Gain and Bandwidth in Semiconductor Photodetectors

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Gain and Bandwidth in Semiconductor Photodetectors. S W McKnight and C A DiMarzio. length=l. Area=A. Photoconductivity. Φ p = photon flux (photon/sec). η = quantum efficiency. Photoconductor Responsivity. Photoconductor Detectivity and Bandwidth. Sample thickness ~ absorption length - PowerPoint PPT Presentation

Transcript of Gain and Bandwidth in Semiconductor Photodetectors

  • Gain and Bandwidth in Semiconductor PhotodetectorsS W McKnight and C A DiMarzio

  • Photoconductivityp = photon flux (photon/sec) = quantum efficiency

  • Photoconductor Responsivity

  • Photoconductor Detectivity and BandwidthSample thickness ~ absorption lengthPhotoconductive Gain ~ nBandwidth ~ 1/ nGain/Bandwidth product ~ constant

  • Photovoltaic DetectionEfEx+-Depletion RegionEvEcJdiffusionJdriftJunction built-in voltageVo

  • Photovoltaic Detection: Gain and BandwidthTransit across depletion region fast (vdrift)Diffusion to depletion region slow (vdiff <
  • Diffusion and Drift VelocityJdiff = q Dn dn/dx = n q vdiffvdiff = Dn 1/n dn/dx = Dn d/dx [ln(n)] ~ Dn ln(gop ) / (1/) < < vthermal = sqrt (kT/m)vdrift = n

  • Carrier Conductivity MassConductivity mass:

  • Silicon Conductivity Massxyzaabbc

  • Silicon Conductivity Mass

  • Thermal vs. Drift Velocity

  • Carrier Saturation VelocitiesElectronsHoles

  • Photovoltaic Sensing CircuitVph+-

  • Photoconductive Sensing CircuitVd+-Iph

  • Photoconductive DetectionEfEx+-Depletion RegionEvEcJdriftVo+ Vd

  • Depletion Region Width

  • Absorption Length for Semiconductor

    Chart2

    0.00576417260.0073046272

    0.00567341710.0078576565

    0.00560911290.0080543811

    0.00557572640.0066507553

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    0.00543643210.0065411532

    0.00543609130.0065178463

    0.00558962880.0064813804

    0.00566436770.0064304877

    0.00560725770.0063867379

    0.00547751140.0063041746

    0.00529767330.0062587606

    0.00509344780.0061593095

    0.00484080080.0061092371

    0.00455807780.0060071757

    0.00433135810.0059340516

    0.00421529730.0058088166

    0.00418155990.0057183186

    0.00438067820.0055638256

    0.00503362120.0054452425

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    2.07373010840.0197671642

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    3.00159936380.0389160848

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    3.25769512350.0456384305

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    3.89236722360.0592507552

    4.09943591760.062805871

    4.19311081080.0661792117

    4.2237174590.0704089192

    4.72702678590.073974552

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    5.10018056810.0816001534

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    6.49881164590.1058894632

    6.69172627730.1108076164

    6.97471501970.1154646462

    7.19071856560.120489642

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    7.8543814220.1300492396

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    9.12798274390.1498164201

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    10.3711380230.170133843

    10.6103047280.1777329255

    11.04477841290.1836935426

    11.51028593260.1899461083

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    13.39821642940.2100770531

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    38.53215927520.5593146349

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    43.53345616320.620210596

    46.50297619050.6548440491

    49.86843222140.6776311923

    53.71466768530.7016213022

    58.1526316820.7269888102

    63.3302563450.7537373238

    63.66182836770.7820625512

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    77.18996689580.9095640004

    86.20872591460.9717476972

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    97.97953272221.0760673696

    112.54501800721.1118715163

    131.96566505391.2062683588

    132.62880909941.2343765644

    159.95034377391.2061801835

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    859.43468296411240

    863.41354723711305

    10901378

    10951459

    11001550

    1653

    1771

    1907

    Silicon

    GaAs

    Wavelength (nm)

