Photoluminescence studies of GaN epilayer–nanocrystals grown on γ-LiAlO2 substrate

✍ Scribed by C.H. Hsu; F.C. Kuo; C.S. Lee; Y.H. Chang; H.Y. Chao; J.H. Cheng; Ikai Lo; C.H. Hsieh; M.C. Chou

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 994 KB
• Volume: 40
• Category: Article
• ISSN: 1386-9477
• DOI: 10.1016/j.physe.2007.09.019

✦ Synopsis

We report the optical studies of the properties of M-plane GaN/c-plane GaN nanocrystal heterostructure on g-LiAlO 2 substrate grown by plasma-assisted molecular beam epitaxy. In this structure, in addition to the M-plane epilayer, nanocrystals grown in c-direction could also be observed in the step edges of the M-plane GaN terraces and the hexagonal basis of the g-LiAlO 2 substrate. X-ray diffraction (XRD) with peaks at 2y ¼ 32.2951, 34.6801 and 34.5051 are attributed to the M-plane GaN, LiAlO 2 and c-plane GaN, respectively. Two peaks were observed in the photoluminescence spectra at low temperature. The peak at 3.33 to 3.35 eV is attributed to the emission from c-plane GaN nanocrystals and the peak at 3.50 eV is attributed to the emission from M-plane GaN epilayers. The relative intensity of these peaks is position-dependent. In the area with higher concentration of the GaN nanocrystals the emission for the nanocrystals is stronger and vice versa. Cathodoluminescence shows that the emission peak at 3.33-3.35 eV is originated from the nanocrystals GaN.