A 4-GHz large-area (160 000 μm2) MSM-PD on ITG-GaAs

We report the first large-area (400 mu m x 400 mu m) 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 approximate to transit time between the electrodes, This removes the slow tail response typical of the impulse response of MSM-PD's, 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.