Seeded Growth of AlN Layers on Al‐ and N‐Polar AlN Seeds by the Cu–Al–Ca Solution Growth Method

Abstract

Herein, the growth behavior of aluminum nitride (AlN) layers on the Al‐polar and N‐polar surfaces of AlN seeds is investigated by the Cu–Al–Ca solution growth method. AlN layers with a thickness of 50–60 μm grow on N‐polar seeds in 5 h, whereas the thickness of the AlN layer on the Al‐polar seeds reaches approximately 35–50 μm. Optical microscopy, X‐ray diffraction, high‐resolution X‐ray diffraction (HRXRD), Raman spectroscopy, and photoluminescence (PL) spectroscopy are performed to investigate the morphology and crystal quality of the grown AlN layers. The N‐polar and Al‐polar surfaces show hillock growth, which is consistent with the hexagonal structure of AlN. However, the surfaces show differences in terms of hillock size (smaller on the N‐polar surface). The HRXRD rocking curves of (002) and (102) show full‐width at half‐maximum (FWHM) values of 160.25 and 33.53 arcsec, respectively. From Raman analysis, the FWHM values of the AlN layers on the N‐polar and Al‐polar seeds are 6.1 and 10.6 cm−1, respectively. The PL results show 310, 460, and 590 nm emission peaks of the AlN layer, which may be caused by oxygen impurity and VN (nitrogen vacancy) and Ali (aluminum gap).