Effect of Se-doping on Deep Impurities in Al_xGa_(1-x)As Grow by Metalorganic Chemical Vapor Deposition

摘要

We have studied the effect of Se-doping on deep impurities in Al_xGa_(1-x)As (x = 0.2～0.3) grown by metalorganic chemical vapor deposition (MOCVD). Deep impurities in various Se-doped Al_xGa_(1-x)As layers grown on GaAs substrates were measured by deep level transient spectroscopy and secondary ion mass spec-troscopy. We have found that the commonly observed oxygen contamination-related deep levels at E_C-0.53 and 0.70 eV and germanium-related level at E_C-0.30 eV in MOCVD grown Al_xGa_(1-x)s can be effectively eliminated by Se-doping. In addition, a deep hole level located at E_V + 0.65 eV was found for the first time in Se-doped Al_xGa_(1-x)As when Se ≥ 2 x 10~(17) 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 (N_t less than 5 x 10~(12) cm~(-3), detection limit) Al_(0.22)Ga_(0.78)As layer was achieved. A p-type Al_(0.2)Ga_(0.8)As layer with a low deep level density was also obtained by a (Zn, Se) co-doping technique.