Defect characterization of {101¯3} GaN by electron microscopy

Abstract

Advances in obtaining untwinned (10[Formula: see text]3)-oriented semi-polar GaN enable a new crystal orientation for the growth of green and red LED structures. We present a scanning electron microscopy study that combines the structural characterization of electron channeling contrast imaging with the optical characterization of cathodoluminescence hyperspectral imaging on a [Formula: see text] GaN layer. An extensive defect analysis revealed that the dominant defects consist of basal plane stacking faults (BSFs), prismatic stacking faults, partial dislocations, and threading dislocations. With a defect density of about an order of magnitude lower than in comparable. The optical properties of the defects have been characterized from 10 to 320 K, showing BSF luminescence at room temperature indicating a reduced density of non-radiative recombination centers in the as-grown samples compared to established semi- and non-polar orientations. Our findings suggest that growth along (10[Formula: see text]3) has the potential for higher radiative efficiency than established semi-polar orientations.

Cathodoluminescence studies of the optical properties of a zincblende InGaN/GaN single quantum well

“…These stripes are interrupted by regions of low CL intensity, indicating the presence of non-radiative recombination centres. Non-radiative recombination can occur at point defects, threading dislocations or SFs [20,[30][31][32][33][34][35][36][37]. Even though there are dark regions in the image, these are not regions of zero emission but of relatively low emission intensity compared to the surrounding material.…”

“…As discussed earlier, in the panchromatic CL images the regions associated with the pale stripes in the SE images appear dark. This can be explained by the optical properties of SFs in zb-GaN, which are significantly different from SFs in wz-GaN [31,36,40]. As a simplified picture, one can consider a SF in wz-GaN as a monolayer-wide zb insertion and vice versa.…”

Growth of N-Polar (0001) GaN in Metal–Organic Vapour Phase Epitaxy on Sapphire

“…The instrument has an aberration-corrected lens and allows measuring ECCI at 300,000× magnification. Thus, it could quantify even very high densities (see (10 13) GaN as a recent example [14]). The dislocation densities from ECCI were in the same order as the ones obtained by AFM.…”

Evaluations of the microstructures at the interface between the semipolar (101̄3) AlN epilayer and the m-plane (101̄0) sapphire substrate

“…Research works concerning the heteroepitaxial growth of semipolar {101 ¯3} epilayers on m-plane (101 ¯0) sapphire substrates have been reported. 12,[17][18][19][20][21][22][23][24][25] Based on the reports, it is possible to grow both N-polar (101 ¯3 ¯) and metal-polar (101 ¯3) III-nitride semipolar planes. (101 ¯3 ¯) GaN epilayers have been mainly grown by hydride vapor phase epitaxy (HVPE) and metalorganic chemical vapor deposition (MOCVD).…”

“…12,[17][18][19][20][21] On the other hand, (101 ¯3) GaN epilayers have been obtained by using a (101 ¯3) GaN template or a directional sputtered Al and AlN layer. [22][23][24][25] It is interesting to know what happens and how to control the lattice-polarity in {101 ¯3} epilayer growth. From this point of view, investigations of the microstructures at the interface between the epilayer and the substrate become important.…”