Properties of nanopillar structures prepared by dry etching of undoped GaN grown by maskless epitaxial overgrowth

Microcathodoluminescence spectra evolution for planar and nanopillar multiquantum-well GaN-based structures as a function of electron irradiation dose

“…The increased peak intensity in the nanopillar sample is in line with previous observations and comes from enhanced light extraction efficiency due to additional scattering by the nanopillar pattern and, partly, from improved internal quantum efficiency (IQE). 28,29 (We have shown that the nanopillar formation by dry etching is random and not correlated with dislocation distribution. As a result, some of the nanopillars do not contain dislocations in their core.…”

“…A detailed description of the growth procedure and nanopillars formation procedure can be found in Refs. [27][28][29]. The advantages of nanopillar LEDs compared to their planar counterparts have been described in multiple papers (see, e.g., recent reviews in Refs.…”

III‐Nitride Nanowires as Building Blocks for Advanced Light Emitting Diodes

“…For the starting dislocation density of some 10 8 cm −2 (current state‐of‐the‐art in GaN growth) and the nanopillars dimensions of about 100 nm (the usual range of dimensions at which the process is aimed) the percentage of defective nanopillars will be below 10% and thus not really inferior to the situation with the nanopillar structures prepared by the bottom‐up growth approach. Experimental studies performed on thick GaN films prepared by pendeo epitaxy and having the dislocation density close to 8 × 10 8 cm −2 in the vertical growth seed regions and an order of magnitude lower in the wing regions showed that the Ni balls mask formation is not correlated with the dislocation density underlying the Ni/SiO 2 film as illustrated by Figure from our paper . The image in Figure (a) clearly displays the seed regions with a high density of dark spots/dislocations interspersed with the wing regions with low density of dark spots/dislocations.…”

“…Naturally, with such a method of NWs fabrication some spread in the diameter of NWs and the local NWs’ array density is unavoidable. These variations have been studied quantitatively in our paper . It was found that the typical spread of the NWs’ diameter is quite low, with the size spread reasonably described by Gaussian distribution.…”

“…The method is illustrated by Figure . A practicable recipe producing a dense matrix of NWs with the density around 10 9 cm −2 and the typical NWs’ diameter close to 200 nm is described in our papers . In brief, the sequence of operations can be like this.…”