We report the fabrication and characteristics of high-performance InGaAs MSM photodetectors with a 300-mu m x 300-mu m square and a 300-mu m-diameter circular detection area, With a pseudomorphic In0.9Ga0.1P cap layer, the detectors exhibit dark current densities less than 1 pA/mu m(2), The responsivity ranges between 0.4 and 0.6 A/W depending on finger spacing, Bandwidth over 1 GHz has been obtained for these large-area detectors, Our results also show that the circular detector exhibits better speed performance as compared to the square one due to its smaller parasitic RC constant.
