest point the efficiency will get above 350%. This would mean that we are producing

more energy than we are giving into the system. That concept would be ideal but in

reality that will never occur. Thinking more about the optics of the light coming into the

solar cell we determined that the intensity of light we found that is used to determine the

number of photons per second was calculated incorrectly because the intensity would

change when the light hits the top layer of glass of the solar cell. The difference in the

index of refraction between the air and the glass makes it so not all the light is transmitted

through the glass, some is reflected off. So we needed to calculate the intensity of the

light that was transmitted. I determined the transmitted intensity by the equations 4, 5,

and 6 below. I in equation 4 represents the intensity of light, Iincident is what was measured

from the detector and that data is in Table 1 in the appendix. In equation 5 n1 represents

the index of refraction of air and n2 in equation 5 is determined by equation 6. Equation 6

10

is the index of refraction for fused silicon. Dr. Nguyen adjusted the computer program for

the newly calculated intensity.

� = �1 − &��'(�')*(+. �4�

& � -(. /01 234 (5674 89.95 1:; 23 <5(. /01 23= (5674 89.95 1:; 23 <5>

�+ -(.674 89.95 1:; 23 <54 (5 /01 23

(.674 89.95 1:; 23 <5= (5 /01 23>

� (5)

�� " 1 =.69616663��

�� − 0.068403�+

0.4079426��

�� − 0.1162414�+

0.8974794��

�� − 9.896161� �6�

Full Run 1 was done after the corrections were put into the program. The EQE

was expected to rise because the intensity would be lower which would make the number

of photons per second less having the denominator in Eq. 1 be less which causes a bigger

EQE. Our predictions were correct and the EQE jumped up and the data says that there is

over 1000% efficiency at some points. This is not correct. The problem was that in the

program the conversion was off by a factor of 100 which made the intensity appear

smaller than it was. This was fixed in the program for full run 2. Full Run 2 was then run

and the data collected. The data was still higher than what we expect. The max EQE for

Full Run 2 was recorded as 43.73% at 1.7eV. Previously the highest recorded efficiency

measured was to be 24.2% [2]. We were expecting to see an efficiency around 15% and

we were 3 times greater than that.

11

Figure 4: Graph of the EQE% as a function of photon energy

4. CONCLUSION

Our experiment produced results that were not close to what we had predicted.

The EQE was greater than expected. There is not conclusive evidence that the CdS-CdTe

photovoltaic is more efficient than previous photovoltaics cells. There is more work that

needs to be done on the experiment. The process of how we collect the data needs to be

improved. Also, knowing if all the light that the detector measured is focused on the

photovoltaic when measuring the current needs to be looked into more. The detector is

bigger and so it detects more light than the solar cell and this is a problem. There is future

research still being done by Dr. Nguyen at NIST. Dr. Nguyen is working on modifying

the setup to measure 3 D structures of CdTe thin film photovoltaic and triple junction. At

this point there is no conclusion if this type of photovoltaic is better or worse.

0.00E+00

2.00E+02

4.00E+02

6.00E+02

8.00E+02

1.00E+03

1.20E+03

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

EQ

E %

Photon Energy (eV)

CdS-CdTe EQE%

Test 1

Full Run 1

Full Run 2

12

Photovoltaic cells can be used to set up residential photovoltaic systems, which

would mean a house would run on solar energy. This would be a big market once they are

made for residential use. They can also be used to power commercial properties like,

office buildings, stores, hospitals, and schools. The transportation industry could also use

the cells to power cars, boats, and recreational equipment. Photovoltaic cells will be able

to power anything that runs on electricity. There are so many things that can be done with

the use of solar energy similar to that which is listed above. The cost for solar energy is

relatively low a photovoltaic is just more than 2 cents per kilowatt hour compared to 5

cents per kilowatt hour which is the cost for coal. With the lower cost more electronics

are going to move to being powered by solar energy. Imagine an iPod that doesn’t have

to be recharged by plugging in the cord to an outlet of the compute but that the back of it

is a photovoltaic and all that needs to be done is for it to be out in the sun. This is the

possibility of a photovoltaic cell. The applications are endless.

13

References

[1] Nelson, Jenny. The Physics of Solar Cells. (Imperial College Press, London, UK,

2003).

