Electrodeposition of Gallium Nitride_Unraveling the Role of Precursors, Deposition Conditions, and Substrate Effects for Semiconductor Applications

Gallium nitride (GaN) is a wide-bandgap semiconductor noted for its remarkable optoelectronic and structural characteristics, rendering it a potential material for high-power, high-frequency, and optoelectronic device applications. This dissertation investigates the electrochemical synthesis of GaN thin films by potentiostatic and galvanostatic electrodeposition techniques using aqueous solutions of gallium nitrate (Ga(NO3)3), ammonium nitrate (NH4NO3), and auxiliary agents like potassium nitrate and urea. The main aim is to examine the essential elements affecting nitrogen incorporation and film shape while assessing electrochemical performance on various conductive substrates.A thorough investigation was performed to evaluate the impacts of electrodeposition duration, electrolyte pH, precursor molar concentrations, deposition technique (potentiostatic versus galvanostatic), and substrate type - specifically fluorine-doped tin oxide (FTO) and indium tin oxide (ITO). Protocols for post-deposition annealing and pre-treatment were also investigated. The surface morphology, elemental content, and structural properties of the deposited films were examined utilizing scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Despite efforts to enhance nitrogen incorporation, difficulties remained, especially due to spectrum overlap between nitrogen and tin in EDS measurement, along with restricted nitrogen retention at mildly acidic pH values. Significant variations in film growth behavior were noted between FTO and ITO substrates, indicating that substrate choice profoundly affects nucleation kinetics, interfacial charge transfer, and overall film uniformity. This study enhances the comprehension of GaN electrodeposition in aqueous environments and elucidates the intricacies of regulating nitrogen incorporation under ambient circumstances. It underscores the possibilities and constraints of low-temperature, scalable methods for GaN thin-film synthesis, providing insights into future avenues for environmentally friendly semiconductor fabrication procedures appropriate for advanced optoelectronic and power device technologies.