A Study on the Preferred Orientation Characteristics of AlN Thin Films by Reactive Evaporation Method using NH₃

Aluminum nitride(AlN) is a compound (III-V group) of hexagonal system with a crystal structure. Its Wurzite phase is a very wide band gap semiconductor material. It has not only a high thermal conductivity, a high electrical resistance, a high electrical insulating constant, a high breakdown voltage and an excellent mechanical strength but also stable thermal and chemical characteristics. This study is on the preferred orientation characteristics of AlN thin films by reactive evaporation using NH₃. We have manufactured an AlN thin film and then have checked the crystal structure and the preferred orientation by using an X-ray diffractometer and have also observed the microstructure with TEM and AlN chemical structure with FT-IR. We can manufacture an excellent AlN thin film by reactive evaporation using NH₃ under 873 K of substrate temperature. The AlN thin film growth is dependent on Al supplying and NH₃ has been found to be effective as a source of N₂. However, the nuclear structure of AlN did not occur randomly around the substrate a particle of the a-axis orientation in fast growth speed becomes an earlier crystal structure and is shown to have an a-axis preferred orientation. Therefore, reactive evaporation using NH₃ is not affected by provided H₂ amount and this can be an easy a-axis orientation method.