Direct evidence of nanoscale carrier localization in InGaN/GaN structures grown on Si substrates

InGaN insertions in a GaN matrix provide efficient lateral carrier localization on a nanoscale level as established by nonresonant and resonant time-resolved photoluminescence studies. In the case of resonant excitation the line width is defined by the excitation laser pulse only, while the decay characteristic remains the same as that in the case of nonresonant excitation. No spectral shift of the resonant photoluminescence peak which could be caused by reducing the piezoelectric screening of nonequilibrium carriers was found. This demonstrates that only one electron-hole pair may be generated in a compositional domain, which must have a strong localization and wide energy spacing.