Effective suppression of in localization and piezoelectric field in InGaN multi quantum-wells by growth on nano scale pyramidal facets

We have grown multi quantum wells (MQWs) with a peak wavelength of 570 nm on nano scale GaN hexagonal pyramid structures with facets formed by (11–22) planes by selective metal organic vapor phase epitaxy (MOVPE). The height, the bottom diameter and the pitch of the pyramid are 350 nm, 300 nm, and 500 nm, respectively. Photoluminescence (PL) measurements from 10 to 300 K show monotonic decrease in emission peak energy of the MQW with temperature increase without showing the typical S-shaped curve caused by In localization. Power dependent PL shows no noticeable blue shift cased by piezoelectric field screening effect. With a comparative study with MQWs on micro size pyramids, we find that elastic strain relaxation by nano size of the structure is responsible to the uniform In distribution and reduced piezoelectric field in addition to the semipolar growth plane.