Fabrication and Characterization of GaAs MOS Capacitor With CVD Grown Polymer-Based Thin Film as a Gate Dielectric

GaAs Metal-Oxide-Semiconductor (MOS) capacitor using a polymer-based thin film as a gate dielectric has been fabricated and electrically characterized. The influence of the atomic concentration of oxygen in the dielectric films on the capacitance-voltage (C-V) and current-voltage characteristics of the MOS capacitors has been thoroughly investigated. The GaAs MOS capacitor obtained at low concentration of oxygen showed an almost ideal MOS capacitor behavior. The density of the interface traps extracted from the conductance-frequency measurement was found to be as low as 9.7 x 10⁹ eV^-1 cm^-2. In addition, the MOS capacitor exhibits very low leakage current (6.6 10^-9 A/cm² at -1 V) and relatively high breakdown voltage (2.05 MV/cm). These characteristics make polymer-based thin films very attractive as a passivation layer and a gate dielectric for GaAs MOSFET. The ability to tune the polymer through chemical synthesis and polymer functionalization makes CVD grown polymer-based thin films very promising for the passivation of virtually any semiconductor surface.