High-speed performance of OMCVD grown InAlAs/InGaAs MSM photodetectors at 1.5 mu m and 1.3 mu m wavelengths

A report is presented on the fabrication of high-speed In/sub 0.53/Ga/sub 0.47/As metal-semiconductor-metal (MSM) photodetectors incorporating a high-quality lattice-matched InAlAs barrier enhancement layer, grown by organometallic chemical vapor deposition (OMCVD). Fast responses of approximately 55 ps full-width half-maximum at 1.5 mu m and approximately 48 ps at 1.3 mu m wavelengths are observed, corresponding to intrinsic device bandwidths of approximately 8 GHz and approximately 11 GHz, respectively. The absence of any tail to the pulse response, and of any low-bias DC gain, indicates a low-trap density at the InAlAs/InGaAs heterointerface. Bias independent dark currents of 10-20 mu A are observed below breakdown, which occurred at >30 V in devices with a 500-A-thick InAlAs layer.<>