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

Abstract

Deep-level transient spectroscopy (DLTS) was performed to investigate the energy levels introduced inside quantum wells in the active region of a quantum cascade laser (QCL) structure. To form a simple active region, we prepared samples with GaAs/AlGaAs three and single-quantum-well (QW) structures. At least two QW levels were observed from the DLTS spectra for a three-QW structure and their activation energies were calculated to be approximaely 0.11-0.13 eV for QW1 and 0.20-0.22 eV for QW2. The positions of energy levels in multi quantum wells were slightly shifted upward by the applied electric field. In the case of a single QW, an activation energy of 0.08eV was obtained.