High performance In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As metal-semiconductor-metal photodetectors

Performance data are presented for OMCVD (organometallic chemical vapor deposition) grown In/sub 0.52/Al/sub 0.48/As-In/sub 0.53/Ga/sub 0.47/As planar Schottky barrier metal-semiconductor-metal (M-S-M) photodetectors. The high-quality In/sub 0.52/Al/sub 0.48/As and In/sub 0.52/Al/sub 0.48/As-In/sub 0.53/Ga/sub 0.47/As heterointerface resulted in devices with record low leakage current densities of approximately 1 mA/cm/sup 2/ electrode metal, a fast pulse response without a long tail portion, and a low 1/f/sup a/-like noise component at low frequencies. The fully depleted detector had a responsitivity of 0.4 A/W at 1.31 mu m, corresponding to unity internal quantum efficiency, and a pulse response of 49 ps FWHM (full width at half maximum) was recorded for an incident 27-ps pulse of 1.3- mu m light, in close agreement with predictions of a transit time analysis. This model was then used to analyze the dependence of the pulse response on the device dimensions and to examine the tradeoff between bandwidth and efficiency in the generic InGaAs M-S-M detector. Finally, the detector noise was examined. A low level of 1/f/sup a/-like noise was found at low frequencies, with shot noise behavior at higher frequencies, increasing above this close to breakdown. Illumination was found to depress the 1/f/sup a/ low-frequency noise component. Under normal biasing conditions, shot noise behavior would persist down to kilohertz frequencies.<>