Effect of Se-doping on deep impurities in AlxGa1−xAs grown by metalorganic chemical vapor deposition

Abstract

We have studied the effect of Se-doping on deep impurities in AlxGa1−xAs (x = 0.2∼0.3) grown by metalorganic chemical vapor deposition (MOCVD). Deep impurities in various Se-doped AlxGa1−xAs layers grown on GaAs substrates were measured by deep level transient spectroscopy and secondary ion mass spectroscopy. We have found that the commonly observed oxygen contamination-related deep levels at Ec-0.53 and 0.70 eV and germanium-related level at Ec-0.30 eV in MOCVD grown AlxGa1−xAs can be effectively eliminated by Se-doping. In addition, a deep hole level located at Ey + 0.65 eV was found for the first time in Se-doped AlxGa1-xAs when Se ≥2 × 1017 cm−3 or x ≥ 0.25. The concentration of this hole trap increases with increasing Se doping level and Al composition. Under optimized Se-doping conditions, an extremely low deep level density (Nt less than 5 × 1012 cm−3, detection limit) Al0.22Ga0.78As layer was achieved. A p-type Al0.2Ga0.8As layer with a low deep level density was also obtained by a (Zn, Se) codoping technique.