A 4-GHz large-area (160000 μm/sup 2/) MSM-PD on ITG-GaAs

We report the first large-area (400 μm×400 μm) metal-semiconductor-metal photodetector (MSM-PD) with a FWHM of 86 ps (4-GHz bandwidth), and nanoamp dark currents at 10 V. This is achieved by using intermediate-temperature grown GaAs (ITG-GaAs) to tailor the carrier lifetime in the material, so that the lifetime/spl ap/transit time between the electrodes. This removes the slow tail response typical of the impulse response of MSM-PDs, without significantly reducing the responsivity. A comparison to normal-temperature GaAs is made demonstrating a dramatic improvement for large-area photodetectors. Thus, we have shown that ITG-GaAs is an excellent material for large-area detectors.