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26 September 2007 Dark current reduction of GaInAsSb based photodetectors by surface treatment with octadecylthiol
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In this work, we report dark current reduction, which is achieved by surface treatment with Octadecylthiol (OTD), for GaInAsSb based photodetectors. Epitaxial layers of the GaInAsSb photodetector were grown on n-type GaSb substrates with a horizontal MOCVD reactor, and the devices were fabricated by wet chemical etching. Surface treatment was carried out by immersing fresh-prepared detector samples in molten ODT solution maintained at 100 °C for 5 hours. The ODT treated devices show an order of magnitude reduction in the leakage current density in comparison with the untreated devices. The inverse of the dynamic zero bias resistance area product (1/R0A) is also lower for ODT treated devices. XPS analyses indicate the formation of Ga-S (20.1 eV) and In-S (445.3 eV) bonds at the surface and reduction in the formation of native oxide on ODT treated GaInAsSb surface. This means that surface treatment with ODT can effectively passivate dangling bonds and also reduce the native oxide. These results indicate that ODT can be used for an effective passivation technique when more sophisticated processing steps are further developed.
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Y. G. Xiao, V. Bhagwat, I. Bhat, and P. Dutta "Dark current reduction of GaInAsSb based photodetectors by surface treatment with octadecylthiol", Proc. SPIE 6660, Infrared Systems and Photoelectronic Technology II, 66600V (26 September 2007);

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