Study of Wide-Band Gap Oxide and Nitride-Based Semiconductors: Characterization and Device Physics

The increasing need for short wavelength material alongside high-power and high-frequency devices have encouraged a strong wave of research amongst the scientific community. While the breakthroughs in the high-quality growth of these materials have been achieved demonstrating promising device applications, further research is warranted in terms of control of electronics structure, improvement in crystalline quality, better control over defects and impurities, more efficient device designs etc. This dissertation work aims at characterizing & understanding the dynamics and the underlying physics of wide band gap oxide and nitride-based semiconductors to push further the potential applications of these materials based devices. In the first part of the study, a simple and efficient Ar-plasma treatment is proposed to passivate surface traps or defects to significantly improve the near-band-edge (NBE) emission from ZnO nanostructures. Furthermore, improved carrier dynamics with faster relaxation time due to surface treatments from these oxide nanostructures have been studied and analyzed in detail. Effect of morphology, as well as surface treatment on the lasing properties from these structures, have been presented alongside. Another synergistic study of ZnO co-existing with In2O3 nanostructures have been reported which encompasses several elemental and optical characterization techniques to analyze this ensemble of nanostructures. In the second part of the work, Raman analysis of a very short period AlN/GaN-based superlattice structure has been studied in detail to understand the vibrational properties. Furthermore, the behavior the superlattice under the impact of high-excitation and high-temperature, both of which are the operating condition of high power device has been addressed.