Photoluminescence properties of blue and green multiple InGaN/GaN quantum wells

The photoluminescence (PL) properties of blue multiple InGaN/GaN quantum well (BMQW) and green multiple InGaN/GaN quantum well (GMQW) formed on a single sapphire substrate are investigated. The results indicate that the peak energy of GMQW-related emission (PG) exhibits more significant "S-shaped" dependence on temperature than that of BMQW-related emission (P-B), and the excitation power-dependent carrier-scattering effect is observed only in the P-G emission; the excitation power-dependent total blue-shift (narrowing) of peak position (line-width) for the P-G emission is more significant than that for the P-B emission; the GMQW shows a lower internal quantum efficiency than the BMQW. All of these results can be attributed to the fact that the GMQW has higher indium content than the BMQW due to its lower growth temperature and late growth, and the higher indium content in the GMQW induces a more significant compositional fluctuation, a stronger quantum confined Stark effect, and more non-radiative centers.