Characteristics of hexagonal c-oriented titanium film as the template for GaN epitaxy on glass substrate by electron beam evaporation

Abstract

The highly c-oriented titanium (Ti) film is deposited on glass substrates by electron beam (EB) evaporation based on the study of effects of the substrate temperature (Ts) and deposition rate (Rd) on its properties. It is found that the Ts is the critical parameter and the Rd. is also important to the crystallization and surface morphology of EB-evaporated Ti film. The crystal orientation, grain size and surface smoothness are optimized if the migration time of Ti adatoms affected by the Rd. matches to their surface mobility affected by Ts. Besides, the Ti film thickness (Tf) is also exist an optimization range to achieve hexagonal c-oriented titanium film. The highly c-orientated (002) hexagonal and smooth Ti film, whose mean grain size and root mean square roughness are approximately 250nm and 1.54nm respectively, is realized with Ts of 300°C and Rd. of approximately 0.5nm/s when the thickness is 300nm. The single crystalline characteristics of individual Ti grains are demonstrated, and GaN grown on Ti film/glass substrate by molecular beam epitaxy at 530°C has the same epitaxial relationship to Ti film. It means that Ti film deposited by EB evaporation with appropriate Ts and Rd. can acts as the template of GaN epitaxy on glass substrate under the suitable thickness.