Characterization of High Quality Epitaxially Grown Diamond Thin Films

Single crystal diamond is an ideal material for high power, high frequency, and high temperature applications due to its superior electrical and thermal properties when compared to other wide bandgap semiconductors. Apart from electrical and thermal properties, diamond exhibits intriguing optical and spin characteristics due to its ability to host a multitude of impurities and vacancy centers such as nitrogen-vacancy (NV), silicon-vacancy (SiV) centers, etc. thus making it suitable for various quantum applications. High quality single crystalline diamond thin films with excellent control over the doping or impurity concentration is much desired. Here, heteroepitaxial and homoepitaxially grown diamond thin films are characterized and a parallel has been drawn by contrasting the quality and characteristics of these films. Heteroepitaxial diamond was grown via hot-filament CVD (HFCVD) technique, on (0001) and (11-20) oriented sapphire substrates with Ni buffer (Magnetron Sputtering) and Q-carbon (PECVD) seed layer. Both Ni and diamond were grown using domain matching epitaxy (DME) paradigm. A very thin Q-carbon seed layer (10-20nm) deals with the nucleation barrier. Homoepitaxial diamond thin films were grown in a microwave plasma enhanced CVD (MWPECVD) reactor on HPHT synthesized diamond substrates, and provided by Blue Wave Semiconductors Inc. Line width of diamond peaks obtained by Raman and PL measurements, HR-XRD rocking curves establish the quality of the films. The presence of impurities can be found by other characteristic peaks in Raman and PL measurements. High-resolution SEM images show the surface features. The surface roughness and depth profiling were obtained from AFM analysis. Heterostructure growth and orientation relationships were determined from cross-sectional HRTEM, EBSD analysis and XRD phi scans.