Simultaneous growth of GaN/AlGaN quantum wells on c-, a-, m-, and (20.1)-plane GaN bulk substrates obtained by the ammonothermal method: Structural studies

•GaN/AlGaN quantum wells were obtained on GaN ammonothermal substrates with various crystallographic orientations.•GaN/AlGaN epilayers were grown on c-, m-, a-, and (20.1)-plane GaN substrates by MOCVD.•The influence of substrate orientation on the quality of GaN/AlGaN epilayers has been demonstrated.•The MOCVD growth conditions have been optimized for c-plane GaN/AlGaN epilayers.•Structural properties have been compared for c-, m-, a-, and (20.1)-plane GaN/AlGaN epilayers.

GaN/AlGaN quantum wells (QWs) were grown by metal–organic vapor phase epitaxy (MOVPE) on c-, a-, m-, and (20.1)-plane GaN substrates obtained by the ammonothermal method in the same MOVPE process, i.e. a process with growth parameters optimized for c-plane GaN templates. The structural properties of GaN/AlGaN QWs were carefully investigated by high angle annular dark field scanning transmission electron microscopy. Sharp GaN/AlGaN interfaces were seen for QWs grown on the c-, a-, and m-plane GaN substrates, but very rough interfaces with {1-100} and {1-101} facets were observed on the (20.1)-plane GaN substrate. In addition, the Al-rich region of AlGaN and GaN transition was identified for each of the GaN/AlGaN QW samples deposited in this process. The thickness and composition of this region varied with the crystallographic orientation of GaN substrates.