[2] SunPower Sets Solar Cell Efficiency Record at 24.2%.

http://www.renewableenergyworld.com/rea/news/article/2010/06/sunpower-sets-

solar-cell-efficiency-record-at-24-2

[3] Zeghbroeck, B. Van. Principles of Semiconductors. (2007)

http://ecee.colorado.edu/~bart/book/book/

[4] Stokes, Harold T. Solid State Physics, . (Brigham Young University, Provo, UT,

2007), p. 113-134.

[5] Jacobson, Mark Z. Review of Solutions to Global Warming, Air Pollution, and

Energy Security.

(http://www.rsc.org/Publishing/Journals/EE/article.asp?doi=b809990c, 2008).

[6] Karpov, V. G.; Shvydka, Diana; Roussillon. Physics of CdTe Photovoltaics: from

Front to Back. Invited talk f10.1 MRS Spring Meeting 2005, March28 – April 1,

San Francisco, CA.

[7] Berinstein, Paula. Alternative Energy. (Oryx Press, Westport, CT, 2001).

14

Appendix

Table 1: Measured Intensity Data

SR830 Sensitivity : 1 V/uA;

FERTO Preamp: 1.200000

wavelength

(eV) wavelength (nm) Intensity (volts)

1 1239.852 0.0044

1.01 1227.576 0.0045

1.02 1215.541 0.0045

1.03 1203.74 0.0045

1.04 1192.165 0.0047

1.05 1180.811 0.0049

1.06 1169.672 0.0057

1.07 1158.74 0.0061

1.08 1148.011 0.007

1.09 1137.479 0.0084

1.1 1127.138 0.0109

1.11 1116.984 0.0171

1.12 1107.011 0.022

1.13 1097.214 0.0202

1.14 1087.59 0.0309

1.15 1078.132 0.0356

1.16 1068.838 0.0355

1.17 1059.703 0.0452

1.18 1050.722 0.0701

1.19 1041.892 0.0651

1.2 1033.21 0.0806

1.21 1024.671 0.0963

1.22 1016.272 0.1658

1.23 1008.01 0.1708

1.24 999.881 0.2008

1.25 991.882 0.6967

1.26 984.01 0.2549

1.27 976.261 0.3755

1.28 968.634 0.2526

1.29 961.126 0.1951

1.3 953.732 0.3193

1.31 946.452 0.3645

1.32 939.282 0.3933

1.33 932.22 0.226

1.34 925.263 0.2502

1.35 918.409 0.6398

1.36 911.656 0.2778

1.37 905.001 0.685

1.38 898.444 0.3873

1.39 891.98 0.3324

1.4 885.609 0.5961

1.41 879.328 0.4787

1.42 873.135 0.1913

1.43 867.029 0.1382

1.44 861.008 0.1098

1.45 855.07 0.1004

1.46 849.214 0.1017

1.47 843.437 0.1643

1.48 837.738 0.2286

1.49 832.115 0.273

1.5 826.568 0.5991

1.51 821.094 0.3821

1.52 815.692 0.1515

1.53 810.361 0.1342

1.54 805.099 0.1292

1.55 799.905 0.1401

1.56 794.777 0.1361

1.57 789.715 0.1551

1.58 784.716 0.1298

1.59 779.781 0.1336

1.6 774.908 0.1403

1.61 770.094 0.1564

1.62 765.341 0.2751

1.63 760.645 0.1818

1.64 756.007 0.1747

1.65 751.425 0.1883

1.66 746.899 0.1936

1.67 742.426 0.2063

1.68 738.007 0.2109

1.69 733.64 0.2322

1.7 729.325 0.2197

1.71 725.06 0.2129

1.72 720.844 0.2205

1.73 716.677 0.2379

1.74 712.559 0.2448

15

1.75 708.487 0.2385

1.76 704.461 0.2417

1.77 700.481 0.2502

