LOW DARK CURRENT AND HIGH-SPEED METAL-SEMICONDUCTOR-METAL PHOTODETECTOR ON SULFUR-TREATED INP

Abstract

We report on a metal-semiconductor-metal (MSM) photodetector on sulfur-treated undoped InP. We show that the dark current and capacitance of the sulfur-treated detector are 100 times lower and 30% smaller than those of the untreated detector, respectively. The improved performance of the detector characteristics is understood in terms of Fermi level depinning and the existence of a thin layer of InPxSy between the contact metal and semiconductor due to sulfur treatment. We found that it is necessary to anneal the sulfur-treated substrates at 270 degrees C to obtain such improved device characteristics. The reason is attributed- to the formation of thermally stable In-S bonds.