11 June 2013 Epitaxially passivated mesa-isolated InGaAs photodetectors
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We have fabricated low-dark-current InGaAs photodetectors utilizing an epitaxial structure incorporating an InAlGaAs passivation layer and a simple mesa isolation process, and requiring no implant or diffusion steps. At 295 K, areal and perimeter dark current contributions are 15 nA/cm2 and 9 pA/cm, respectively, in devices with large aspect ratios biased at -0.1 V. High responsivity was achieved even at zero bias in these devices. Devices were modeled using a commercial drift-diffusion simulator. Good fits to reverse dark current-voltage measurements were obtained using a model that included both bulk and interfacial generation mechanisms. Assuming similar electron and hole Shockley-Read-Hall lifetimes, dark current under small reverse bias are consistent with generation at the interface between the absorber and underlying layers. With increasing negative bias a large increase in dark current is associated with depletion near the InAlGaAs/absorber interface, while small increases in current at large reverse bias suggest long Shockley-Read-Hall lifetimes in the absorber. Forward biasing of these devices results in efficient injection of minority carrier holes into the absorber region, mimicking photogeneration and providing a method to predict the performance of illuminated detector arrays.
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John F. Klem, John F. Klem, Jin K. Kim, Jin K. Kim, Michael J. Cich, Michael J. Cich, Samuel D. Hawkins, Samuel D. Hawkins, Darin Leonhardt, Darin Leonhardt, Torben R. Fortune, Torben R. Fortune, Wesley T. Coon, Wesley T. Coon, } "Epitaxially passivated mesa-isolated InGaAs photodetectors", Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 870402 (11 June 2013); doi: 10.1117/12.2016558; https://doi.org/10.1117/12.2016558

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