1.78 696.546 0.2558

1.79 692.655 0.2771

1.8 688.807 0.2874

1.81 685.001 0.3023

1.82 681.237 0.2864

1.83 677.515 0.2788

1.84 673.833 0.2741

1.85 670.19 0.2616

1.86 666.587 0.251

1.87 663.022 0.2347

1.88 659.496 0.2245

1.89 656.006 0.2306

1.9 652.554 0.2407

1.91 649.137 0.2436

1.92 645.756 0.2455

1.93 642.41 0.2496

1.94 639.099 0.254

1.95 635.822 0.2574

1.96 632.578 0.2645

1.97 629.367 0.268

1.98 626.188 0.2662

1.99 623.041 0.2735

2 619.926 0.2814

2.01 616.842 0.2815

2.02 613.788 0.284

2.03 610.765 0.2866

2.04 607.771 0.2866

2.05 604.806 0.2896

2.06 601.87 0.2867

2.07 598.962 0.2891

2.08 596.083 0.2991

2.09 593.231 0.3057

2.1 590.406 0.3083

2.11 587.608 0.3116

2.12 584.836 0.3165

2.13 582.09 0.3076

2.14 579.37 0.3163

2.15 576.675 0.3205

2.16 574.006 0.3233

2.17 571.36 0.3246

2.18 568.739 0.3181

2.19 566.142 0.3268

2.2 563.569 0.325

2.21 561.019 0.3248

2.22 558.492 0.3336

2.23 555.987 0.3384

2.24 553.505 0.3328

2.25 551.045 0.3395

2.26 548.607 0.3405

2.27 546.19 0.3375

2.28 543.795 0.3408

2.29 541.42 0.3417

2.3 539.066 0.3393

2.31 536.732 0.3468

2.32 534.419 0.3487

2.33 532.125 0.3503

2.34 529.851 0.3482

2.35 527.597 0.3532

2.36 525.361 0.3561

2.37 523.144 0.3573

2.38 520.946 0.3598

2.39 518.767 0.3582

2.4 516.605 0.3636

2.41 514.461 0.366

2.42 512.336 0.3573

2.43 510.227 0.3572

2.44 508.136 0.362

2.45 506.062 0.3684

2.46 504.005 0.3671

2.47 501.964 0.3678

2.48 499.94 0.3681

2.49 497.933 0.3767

2.5 495.941 0.3923

2.51 493.965 0.4123

2.52 492.005 0.41

2.53 490.06 0.3904

2.54 488.131 0.3844

2.55 486.216 0.3941

2.56 484.317 0.4172

16

2.57 482.433 0.4261

2.58 480.563 0.4062

2.59 478.707 0.3931

2.6 476.866 0.3928

2.61 475.039 0.4332

2.62 473.226 0.4645

2.63 471.427 0.4586

2.64 469.641 0.4823

2.65 467.869 0.4788

2.66 466.11 0.4374

2.67 464.364 0.4223

2.68 462.631 0.407

2.69 460.912 0.3942

2.7 459.204 0.3876

2.71 457.51 0.3801

2.72 455.828 0.3693

2.73 454.158 0.3681

2.74 452.501 0.3789

2.75 450.855 0.3879

2.76 449.222 0.3642

2.77 447.6 0.3408

2.78 445.99 0.3298

2.79 444.391 0.3289

2.8 442.804 0.3297

2.81 441.228 0.3318

2.82 439.664 0.3316

2.83 438.11 0.3326

2.84 436.568 0.3205

2.85 435.036 0.3195

2.86 433.515 0.318

2.87 432.004 0.3168

2.88 430.504 0.3122

2.89 429.015 0.3053

2.9 427.535 0.3099

2.91 426.066 0.3095

2.92 424.607 0.3036

2.93 423.158 0.3036

2.94 421.718 0.3037

2.95 420.289 0.3039

2.96 418.869 0.3014

2.97 417.459 0.2907

2.98 416.058 0.2908

2.99 414.666 0.2913

3 413.284 0.2904

3.01 411.911 0.2829

3.02 410.547 0.2777

3.03 409.192 0.2785

3.04 407.846 0.2711

