Low shot noise GaAs/AlGaAs heterojunction phototransistors grown by MBE with a delta-doped base

Novel GaAs/AlGaAs heterojunction phototransistors with a delta -doped base have been fabricated. Very high gain and low output noise have been measure d. The measured noise is composed ofshol noise associated with collector qu iescent bias current and amplifed shot noise due to collector leaf; current for non-passivated devices. For well-passivated devices, the measured nois e is, as predicted previously [Y. Wang, E.S. Yang, J. Appl. Phys. 74 (1993) 6978], just composed of the shot noise associated with collector quiescent bias current. The high gain and low intrinsic noise characteristics of the se transistors make them very promising in weak light dt tection. (C) 2001 Elsevier Science B.V. All rights reserved.