Terahertz Luminescence and Absorption under Impurity Breakdown in Quantum Wells and Strained Semiconductor Layers

We present the results of THz luminescence investigations in structures with Si-doped quantum wells and Be-doped GaAsN layers under strong lateral electric field. The peculiar property of these structures is the presence of resonant impurity states which arise due to dimensional quantization in quantum wells and due to built-in strain in GaAsN epilayers. The experimentally obtained THz emission spectra consist of the lines attributed to intra-center electron transitions between resonant and localized impurity states and to the electron transitions involving the subband states. Absorption of THz radiation and its temperature dependence was also studied in structure with tunnel-coupled quantum wells at equilibrium conditions and under electric field.