Temperature-dependent electrical analysis of SnO2/4H-SiC Schottky diodes: role of post-deposition annealing

This study investigates the effects of post-deposition annealing on the morphological and electrical characteristics of vertical SnO₂/4H-SiC Schottky barrier diodes. Surface engineering is critical in tin oxide (SnO₂)-based devices to suppress interfacial defects and improve barrier uniformity, ultimately enhancing device reliability. Morphological and chemical analyses were conducted using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), while electrical performance was evaluated through current density–voltage (J–V), capacitance–voltage (C–V), and temperature-dependent J–V (J–V–T) measurements. The annealed devices exhibited enhanced film uniformity and reduced oxygen-vacancy states, contributing to improved interface quality. Compared to the as-deposited diodes, oxygen-annealed devices showed a higher Schottky barrier height (SBH), a lower ideality factor, and significantly reduced reverse leakage current. In addition, interface state density (N_SS) analysis revealed a notable reduction in trap states at the SnO₂/4H-SiC interface after annealing in the temperature range of 298–478 K, further supporting the observed improvements in carrier transport and barrier uniformity. Furthermore, Gaussian analysis of the SBH revealed decreased inhomogeneity, with the mean barrier height increasing from 1.14 to 1.31 eV and the standard deviation reducing from 0.24 to 0.20 V, indicating a more uniform metal/semiconductor interface. These results demonstrate that oxygen annealing is an effective strategy to enhance the thermal stability and electrical performance of SnO₂/4H-SiC diodes, making them promising candidates for next-generation power and sensing applications in harsh environments.