3.05 406.509 0.2726

3.06 405.18 0.2685

3.07 403.861 0.2706

3.08 402.549 0.2697

3.09 401.247 0.2683

3.1 399.952 0.2659

3.11 398.666 0.2622

3.12 397.388 0.2621

3.13 396.119 0.2573

3.14 394.857 0.2514

3.15 393.604 0.2446

3.16 392.358 0.2406

3.17 391.121 0.2365

3.18 389.891 0.2325

3.19 388.668 0.228

3.2 387.454 0.2189

3.21 386.247 0.2145

3.22 385.047 0.2151

3.23 383.855 0.2124

3.24 382.67 0.208

3.25 381.493 0.2039

3.26 380.323 0.2004

3.27 379.16 0.1928

3.28 378.004 0.1886

3.29 376.855 0.1865

3.3 375.713 0.1835

3.31 374.578 0.1828

3.32 373.449 0.1796

3.33 372.328 0.176

3.34 371.213 0.1732

3.35 370.105 0.1679

3.36 369.004 0.1677

3.37 367.909 0.1638

3.38 366.82 0.1645

17

3.39 365.738 0.1632

3.4 364.662 0.1599

3.41 363.593 0.1565

3.42 362.53 0.1563

3.43 361.473 0.1554

3.44 360.422 0.1544

3.45 359.377 0.148

3.46 358.339 0.1485

3.47 357.306 0.1461

3.48 356.279 0.1462

3.49 355.258 0.1457

3.5 354.243 0.1439

3.51 353.234 0.1405

3.52 352.231 0.1404

3.53 351.233 0.139

3.54 350.241 0.1367

3.55 349.254 0.1342

3.56 348.273 0.1326

3.57 347.297 0.1297

3.58 346.327 0.128

3.59 345.363 0.1246

3.6 344.403 0.1199

3.61 343.449 0.1192

3.62 342.501 0.1188

3.63 341.557 0.1163

3.64 340.619 0.1117

3.65 339.685 0.1103

3.66 338.757 0.1083

3.67 337.834 0.1057

3.68 336.916 0.1042

3.69 336.003 0.1009

3.7 335.095 0.1002

3.71 334.192 0.098

3.72 333.294 0.0964

3.73 332.4 0.0943

3.74 331.511 0.0908

3.75 330.627 0.0876

3.76 329.748 0.0869

3.77 328.873 0.0847

3.78 328.003 0.0827

3.79 327.138 0.081

3.8 326.277 0.0786

3.81 325.42 0.0764

3.82 324.569 0.0744

3.83 323.721 0.072

3.84 322.878 0.0702

3.85 322.039 0.0681

3.86 321.205 0.0659

3.87 320.375 0.0624

3.88 319.549 0.0598

3.89 318.728 0.0589

3.9 317.911 0.0574

3.91 317.098 0.0557

3.92 316.289 0.0543

3.93 315.484 0.0523

3.94 314.683 0.0503

3.95 313.887 0.0485

3.96 313.094 0.0468

3.97 312.305 0.0456

3.98 311.521 0.0438

3.99 310.74 0.0411

4 309.963 0.0403

4.01 309.19 0.0379

4.02 308.421 0.0368

4.03 307.656 0.0356

4.04 306.894 0.0337

4.05 306.136 0.0322

4.06 305.382 0.0311

4.07 304.632 0.0292

4.08 303.885 0.0283

4.09 303.142 0.027

4.1 302.403 0.0252

4.11 301.667 0.0241

4.12 300.935 0.0227

4.13 300.206 0.0212

4.14 299.481 0.0201

4.15 298.76 0.0191

4.16 298.041 0.0177

4.17 297.327 0.0162

4.18 296.615 0.0154

4.19 295.907 0.0143

4.2 295.203 0.0132

18

4.21 294.502 0.0124

4.22 293.804 0.0115

4.23 293.109 0.0105

4.24 292.418 0.0095

4.25 291.73 0.0088

4.26 291.045 0.008

4.27 290.363 0.0074

4.28 289.685 0.0065

4.29 289.01 0.0059

4.3 288.338 0.0054

4.31 287.669 0.005

