At&t Bell Laboratories

Ock-Ky Kim

Stephen R Forrest

Richard G Smith

In.sub.0.53 Ga.sub.0.47 As p-i-n photodiodes with room temperature dark currents as low as 0.1 nA at -10 V bias are realized by introducing a wide bandgap (e.g., quaternary InGaAsP) cap layer on the ternary InGaAs.

Back-illuminated photodiode with a wide bandgap cap layer

An avalanche photodetector useful at wavelengths as long as 1.7 microns with low noise is achieved. The crystal used includes successive layers of p-type indium phosphide, n-type indium phosphide, and n-type indium gallium arsenide. An appropriate total of fixed charges in the n-type indium phosphide and a graded bandgap heterointerface region are important for the improved results.

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Bridgewater, NJ, United States of America

Ock-Ky Kim