This study investigated a variety of electrically insulating materials for potential use as a gate dielectric in thin-film transistor applications. The materials that were investigated include silicon dioxide and oxynitride films deposited using PECVD and LPCVD techniques. Silicon source materials included tetraethylorthosilicate (TEOS) and silane (SiH₄). Oxygen sources included diatomic oxygen (O₂) and nitrous oxide (N ₂O). The optical, electrical, and material properties of the dielectrics were analyzed using Variable Angle Spectroscopic Ellipsometry (VASE), Fourier Transform Infrared Spectroscopy (FTIR), Capacitance-Voltage (C-V) analysis and current-voltage (I-V) analysis. Transistors were also fabricated at low temperatures with different gate dielectrics to investigate the impact on device performance. While a deposited gate dielectric is intrinsically inferior to a thermally grown SiO₂ layer, an objective of this study was to create a high quality gate dielectric with low levels of bulk and interface charge (Q_it & Q_ot∼1x10¹⁰ cm ²); this was achieved.