Reduction in the concentration of cation vacancies by proper Si-doping in the well layers of high AlN mole fraction Al_xGa_(1-x)N multiple quantum wells grown by metalorganic vapor phase epitaxy

摘要

Appropriate-amount Si-doping in the well layers significantly improved the luminescence efficiency of Al_(0.68)Ga_(0.32)N/Al_(0.77)Ga_(0.23)N multiple quantum wells. To understand the mechanisms, spatio-time-resolved cathodoluminescence measurements and self-consistent Schrodinger-Poisson calculations were carried out. The increase in the luminescence lifetime at room temperature, which reflects the decrease in the concentration of nonradiative recombination centers (NRCs), was correlated with increased terrace width of Si-doped wells. The results suggest the importance of H_3SiNH_2 doping-reactant formation that gives rise to enhanced decomposition of NH_3 and provides wetting conditions by surface Si-N bonds, which reduce the total energy and concentration of NRCs composed of cation vacancies.