Transient spectroscopy of defects with deep levels in AlGaAsSb/GaAs p–i–n--heterostructures

High-voltage gradual p⁰–i–n⁰ junctions of Al_xGa_1–xAs_1–ySb_y with y up to 15%, capable of absorbing radiation with a wavelength of 1064 nm, grown on GaAs substrates by liquid-phase epitaxy due to autodoping with background impurities, have been studied. The composition of the liquid phase and the growth temperature interval were chosen such that the content of aluminum compounds x along the thickness of the epitaxial layer monotonically decreased from the set values of about 34% to units of percent at the surface of the layer, and the content of antimony compounds y increased, while the width of the band gap gradually decreased from the substrate to the surface of the lightly doped layer and reached the desired values ~1.16 eV. Using the methods of capacitance-voltage characteristics and deep level transient spectroscopy, the configuration-bistable DX centers of Si and Se/Te donor impurities were identified in them. The absence of deep levels associated with dislocations was found in the studied heterostructures. The effective lifetime of minority carriers in the base layers of the Al_xGa_1–xAs_1–ySb_y/GaAs diode was determined using the method of reverse recovery of diodes. Assuming that the lifetime of minority carriers is determined mainly by the capture of holes at the acceptor–like deep DX-level of Si, the value of the capture cross section of holes at the DX-level was estimated. The capture cross section turned out to be equal to 6 × 10^–15 cm^–2.