High Efficiency, High Speed GaAs Thin Film Inversed MSM Photodetectors

Summary form only given. MSM photodetectors are amactive for integration with receiver circuits since they have lower capacitance than p-i-n detectors with the same surface area. Low external q u a " efficiency (2O"to 40%), however, is a disadvantage of MSMs, which is primarily due to fmger electrode shadowing. Several research teams had investigated novel ways to enhance the quantum efficiency such as transparent indium tin oxide kctrcdes (ITO-MSM) [I], and a Brag mirror on the bot" to defme a Fabry-Perot cavity [21. The IT0 MSMs demonstrated much higher quantum efficiency, but speed degradation was also noted due to the high resistivity IT0 contacts. The B r a mirror design produced only a moderate increase in efficiency. In this paper, invened MSMs (1-MSMs), with metallized fmgen on the bonom of the MSMs, are reported at 850 nm in GaAdAIGaAs. with record extemal quantum efficiency for normal incidence MSMs at this speed.