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

Recently, the efficient tuning of the carrier capture efficiency of quantum well by introducing a barrier asymmetry was demonstrated [J. M. Gerard, Appl. Phys. Lett. 63, 240 (1993)]. The electron launching effect 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 quantum well detectors. We confirm that the electron launching reduces the capture efficiency and thus improves the gain. In addition to this effect, the modification of the barrier potential profile induces a dark current reduction and a blue shift of the intersubband transition. All these effects are then taken into account for analyzing detector performances. As a result of the comparison between symmetric and asymmetric detectors, we do not see any net advantage of using asymmetric structures for improving detector performances. (C) 1995 American Institute of Physics.