InGaN/GaN multiple quantum wells (MQWs) with [0001], <11.2>, and <11.0> orientations have been fabricated by means of the re-growth technique on patterned GaN templates with striped geometry, normal planes of which are (0001) and {11.0}, on sapphire (0001) substrates. It was found that photoluminescence intensity of the {11.2} QW is the strongest among the three QWs, and its internal quantum efficiency was estimated to be as large as about 40% at room temperature. The radiative recombination lifetime of the {11.2} QW was about 0.39 ns at 14 K, which was 3.8 times shorter than that of conventional c-oriented QWs emitting at a similar wavelength. These findings are well explained by the high internal quantum efficiency in the {11.2} QW owing to the suppression of piezoelectric fields.

Dynamical behavior of radiative recombination has been assessed in the In0.20Ga0.80N (3nm)/In0.05Ga0.95N (6 nm) multiple quantum well (MQW) structure by means of transmittance (TR), electroreflectance (ER), photoluminescence excitation (PLE) and time-resolved photoluminescence (TRPL) spectroscopy. The PL at 20 K was mainly composed of two emission bands whose peaks are located at 2.920 eV and 3.155 eV. The ER and PLE revealed that the transition at 3.155 eV is due to the excitons at quantized level between n=1 conduction and n=1 A(Γ9υ) valence bands, while the main PL peak at 2.920 eV is attributed to the excitons localized at the trap centers within the well. The TRPL features were well understood as the effect of localization where photo-generated excitons are transferred from the n=1 band to the localized centers, and then are localized further to the tail state. The origin of the localized centers were attributed to the In-rich region in the wells acting as quantum dots which could be observed by transmission electron microscopy (TEM) and energy-dispersive X-ray microanalysis (EDX).