A systematic and quantitative analysis of the bulk and interfacial properties of the AlSiO dielectric on N-polar GaN using capacitance-voltage methods

Abstract

The bulk and interfacial properties of aluminum silicon oxide (AlSiO) on N-polar GaN were investigated systematically employing capacitance-voltage (C-V) methods on metal-oxide-semiconductor capacitors using a thickness series of the AlSiO dielectric. The fixed charge density, electron slow trap density, and electron fast trap density located near the interface were extracted to be -1.5 × 1012 cm-2, 3.7 × 1011 cm-2, and 1.9 × 1011 cm-2, respectively. Using ultraviolet (UV) assisted C-V methods, an average interface state density of ∼4.4 × 1011 cm-2 eV-1 and a hole trap concentration in bulk AlSiO of ∼8.4 × 1018 cm-3 were measured. The negative fixed interface charge makes it favorable to achieve a normally off GaN transistor. The analysis presented in this paper provides a systematic and quantitative model to study the properties of oxide dielectrics on wide bandgap (WBG) semiconductors, which can promote the development of metal-oxide-semiconductor-based WBG semiconductor devices.