HIGH-RESPONSIVITY INGAAS MSM PHOTODETECTORS WITH SEMITRANSPARENT SCHOTTKY CONTACTS

High-performance metal-semiconductor-metal photodetectors (MSM-PD's) with interdigitated semi-transparent Au Schottky contacts have been fabricated on pseudomorphic In0.9Ga0.1P-InP-InGaAs heterostructure. 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 is decreased to 10 mn. This corresponds to a 75% improvement over the conventional MSM-PD's with opaque metal electrodes, With a pseudomorphic InGaP barrier-enhancement layer, these devices exhibit a dark current density as low as 1.6 pA/mu m(2). Extremely linear photoresponse without any internal gain is also observed for these detectors, The full-width at half maximum of the temporal response for the devices with semi-transparent electrodes is about 85 ps compared to 80 ps for the conventional ones.