Abstract
In this study, we grow GaN film and investigated the influence of growing temperature and the flow rate of ammonia gas on the quality of the synthesized GaN thin film. Subsequently, we used the microwave plasma enhanced chemical vapor deposition to grow diamond film on GaN substrate. The objective of this study is to improve the thermal dissipation of a GaN substrate used in light emitting diode. In this regard, we fabricated the single and hybrid granular structured diamond films on GaN substrate. The hybrid diamond films are composed of diamond films with different grain size. We examined the morphology of the films by scanning electron microscope (SEM) and transmission electron microscope (TEM). The crystal structures of the samples were analyzed by X-ray diffractometer, and the bonding properties were characterized by Raman Spectroscopy. The results showed that the optimal conditions for growing GaN thin film is at 850 ℃ with 30 sccm ammonia gas flow. The film growth under these conditions has a smooth surface which is facilitate the growth of diamond films. For hybrid diamond film, we grow ultranano crystalline diamond (UNCD) as a bottom layer followed by grown nano crystalline diamond(NCD)/ UNCD hybrid structured diamond film. The properties of the as-synthesized NCD/UNCD hybrid diamond film were characterized by SEM, TEM and Raman.