Defects with Deep Levels in High-Voltage Gradual p–i–n Heterojunctions AlGaAsSb/GaAs

High-voltage gradual p⁰–i–n⁰ junctions of Al_xGa_{1 – x}As_{1 – y}Sb_y with x ~ 0.24 and y ~ 0.05 in the i‑region were studied using capacitance-voltage characteristics method and transient spectroscopy of deep levels. It has been established that the effective recombination trap in them is the DX-center of the Si donor impurity, with a thermal activation energy E_t = 414 meV, a capture cross section σ_n = 1.04 × 10^–14 cm², and a concentration N_d = 2.4 × 10¹⁵ cm^–3. In the heterostructures studied, there were no deep levels associated with dislocations.