Influence of GaN column diameter on structural properties for InGaN nanocolumns grown on top of GaN nanocolumns

Abstract

The influence of GaN column diameter DGaN on structural properties was systematically investigated for InGaN nanocolumns (NCs) grown on top of GaN NCs. We demonstrated a large critical layer thickness of above 400 nm for In0.3Ga0.7N/GaN NCs. The structural properties were changed at the boundary of DGaN=D0 (∼120 nm). Homogeneous InGaN NCs grew axially on the GaN NCs with DGaN≤D0, while InGaN-InGaN core-shell structures were spontaneously formed on the GaN NCs with DGaN>D0. These results can be explained by a growth system that minimizes the total strain energy of the NCs.

Effects of Introduction of InGaN Quantum Structures on Structural and Optical Properties of InGaN Nanocolumns

“…Here, the specific diameters for the InGaN NCs and InGaN/GaN SQSs are denoted as D 0 NC and D 0 SQS , respectively ( D 0 NC = 120–130 nm and D 0 SQS = 62–76 nm). D 0 NC relates to the critical column diameter D c at which the critical layer thickness diverges to infinity when D GaN ≤ D c . Therefore, D 0 SQS cannot be determined based on D c .…”

“…The In‐rich InGaN core grows axially along the c‐axis and a Ga‐rich InGaN shell forms outward, as observed in Refs. and . Hence, each InGaN/GaN SQS comprises an In‐rich InGaN QD at the center and a Ga‐rich semipolar InGaN QW.…”

“…The emission efficiency of InGaN decreases with an increase in the emission wavelength, but it can be improved by introducing nanostructures to the material . GaN‐based nanocolumns (NCs), also called nanowires, nanorods, and nanopillars, show desirable emission properties because they have low threading/misfit dislocation densities, high light‐extraction efficiencies, and strain‐relaxation effects from free lateral surfaces . To fabricate high‐emission‐efficiency NC‐based optical devices, a comprehensive understanding of the effects of the nanostructures on the optical properties is important.…”

“…We previously reported the fabrication of uniform GaN‐based NC arrays via a Ti‐mask‐based SAG technique . The structural and optical properties of In 0.3 Ga 0.7 N NCs grown on top of GaN NCs were evaluated as functions of the GaN column diameter, D GaN . The structural and optical properties changed abruptly at the specific diameter D GaN = D 0 ( D 0 ≈ 120–130 nm for In 0.3 Ga 0.7 N/GaN NCs).…”

Comparison of surface plasmon polariton characteristics of Ag- and Au-based InGaN/GaN nanocolumn plasmonic crystals

“…14,18,20) Furthermore, two-dimensional PlCs can be introduced by metal deposition onto periodic GaN nanostructures, such as regularly arrayed nanocolumns (NCs). InGaN-based NCs, which are also called nanowires, have attracted great attention owing to their nanocrystalline and nanostructural effects, such as their dislocation-free nature, [21][22][23][24] low strain energy, [25][26][27][28][29] and efficient light extraction. 30,31) We have developed uniform InGaN/GaN NC arrays via the Ti-mask selective-area growth technique.…”