Abstract

Heterojunction phototransistors (HPTs) are promising candidates as high gain IR detectors for fiber optic communications. Unlike avalanche photodiodes, HPTs can provide high optical gain without excess noise due to avalanching. In contrast with the HPTs grown by liquid phase epitaxy or metal-organic chemical vapor deposition, molecular beam epitaxially grown AlGaAs/ GaAs HPTs have yielded small optical gains.¹ We have demonstrated optical gains in excess of 500 A/W for an AlGaAs/ GaAs HPT with an InGaAs region in the collector. In addition we introduced an InGaAs strained layer in the collector, which in turn enables us to study experimentally the influence of the absorption location on the current gain.

© 1990 Optical Society of America