Optical properties of the GaAs/AlGaAs Step-like QWW for THz Applications

In this study, we calculated the linear and nonlinear optical properties of step-like AlGaAs/GaAs quantum well wires operating in THz band width. The time-independent Schrödinger equation was solved under the effective mass approximation using the finite element method. The wavefunctions and energy levels corresponding to the first four bounded states were obtained for the step-like quantum well wires. The potential barrier heights were set as 160 meV and 228 meV to create step-like potential. In the paper, firstly, the effect of the bottom width of the wire (Lin), from 8 nm to 12 nm, was considered. It was seen that bottom width of the wire defined where the localization happened in the step-like quantum well wire. The transition energies, occurs in the THz range, of the (1–2), (1–3), (2–4), and (3–4) were constant under applied electric field in the range of 0 to 20 kV/cm to support stable device operation under varying voltages. The applied magnetic field, from 0 to 10 T, resulted in increment in the linear, nonlinear and total absorption coefficients for all transitions.