Doping-induced type-II to type-I transition and interband optical gain in InAs/AlSb quantum wells

We show that proper doping of the barrier regions can convert the well-known type-II InAs/AlSb quantum wells (QWs) to type I, producing strong interband transitions comparable to regular type-I QWs. The interband gain for TM mode is as high as 4000 1/cm, thus providing an important alternative material system in the midinfrared wavelength range. We also study the TE and TM gain as functions of doping level and intrinsic electron–hole density.