Nanostructures and carrier localization behaviors of green-luminescence InGaN/GaN quantum-well structures of various silicon-doping conditions

The results of photoluminescence (PL), detection-energy-dependent photoluminescence excitation (DEDPLE), excitation-energy-dependent photoluminescence (EEDPL), and strain state analysis (SSA) of three InGaN/GaN quantum-well (QW) samples with silicon doping in the well, barrier and an undoped structure are compared. The SSA images show strongly clustering nanostructures in the barrier-doped sample and relatively weaker composition fluctuations in the undoped and well-doped samples. Differences in silicon doping between the samples give rise to the differences in DEDPLE and EEDPL spectra, as a result of the differences in carrier localization. In addition, the PL results provide us clues for speculating that the S-shaped PL peak position behavior is dominated by the quantum-confined Stark effect in an undoped InGaN/GaN QW structure.