Intersubband semiconductor lasers (ISLs) are of great interest for mid-infrared (2-20 .mu.m) device applications. These semiconductor devices have a wide range of applications from pollution detection and industrial monitoring to military functions.ISLs have generally encountered several problems which include slow intrawell intersubband relaxation times due to the large momentum transfer and small wave-function overlap of the initial and final electron states in interwell transitions. Overall, the ISL's of the prior art are subject to weak intersubband population inversion.The semiconductor device of the present invention provides optimal intersubband population inversion by providing a double quantum well active region in the semiconductor device. This region allows for small momentum transfer in the intersubband electron-phonon resonance with the substantial wave-function overlap characteristic of the intersubband scattering.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional application of U.S. patent application Ser. No. 09/957,531 filed Sep. 21, 2001, now U.S. Pat. No. 6,819,696.