4.32 287.003 0.0045

4.33 286.34 0.0041

4.34 285.68 0.0037

4.35 285.023 0.0034

4.36 284.37 0.0031

4.37 283.719 0.0029

4.38 283.071 0.0026

4.39 282.426 0.0024

4.4 281.785 0.0022

4.41 281.146 0.002

4.42 280.51 0.0019

4.43 279.876 0.0018

4.44 279.246 0.0016

4.45 278.618 0.0015

4.46 277.994 0.0014

4.47 277.372 0.0013

4.48 276.753 0.0013

4.49 276.136 0.0012

4.5 275.523 0.0012

4.51 274.912 0.0012

4.52 274.304 0.0011

4.53 273.698 0.001

4.54 273.095 0.001

4.55 272.495 0.001

4.56 271.897 0.001

4.57 271.302 0.0009

4.58 270.71 0.0009

4.59 270.12 0.0009

4.6 269.533 0.0009

4.61 268.948 0.0009

4.62 268.366 0.0009

4.63 267.787 0.0009

4.64 267.209 0.0009

4.65 266.635 0.0009

4.66 266.063 0.0009

4.67 265.493 0.0009

4.68 264.926 0.0009

4.69 264.361 0.0009

4.7 263.798 0.0009

4.71 263.238 0.0008

4.72 262.681 0.0008

4.73 262.125 0.0008

4.74 261.572 0.0008

4.75 261.021 0.0008

4.76 260.473 0.0008

4.77 259.927 0.0008

4.78 259.383 0.0008

4.79 258.842 0.0008

4.8 258.303 0.0008

4.81 257.765 0.0008

4.82 257.231 0.0008

4.83 256.698 0.0008

4.84 256.168 0.0008

4.85 255.64 0.0008

4.86 255.114 0.0008

4.87 254.59 0.0008

4.88 254.068 0.0008

4.89 253.548 0.0008

4.9 253.031 0.0008

4.91 252.516 0.0008

4.92 252.002 0.0008

4.93 251.491 0.0008

4.94 250.982 0.0008

4.95 250.475 0.0008

4.96 249.97 0.0008

4.97 249.467 0.0008

4.98 248.966 0.0008

4.99 248.467 0.0008

5 247.97 0.0008

5.01 247.475 0.0008

5.02 246.982 0.0008

19

5.03 246.491 0.0008

5.04 246.002 0.0008

5.05 245.515 0.0008

5.06 245.03 0.0008

5.07 244.547 0.0008

5.08 244.065 0.0008

5.09 243.586 0.0008

5.1 243.108 0.0008

5.11 242.632 0.0008

5.12 242.159 0.0008

5.13 241.687 0.0008

5.14 241.216 0.0008

5.15 240.748 0.0008

5.16 240.281 0.0008

5.17 239.817 0.0008

5.18 239.354 0.0008

5.19 238.892 0.0008

5.2 238.433 0.0008

5.21 237.975 0.0008

5.22 237.52 0.0008

5.23 237.065 0.0008

5.24 236.613 0.0008

5.25 236.162 0.0008

5.26 235.713 0.0008

5.27 235.266 0.0008

5.28 234.82 0.0008

5.29 234.377 0.0008

5.3 233.934 0.0008

5.31 233.494 0.0008

5.32 233.055 0.0008

5.33 232.618 0.0008

5.34 232.182 0.0008

5.35 231.748 0.0008

5.36 231.316 0.0008

5.37 230.885 0.0008

5.38 230.456 0.0008

5.39 230.028 0.0009

5.4 229.602 0.0009

5.41 229.178 0.0009

5.42 228.755 0.0009

5.43 228.334 0.0009

5.44 227.914 0.0009

5.45 227.496 0.0009

5.46 227.079 0.0009

5.47 226.664 0.0009

5.48 226.25 0.0009

5.49 225.838 0.0009

5.5 225.428 0.0009

5.51 225.019 0.0009

5.52 224.611 0.001

5.53 224.205 0.001

5.54 223.8 0.001

5.55 223.397 0.001

5.56 222.995 0.001

5.57 222.595 0.001

