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24 October 2012 Fundamental interface studies of GaSb and InAs substrates with atomic layer deposition
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Long Wavelength infrared photodetectors based on Type-II superlattices from the 6.1Å system hold great promise for a wide variety of applications. However, as these materials are fabricated into focal plane arrays for real world applications, the small pixel sizes that are required can result in unacceptably high dark current due to a significant contribution of surface-induced leakage. These surface currents could be substantially reduced or even eliminated by the application of an appropriate passivation material. But, while a considerable amount of effort has gone into developing passivation processes and materials for these detectors (e.g. PECVD SiO2, polyimides, etc.), there is no one widely adopted standard technique in use today. Atomic layer deposition has the possibility of being an excellent method for depositing passivation because of the wide variety of materials that are readily available via ALD and the ability to conformally coat arbitrary topographies that may be found in the patterning of LWIR FPAs. In this work, fundamental materials characterization results and electrical test data will be presented for two wide band gap, high-K dielectrics (Titanium Oxide and Hafnium Oxide) looking at their nucleation and growth behavior on substrates of relevant III-V materials such as GaSb and InAs using ellispometry, XPS, and XRD. These results will be compared to more conventional passivation strategies to highlight the unique features of the ALD technique.
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Frank Greer, L. Baker, S. Cook, A. Fisher, S. Keo, A. Soibel, Arezou Khoshakhlagh, J. Nguyen, D. Ting, and S. Gunapala "Fundamental interface studies of GaSb and InAs substrates with atomic layer deposition", Proc. SPIE 8511, Infrared Remote Sensing and Instrumentation XX, 851108 (24 October 2012);

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