Electrical characterization of GaAs/AlGaAs multi-quantum wells for quantum cascade laser

In this study, we investigated the electrical properties of three QW active region by capacitance-voltage (C-V) and deep-level transient spectroscopy (DLTS) measurements (Blood, 1992 and Kim, 2004). Then, the optical properties were measured also by photoluminescence (PL) and Fourier transformed infra-red spectroscopy (FTIR), etc. In this study, we prepared GaAs/AlGaAs single and three QWs samples grown on n-GaAs substrates as a simplified active region except for other complex regions of QCL device. Generally, the QCL structure has made up of 26th∼40th period of the injection/active region, but the structure is too complicated to analyze electrical properties. Thus, we used simple structure in this study. And then, in order to measure C-V and DLTS, a Schottky diode was made by Au-gate formation and indium ohmic contact below the backside.