High-speed InGaAs metal-semiconductor-metal photodetectors with improved responsivity and process yield

High-performance In0.9Ga0.1P-InP-InGaAs metal-semiconductor-metal photodectors with semi-transparent Au Schottky contacts are fabricated and studied. The devices, with an active area of 50×50 μm2 and different finger spacings of 2, 3 and 4 μm, all exhibit high responsivities over 0.7 AW-1 and low dark currents below 10 nA. Extremely linear photoresponse without low frequency internal gain is also observed in these devices. The novel fabrication process used in this work is simple and has nearly 100% high yield. A device with a small finger spacing has also been demonstrated to have improved speed performance without sacrificing its responsivity.