Radiative recombination in a ZnTe p—n junction

Abstract

Radiative recombination (RR) in diodes created by a laser technique for doping of ZnTe crystals with Al donor impurity and having a p—n-junction with high electron concentration in an n-region ( n > 10 18 cm −3) have been investigated. Electroluminescence (EL) spectra under excitation by a forward-biased current with density up to 3 A/cm 2 at 80 and 300 K have been measured. Comparison of EL diode spectra and p-ZnTe substrate photoluminescence spectra lead to the conclusion that RR in the diodes occurs from an aluminium-doped region. A p—n-junction model with an intermediate i-region explains the change in the radiation spectra with the current density increase. At the current density of 1.8 A/cm 2 ( T = 80 K) RR takes place near an n-region, and an unknown band at 2.276 eV, which may be attributed to the radiative transitions between the aluminium donor and the valence band, has been observed in EL spectra. With the increase in the current density up to 3 A/cm 2, RR extends to the i-region, and the band at 2.269 eV, attributed to RR with the participation of aluminium and phosphorus atoms, dominates in EL spectra. For the first time, long-wave bands associated with participation in the radiative recombination of compensating complexes were not observed in EL spectra of diodes doped with donors.