5.58 222.196 0.001

5.59 221.798 0.001

5.6 221.402 0.001

5.61 221.007 0.001

5.62 220.614 0.001

5.63 220.222 0.0011

5.64 219.832 0.001

5.65 219.443 0.001

5.66 219.055 0.001

5.67 218.669 0.001

5.68 218.284 0.001

5.69 217.9 0.001

5.7 217.518 0.001

5.71 217.137 0.001

5.72 216.757 0.001

5.73 216.379 0.001

5.74 216.002 0.001

5.75 215.626 0.001

5.76 215.252 0.001

5.77 214.879 0.0011

5.78 214.507 0.0011

5.79 214.137 0.0011

5.8 213.768 0.0012

5.81 213.4 0.0012

5.82 213.033 0.0012

5.83 212.668 0.0012

5.84 212.303 0.0012

20

5.85 211.941 0.0012

5.86 211.579 0.0012

5.87 211.218 0.0012

5.88 210.859 0.0011

5.89 210.501 0.0011

5.9 210.144 0.0011

5.91 209.789 0.0011

5.92 209.434 0.0011

5.93 209.081 0.0011

5.94 208.729 0.0011

5.95 208.378 0.0011

5.96 208.029 0.0011

5.97 207.68 0.0012

5.98 207.333 0.0012

5.99 206.987 0.0012

6 206.642 0.0012

21

Table 2: EQE Data

eV Test 1 Full Run 1 Full Run 2

1.2 4.65E+00 31.93 1.22E+00

1.22 1.05E+00 8.37 3.02E-01

1.24 4.02E-01 3.51 1.33E-01

1.26 1.72E-01 1.62 5.22E-02

1.28 1.49E+00 12.77 4.79E-01

1.3 5.61E-01 4.69 1.78E-01

1.32 1.10E+00 8.97 3.30E-01

1.34 3.20E-01 2.78 1.03E-01

1.36 3.09E-01 2.59 1.09E-01

1.38 5.52E-01 4.59 1.56E-01

1.4 8.13E-01 6.79 2.13E-01

1.42 3.19E+00 22.67 8.58E-01

1.44 1.18E+01 79.19 3.05E+00

1.46 5.58E+01 352.70 1.51E+01

1.48 1.14E+02 705.74 2.59E+01

1.5 1.29E+02 838.58 2.49E+01

1.52 1.65E+02 962.03 3.70E+01

1.54 1.73E+02 973.60 3.84E+01

1.56 1.80E+02 977.82 3.69E+01

1.58 1.87E+02 991.03 3.79E+01

1.6 1.95E+02 997.60 4.05E+01

1.62 1.99E+02 1009.70 3.96E+01

1.64 2.05E+02 1020.90 3.94E+01

1.66 2.12E+02 1037.20 4.12E+01

1.68 2.20E+02 1041.60 4.07E+01

1.7 2.24E+02 1057.10 4.15E+01

1.72 2.39E+02 1072.70 4.37E+01

1.74 2.37E+02 1054.50 4.05E+01

1.76 2.43E+02 1071.50 4.21E+01

1.78 2.59E+02 1096.50 4.44E+01

1.8 2.54E+02 1068.90 4.18E+01

1.82 2.66E+02 1076.50 4.29E+01

1.84 2.71E+02 1075.50 4.29E+01

1.86 2.75E+02 1064.10 4.21E+01

1.88 2.77E+02 1059.40 4.29E+01

1.9 2.79E+02 1057.70 4.17E+01

1.92 2.89E+02 1062.80 4.24E+01

1.94 2.96E+02 1073.90 4.24E+01

1.96 2.99E+02 1050.10 4.28E+01

1.98 3.05E+02 1066.70 4.24E+01

2 3.17E+02 1055.50 4.24E+01

2.02 3.20E+02 1064.70 4.27E+01

2.04 3.23E+02 1064.40 4.30E+01

2.06 3.32E+02 1069.70 4.36E+01

2.08 3.37E+02 1072.60 4.38E+01

2.1 3.37E+02 1070.60 4.30E+01

2.12 3.48E+02 1071.80 4.33E+01

2.14 3.56E+02 1065.30 4.35E+01

2.16 3.60E+02 1055.90 4.31E+01

2.18 3.62E+02 1047.10 4.27E+01

2.2 3.65E+02 1022.30 4.22E+01

2.22 3.58E+02 1011.60 4.09E+01

2.24 3.65E+02 983.26 4.09E+01

2.26 3.58E+02 963.31 4.01E+01

2.28 3.56E+02 942.91 3.88E+01

