Highly efficient yellow photoluminescence from {11–22} InGaN multiquantum-well grown on nanoscale pyramid structure

Abstract

InGaN/GaN multiquantum wells (MQWs) with a peak wavelength of 570 nm are grown on nanosize GaN hexagonal pyramid structures. Temperature dependent photoluminescence (PL) measurements from 10 to 300 K show a high integrated intensity ratio of 0.45. The emission energy of the MQW monotonically decreases with temperature increase, showing the absence of localized potential. Power dependent PL shows no noticeable blueshift caused by piezoelectric field screening effect. Comparative study of the PL results with those of the InGaN MQW on microsize pyramid show that nanosize pyramids play an important role in suppressing piezoelectric field in addition to the semipolar growth direction. We attribute the high luminescence efficiency of the MQW on nanosize pyramid structures to effectively suppressed piezoelectric field and potential localization.

Wafer-scale selective area growth of GaN hexagonal prismatic nanostructures on c-sapphire substrate

“…This method is essentially used in metalorganic vapor phase epitaxy (MOVPE) with patterned dielectric mask (SiO 2 or Si 3 N 4 ) to control the position and the size of GaN nanostructures as stripes [5], pyramids [5] and rods [6], and more recently in molecular beam epitaxy (MBE) using Ti patterned masks [7]. In MOVPE, SAG experiments are mostly reported on GaN layer template grown on c-sapphire substrate and usually result in pyramid-shaped nanostructures [8][9][10][11][12]. However, prismatic-shaped GaN structures have been observed for stripes and hexagonal nanostructures in SAG on bare c-sapphire [13,14].…”

Selective area growth of a- and c-plane GaN nanocolumns by molecular beam epitaxy using colloidal nanolithography

“…Though in this structure the effects of internal fields in the active region of the device (i.e. nanoLED) may be reduced compared with polar planes, the most effective solution is to grow along non-polar directions, either by growing core-shell heterostructures on the lateral nonpolar facets of otherwise polar NCs, or by growing axial heterostructures along nonpolar directions such as (m-planes) or [11][12][13][14][15][16][17][18][19][20] (a-planes). In both approaches, the internal fields are nominally zero.…”

“…the growth direction is parallel to [11][12][13][14][15][16][17][18][19][20]) by PAMBE on Ti masks. The vertical and lateral growth rates (anisotropy) are studied and compared with c-plane GaN NCs SAG.…”

“…Arrays of nanostructures grown by selective area growth (SAG) provide a much better homogeneity in terms of morphology, electrical and optical characteristics. SAG of III-nitride NCs [9-12] and other nanostructures [13,14], is generally performed on very thin metal (Ti, Mo) or dielectric (SiO 2, SiN) masks with an array of nanoholes.…”

“…Arrays of nanostructures grown by selective area growth (SAG) provide a much better homogeneity in terms of morphology, electrical and optical characteristics. SAG of III-nitride NCs [9-12] and other nanostructures [13,14], is generally performed on very thin metal (Ti, Mo) or dielectric (SiO 2, SiN) masks with an array of nanoholes.A relevant issue concerning optoelectronic devices based on III-nitrides is the presence of strong polarization fields that may reduce efficiency. This is the case in layers grown along the c-axis and, a huge effort is nowadays dedicated to the growth of high quality non-polar and semi-polar material [15], with a particular emphasis on non-polar LEDs [16].…”