Band-to-band character of photoluminescence from InN and In-rich InGaN revealed by hydrostatic pressure studies

摘要

The authors studied the hydrostatic pressure dependence of photoluminescence (PL) from In-rich In_xGa_(1-x)N with In contents x between 0.58 and 1.00. The observed PL pressure coefficients of 20-25 meV/GPa agree well with previously reported experimental and theoretical values of the band gap pressure coefficient, from which they conclude that band-to-band recombination is responsible for PL emission. This contrasts with earlier reports, where relatively low PL pressure coefficients were interpreted as evidence of the involvement of strongly localized states in the PL emission. The reported observation of band-to-band recombination in In-rich InGaN is encouraging from the point of view of the construction of light emitters, since band-to-band recombination is more efficient than recombination via localized states. Furthermore, significant bowing of the band gap pressure coefficient in In-rich In_xGa_(1-x)N, as predicted by theory, is confirmed.