Microstructural study of MBE-grown ZnO film on GaN/sapphire (0001) substrate

摘要

Single crystalline ZnO film is grown on GaN/sapphire (0001) substrate by molecular beam epitaxy. Ga_20_3is introduced into the ZnO/GaN heterostructure intentionally by oxygen-plasma pre-exposure on the GaNsurface prior to ZnO growth. The crystalline orientation and interfacial microstructure are characterizedby X-ray diffraction and transmission electron microscopy. X-ray diffraction analysis shows strong c-axispreferred orientation of the ZnO film. Cross-sectional transmission electron microscope images revealthat an additional phase is formed at the interface of ZnO/GaN. Through a comparison of diffraction pat-terns, we confirm that the interface layer is monoclinic Ga_2O_3and the main epitaxial relationship should be(0001 )z_no//(001)G_(a2)о_з//(0001 )CaN and [2-1-1o]z_nо/401o]co_2О_3Н[1оICaN.