Diamond and aluminum nitride thin films: Synthesis, properties, and some device applications

The technology of crystal growth has significantly improved in recent decades. Chemical vapor deposition (CVD) techniques have been used to grow wide band gap materials due to their simplicity, scalability, and acceptance by industry. In this work, diamond and aluminum nitride (AlN) films were grown by CVD. Growth conditions and the resulting film characteristics of these two thin films were investigated.;Current CVD techniques make it possible to grow polycrystalline diamond thin films on non-diamond substrates (e.g. silicon, molybdenum, ;Aluminum nitride thin film was grown on silicon substrates with RF substrate heating using CVD and AlCl;Material diagnosis tools, such as X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM) were used to characterize the diamond and aluminum nitride thin films. The results indicate that the thin films grown were good quality, well crystallized material.;The substrate temperature plays a very important role in the HFCVD diamond deposition process. In order to improve film surface uniformity and morphology, a computer simulation of the HFCVD process based on radiative heat transfer from the filament to the substrate and the heat loss by the substrate, was performed. By utilizing results from this simulation, we modified the shape of the filament and improved the uniformity of the substrate temperature.;Ion bombardment was used to modify diamond and AlN films. Smoothing or etching of the CVD films was also achieved by this technique. Electrical characteristics of the bombarded thin films was investigated. Effect of mechanical stress on current-voltage characteristics and the photoresponse of diamond and AlN based diodes are also discussed in the following chapters.