Abstract:
This study investigates the electronic and structural properties of In2O3 thin films on SiO2 and HfO2 substrates using synchrotron-based X-ray techniques, focusing on how oxygen vacancies (Vo) and hydroxide (−OH) incorporation influence threshold voltage (VTH) and field-effect mobility (μFE) in field-effect transistors (FETs). This study demonstrates that Vo significantly shifts threshold VTH and impacts the device’s electrical performance, aligning with results from TCAD simulations. In2O3 on HfO2 exhibits fewer Vo and greater stability compared to that on SiO2 , enhancing device lifetime. Structurally, In2O3 on HfO2 has a higher density (6.4 g/cm3 ) and lower interface roughness than In2O3 on SiO2 (5.9 g/cm3), where an intermixing layer is present at the In2O3/SiO2 interface. These structural differences contribute to a higher μFE for In2O3 on HfO2 (48 cm2 /V·s) compared to SiO2 (30 cm2 /V·s). Further annealing at 400°C can enhance density and interface quality in In2O3 on HfO2 , which improves its mobility to 115 cm2/V·s. These findings underscore the critical role of electronic and structural properties of In2O3 and its interface with the dielectric substrate in optimizing the performance and stability of oxide semiconductor FETs.
Keywords – In2O3, Threshold voltage, Mobility, HAXPES, XRR, XAS, GIWAXS