    Absorption Length (microns)

    Absorption Length vs. Wavelength

    Sheet1

    1.7814,3600.69653.7790.1520.152

    1.7614,2000.70453.7720.1340.134

    1.7414,0300.71263.7620.1270.127

    1.7213,8700.72083.7520.1180.118

    1.713,7100.72933.7420.1120.112

    1.6813,5500.7383.7340.1050.105

    1.6613,3900.74693.7250.1010.101

    1.6413,2300.7563.7160.0970.097

    1.6213,0700.76533.7070.0930.093

    1.612,9000.77493.70.0910.091

    1.5812,7400.78473.6930.0890.089

    1.5612.580.79483.6850.0870.087

    1.5412,4200.80513.6790.0850.085

    1.5212,2600.81573.6720.0830.083

    1.512,1000.82663.6660.080.08

    1.4912,0000.83210.07287.28

    1.4811,9400.83770.06866.86

    1.4711,8600.84340.06646.64

    1.4611,7800.84920.06286.28

    1.4511,6900.85510.06126.12

    1.4411,6100.8610.05685.68

    1.43511,5700.8640.05575.57

    1.4311,5300.8670.05725.72

    1.42511,4900.870.05545.54

    1.4211,4500.87310.02712.71

    1.4111,3700.87930.005955.95

    1.411,2900.88563.6140.001691.69

    1.3911,2100.8920.0005685.68

    1.3811,1300.89840.000252.5

    1.3711,0500.9050.0001331.33

    1.3510,8900.91843.569

    1.310,4900.95373.5388

    1.2510,0800.99193.5138

    1.29,6791.0333.492

    1.159,2751.0783.4724

    1.18,8721.1273.4546

    1.058,4691.1813.4383

    18,0651.243.4232

    0.957,6621.3053.4094

    0.97,2591.3783.3965

    0.856,8561.4593.3847

    0.86,4521.553.3737

    0.756,0491.6533.3636

    0.75,6461.7713.3543

    0.655,2431.9073.3457

    Sheet2

    0.45584.7410.739

    0.45924.6940.696

    0.46264.6490.659

    0.46614.6050.626

    0.46964.5670.595

    0.47324.5250.569

    0.47694.4920.539

    0.48064.4560.517

    0.48434.4230.497

    0.48814.3920.476

    0.4924.3620.458

    0.49594.3330.441

    0.49994.3050.426

    0.5044.2790.411

    0.50814.2540.398

    0.51234.2290.385

    0.51664.2050.371

    0.52094.1830.359

    0.52544.1620.347

    0.52994.1410.337

    0.53444.120.327

    0.53914.10.32

    0.54384.0820.308

    0.54864.0630.301

    0.55354.0450.294

    0.55854.0290.285

    0.56364.030.276

    0.56873.9980.266

    0.5743.9830.257

    0.57943.9680.251

    0.58483.9540.245

    0.59043.940.24

    0.59613.9270.232

    0.60193.9140.228

    0.60783.9020.223

    0.61383.890.213

    0.61993.8780.211

    0.62623.8670.203

    0.63263.8560.196

    0.63913.8460.187

    0.64583.8360.183

    0.65263.8260.179

    0.65953.8170.173

    0.66663.8090.173

    0.67383.7990.168

    0.68123.7920.158

    0.68883.7850.151

    2.72

    Sheet3

    0.32293.5121.905

    0.32633.5011.909

    0.33153.4881.92

    0.33513.4851.931

    0.34063.4891.95

    0.34443.4951.965

    0.35023.5131.992

    0.35423.5312.013

    0.35633.5412.024

    0.35833.5532.036

    0.36043.5662.049

    0.36253.582.062

    0.36473.5962.076

    0.36683.6142.091

    0.3693.6352.107

    0.37123.6572.123