Frequency response mechanisms for the GaAs MSM photodetector and electron detector

The GaAs metal-semiconductor-metal (MSM) device is a very useful planar and monolithic-microwave integrated-circuit compatible photodetector and elect ron-detector. As a photodetector, the MSM has been used for many applicatio ns in the past, however, in this paper we demonstrate its usefulness as an electron-beam detector as well. We present here a comprehensive analysis of the primary detection mechanism (electric field enhanced collection of gen erated electrons) as well as a newly identified secondary mechanism. This n ew mechanism is characterized by a high detection gain, but low speed. Expe rimental results are presented to verify the analysis, and possible applica tions are suggested by utilizing each one of the two detection mechanisms.