Polar and semipolar (112) InAlN layers grown on AlN templates using MOVPE

Abstract

We report on metalorganic vapor phase epitaxial growth of InAlN layers on (0001) and (11true2‾2) AlN templates at different temperatures (725–800 °C). The indium content (8.0–15.2%) of the (11true2‾2) InAlN layers was found to be lower compared to that for the (0001) layers (9.0–23.0%). The higher indium content of the (0001) layers was attributed to a high density of small hillocks and a larger degree of relaxation. The small hillocks on the (0001) layer surface acted as quantum‐dot‐like structures that caused a stronger emission at longer wavelength compared to weaker emission at shorter wavelength from a “bulk” layer underneath. A large Stokes‐shift of about 300 and 480 meV was observed for the (0001) and (11̅22) layers, respectively. The larger shift of the (11true2‾2) layers was attributed to a higher degree of localization. The larger degree of localization and higher unintentional oxygen incorporation enhanced the luminescence intensity of the (11true2‾2) layers compared to that for the (0001) layers.

Epitaxial growth of semipolar InAlN films on yttria-stabilized zirconia

“…Figure 6 shows an SEM image of In 0.8 Al 0.2 N(1 103) grown on InN(1 103)/YSZ(113). Striations along the direction perpendicular to InAlN [11 20] are observed, which are similar to those on semipolar InAlN surfaces grown by other techniques [18,19].…”

“…However, semipolar growth of InAlN suffers from two main obstacles, namely, lack of suitable substrates and immiscibility between InN and AlN . Consequently, there are only a few reports on growth of semipolar InAlN films . The former issue can be overcome by utilizing yttria‐stabilized zirconia (YSZ) which possesses lattice match with high In‐content InAlN; thus, it is a promising candidate for growing high In‐content semipolar InAlN.…”

Growth and Microstructure Analyses of Semipolar AlInN Epitaxial Layers on a Fully Relaxed Semipolar {112¯2} GaInN/GaN/m‐plane Sapphire Template

“…This information is consistent with the surface observation results shown in Figure 2. Then, the TEM images also revealed that the BSFs in the GaN (0001) plane, [ 29,30 ] which are observed as lines parallel to the [] direction, propagated up to the top AlInN layer through the GaInN layer. This information agrees with the result of the XRD‐RSMs shown in Figure 7.…”

“…This indicates the existence of basal-plane stacking faults (BSFs) in the (0001) lattice planes. [29,36] On the other hand, the diffraction peaks from AlInN layers were observed to greatly broaden along the TEM study was carried out to analyze their crystal mosaicity in more detail.…”

“…layers can be formed on the fully relaxed semipolar GaInN layers, they will become highly promising structural components for long-wavelength visible GaN LDs. On the other hand, although some researchers have reported the growth of nonpolar [7,8,[24][25][26][27] and semipolar [26][27][28][29] AlInN layers, there have been no reports focusing on the growth of thick and flat-surface AlInN epitaxial layers with high-InN mole fraction. Therefore, in this study, we attempted to grow AlInN layers with submicrometer thicknesses and high-InN mole fractions using a fully relaxed semipolar GaInN template and to evaluate their crystal qualities including the surface flatness.…”