HIGH-SPEED INGAAS METAL-SEMICONDUCTOR-METAL PHOTODETECTORS WITH THIN ABSORPTION LAYERS

The responsivity and the bandwidth of metal-semiconductor-metal photod etectors (MSMPD's) with different InGaAs absorption layer thicknesses and electrode geometries were investigated, By decreasing the InGaAs t hickness from 1.0 to 0.25 mu m, the bandwidth was found to increase by approximately a factor of 2, while the responsivity was found to decr ease by almost a factor of 3 from 0.29 to 0.10 A/W at a bias of -5 V. Devices with an electrode width and spacing of 1 mu m and a 0.25-mu m absorption layer displayed a bandwidth of 19.5 GHz when biased at -15 V under front-side illumination with 1.55-mu m light.