Semipolar GaInN/GaN light‐emitting diodes grown on honeycomb patterned substrates

Abstract

Excellent semipolar GaN material quality can be obtained by growing inverse GaN pyramids on full 2 inch c‐plane sapphire when combining the advantages of defect reduction via FACELO and selective area growth for faceted surfaces. The nearly defect free material is obtained by structuring the mask into a honeycomb pattern. When realizing full GaInN/GaN LED structures on those templates a relatively broad emission is observed during electroluminescence measurements. Furthermore, the dominant wavelength is found to be dependent on the applied current density. The pronounced shift is in good agreement with the wavelength shift along one single facet. Gas phase diffusion during the active area growth is believed to be the main reason for the varying indium content. The homogeneity could be influenced by changing the reactor pressure during the active area growth (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Spectrally and time‐resolved cathodoluminescence microscopy of semipolar InGaN SQW on (11$\overline {2} $2) and (10$\overline {1} $1) pyramid facets

“…Two different semipolar sample structures are under investigation consisting of an InGaN/GaN single quantum well (SQW) on top of {1122} facets of inverted pyramid surfaces [3] and {1011} facets of single pyramids [12], respectively (Fig. 1).…”

“…An excellent material quality for semipolar QWs was achieved using selective area growth (SAG) and facet controlled epitaxial lateral overgrowth (FACELO) [3]. For such micro-structured samples the characterization by a highly spatially resolved technique like cathodoluminescence (CL) is essential for a detailed and fundamental understanding of the microscopic optical properties [4][5][6].…”

Three‐dimensional GaN for semipolar light emitters

“…By introducing inverse GaN pyramids as an alternative method to produce semipolar GaN, we could demonstrate that high-quality material can be fabricated on large wafer sizes [27,28]. Inverse pyramids can be formed by structuring the templates using a hexagonally ordered dot-like pattern.…”

“…Dot-like mask openings allow the formation of pyramids with f1101g facets. Inverse GaN pyramids can feature f1122g or f1101g facets depending on the specific growth procedure [27,28]. Semipolar GaN grown on foreign substrates typically exhibits a bundle of defects including threading dislocations (TDs) and stacking faults.…”

Spectral features in different sized InGaN/GaN micropyramids

“…A possibility to fabricate semipolar surfaces is given by the selective area growth (SAG) in metal-organic vapor-phase epitaxy (MOVPE). By controlling the dielectric mask, fully three dimensional GaN structures can be fabricated, either as GaN stripes [9], pyramids [10][11][12] or inverted pyramids [12,13]. Apart from the favourable semipolar facet for the field reduction and the In-incorporation, also the pyramidal structures exhibit improved light extraction.…”