EFFECT OF ASYMMETRIC BARRIERS ON PERFORMANCES OF GAAS ALGAAS QUANTUM-WELL DETECTORS/

Recently, the efficient tuning of the carrier capture efficiency of qu antum well by introducing a barrier asymmetry was demonstrated [J. M. Gerard, Appl. Phys. Lett. 63, 240 (1993)]. The electron launching effe ct was proposed to improve the gain of multiquantum well detectors. In this article, we give experimental results on the dark current, noise , optical gain, responsivity, and detectivity of barrier asymmetric qu antum well detectors. We confirm that the electron launching reduces t he capture efficiency and thus improves the gain. In addition to this effect, the modification of the barrier potential profile induces a da rk current reduction and a blue shift of the intersubband transition. All these effects are then taken into account for analyzing detector p erformances. As a result of the comparison between symmetric and asymm etric detectors, we do not see any net advantage of using asymmetric s tructures for improving detector performances. (C) 1995 American Insti tute of Physics.