Absorption coefficient of intersubband transition at 1.55 µm in (CdS/ZnSe)/BeTe quantum wells

In this paper, the intersubband optical absorption coefficient is calculated in a ZnSe/CdS/ZnSe quantum well (QW) surrounded by BeTe barriers. First, the one-dimensional Poisson and Schr?dinger equations have been solved self-consistently, and then the intersubband optical absorption between the lowest two levels has been theoretically studied under an external electric field. Simulated results including eigenvalues, absorption coefficient and electroabsorption properties have been discussed. The structure under investigation covers a large range of the electromagnetic spectra including the visible and near infrared (IR). For the 1.55??m wavelength (0.8?eV), dependences of the intersubband optical absorption coefficient on the applied electric field, thickness of the barrier and concentration of doping are investigated. Our calculation shows that for an applied electric field lower than a critical value of around 100?kV?cm?1, the ITSB optical absorption peak undergoes a red shift with the increase in the electric field. However, for an applied electric field above the critical value, the electrons move to the same side of the well for all states. The energy difference E2 ? E1 increases leading to a blue shift of the absorption peak. As a result, the optical intersubband transition enhances its intensity. Taking into account the present results, we hope that important IR photodetectors and near-IR laser amplifiers can be constructed based on the group II?VI QWs.