Epitaxial lateral overgrowth of a-AlN layer on patterned a-AlN template by HT-MOVPE

Epitaxial lateral overgrowth (ELO) of a-plane AlN (a-AlN) has been carried out on patterned a-AlN by high-temperature metal-organic vapor phase epitaxy (HT-MOVPE). The a-AlN templates were grown on +0.5° off r-plane sapphire. The ELO a-AlN layers were found to have coalesced well on the a-AlN templates with trenches formed along 〈101¯0〉, while the ELO a-AlN layers were not coalesced on the a-AlN templates with trenches formed along 〈0001〉. Both the a-AlN template and the coalesced ELO a-AlN layer were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), cathodoluminescence (CL) and transmission electron microscopy (TEM). Consequently, it was found that the ELO technique is useful for improving the crystalline quality of a-AlN layer by HT-MOVPE.