Investigation of optoelectronic properties of amorphous silicon germanium photodetectors

Cost consideration of the development of electronic devices is one of prime importance. One simple approach to lower the cost of production of photovoltaic and detectors is by using low cost materials such as amorphous silicon and germanium. These two semiconductors have different optoelectronic properties, such as energy gap, photoconductivity and absorption coefficient. The use of an alloy from the mixing of silicon with certain percentages of germanium would produce photodetectors with improved electronic characteristics and photoconductivity. A number of a-SiGe alloy thin films with different quantities of germanium have been fabricated using thermal vacuum evaporation technique. Conduction mechanism and activation energy of the prepared samples had been calculated and analyzed. The I-V characteristics, the photogenerated current and detectivity of these samples are subjected to measurement and discussion. Hall measurements are also conducted so to calculate the Hall I-V characteristics, Hall mobility, carrier concentration and type identification of the samples.