2.3 3.58E+02 903.35 3.77E+01

2.32 3.50E+02 891.76 3.67E+01

2.34 3.41E+02 855.46 3.57E+01

2.36 3.39E+02 839.62 3.51E+01

2.38 3.41E+02 815.21 3.41E+01

2.4 3.36E+02 782.78 3.32E+01

2.42 3.21E+02 756.09 3.19E+01

2.44 3.15E+02 714.81 3.00E+01

2.46 3.12E+02 677.85 2.84E+01

2.48 2.99E+02 642.57 2.74E+01

2.5 2.89E+02 611.27 2.58E+01

2.52 2.78E+02 587.95 2.51E+01

2.54 2.79E+02 575.98 2.39E+01

2.56 2.78E+02 564.25 2.37E+01

2.58 2.76E+02 556.92 2.40E+01

2.6 2.82E+02 546.12 2.39E+01

2.62 2.70E+02 526.02 2.16E+01

2.64 2.81E+02 520.98 2.20E+01

2.66 2.79E+02 511.89 2.18E+01

2.68 2.74E+02 497.39 2.10E+01

2.7 2.76E+02 488.49 2.13E+01

2.72 2.69E+02 478.73 1.99E+01

2.74 2.73E+02 471.62 2.04E+01

2.76 2.72E+02 460.95 1.99E+01

2.78 2.75E+02 453.80 1.97E+01

22

2.8 2.73E+02 446.61 1.93E+01

2.82 2.73E+02 437.09 1.90E+01

2.84 2.75E+02 431.83 1.87E+01

2.86 2.78E+02 425.77 1.86E+01

2.88 2.72E+02 419.69 1.84E+01

2.9 2.78E+02 413.59 1.80E+01

2.92 2.73E+02 406.39 1.79E+01

2.94 2.75E+02 399.86 1.77E+01

2.96 2.74E+02 394.82 1.74E+01

2.98 2.74E+02 388.11 1.71E+01

3 2.74E+02 380.72 1.67E+01

3.02 2.75E+02 372.24 1.65E+01

3.04 2.79E+02 364.92 1.66E+01

3.06 2.79E+02 358.26 1.62E+01

3.08 2.75E+02 351.82 1.55E+01

3.1 2.74E+02 343.92 1.54E+01

3.12 2.73E+02 335.67 1.50E+01

3.14 2.73E+02 328.09 1.48E+01

3.16 2.74E+02 321.62 1.45E+01

3.18 2.74E+02 313.59 1.41E+01

3.2 2.74E+02 306.35 1.38E+01

3.22 2.75E+02 300.56 1.36E+01

3.24 2.78E+02 297.21 1.34E+01

3.26 2.81E+02 294.00 1.33E+01

3.28 2.84E+02 286.43 1.29E+01

3.3 2.83E+02 278.58 1.26E+01

3.32 2.74E+02 269.56 1.21E+01

3.34 2.70E+02 258.90 1.17E+01

3.36 2.63E+02 248.29 1.13E+01

3.38 2.58E+02 238.39 1.08E+01

3.4 2.47E+02 228.31 1.03E+01

3.42 2.40E+02 219.28 9.94E+00

3.44 2.27E+02 211.23 9.57E+00

3.46 2.22E+02 202.39 9.13E+00

3.48 2.10E+02 193.06 8.81E+00

3.5 1.98E+02 182.01 8.33E+00

3.52 1.87E+02 172.73 7.91E+00

3.54 1.73E+02 160.05 7.35E+00

3.56 1.62E+02 148.48 6.87E+00

3.58 1.51E+02 135.75 6.23E+00

3.6 1.36E+02 122.81 5.69E+00

3.62 1.21E+02 109.62 5.01E+00

3.64 1.09E+02 95.87 4.42E+00

3.66 9.15E+01 81.10 3.73E+00

3.68 7.85E+01 68.68 3.17E+00

3.7 6.42E+01 56.91 2.61E+00

3.72 5.25E+01 45.46 2.09E+00

3.74 4.08E+01 35.44 1.63E+00

3.76 3.14E+01 27.28 1.25E+00

3.78 2.41E+01 20.94 9.65E-01

3.8 1.83E+01 15.69 7.26E-01

3.82 1.38E+01 11.75 5.40E-01

3.84 1.05E+01 8.88 4.18E-01

3.86 8.26E+00 6.98 3.32E-01

3.88 6.96E+00 5.88 2.79E-01

3.9 6.31E+00 5.34 2.53E-01

3.92 6.12E+00 5.16 2.45E-01

3.94 6.16E+00 5.15 2.49E-01

3.96 6.34E+00 5.37 2.55E-01

3.98 6.73E+00 5.64 2.73E-01

4 7.25E+00 6.04 2.92E-01