MSM-Metal Semiconductor Metal Photo-detector Using Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Detection

Report No. ARL-TR-6176
Authors: Fred Semendy, Patrick Taylor, Gregory Meissner, and Priyalal Wijewarnasuriya
Date/Pages: September 2012; 18 pages
Abstract: We have investigated for the first time the electrical properties of metal-semiconductor-metal (MSM) photodectors fabricated using black silicon-germanium on silicon substrate (Si1-xGex//Si) for I-V, optical response, external quantum efficiency (EQE), internal quantum efficiency (IQE), and responsivity and reflectivity. Silicon-germanium (Si1-xGex)/Si with variations of Ge were blackened by metal enhanced chemical etching (MECE) using nanometer-scale gold particles as catalyst and HF:H2O2:CH3COOH solution as etchant. The etched surface was black, textured, and showed strong suppression of reflectivity. These properties are consistent with Si1-xGex becoming highly micro-structured due to metal catalysis and wet etching. Using the blackened SiGe/Si, MSM photodiodes were fabricated and tested. The lowering of reflection using a U.S. Army Research Laboratory (ARL)-developed technique has helped the enhancement of absorption in Si1-xGex to provide increased optical response, which is an important milestone towards practical, extended wavelength (~2 μm) electro-optical applications.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2012