Novel metal-semiconductor-metal photodetectors (MSM-PDs) with interdigitated semi-transparent Au Schottky contacts have been fabricated on pseudomorphic In0.9Ga0.1P/InP/InGaAs heterostructure grown by low-pressure MOCVD. The responsivity. measured at 1.55 mu m wavelength is greatly enhanced from 0.4 A/W to 0.7 A/W as the thickness of the Au electrodes are decreased to 10 nm. These devices have an extremely linear photoresponse and show no internal gain. The devices with an active region of 100 mu m x 100 mu m, a finger width of 3 mu m, and a finger spacing of 3 mu m exhibit dark currents as low as 16 nA at 10 V. The full-width at half maximum of the temporal response for the device with semi-transparent electrodes is about 85 ps compared to 80 ps for the conventional device with opaque electrodes.