Low Interface Trap Density 4H-SiC MIS Structure With SiO₂ Grown by Sub- 1000 °C Intermittent Spray Hydrated Oxidation (ISHO) for UV Sensor Applications

A novel methodology for producing low interface trap density metal-insulator–semiconductor (MIS) structures on 4H-SiC through sub-1000 °C intermittent spray hydrated oxidation (ISHO) is proposed in this work. The study investigates the material and electrical properties of the resulting SiO2 layer, demonstrating controllable oxide thickness ranging from approximately 3 to 7 nm within an hour, while minimizing carbon clustering at the interface. Electrical analysis reveals an exceptionally low interface trap density (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${D}_{\text {it}}$ </tex-math></inline-formula>) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 10^{{11}}$ </tex-math></inline-formula> cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{2}}\text {eV}^{-{1}}$ </tex-math></inline-formula> at flat-band voltage, highlighting the efficacy of the ISHO technique. In addition, the fabricated MIS devices showcase remarkable UV sensing capabilities, with photocurrent windows spanning about three orders of magnitude in amplification and having linear responsivity. Notably, even under high temperatures up to 100 °C, these devices maintain a photo-to-dark current ratio (PDCR) of approximately two to three orders of magnitude, demonstrating robustness in harsh operating conditions. This study underscores the potential of ISHO as a promising approach for high-quality oxide formation on 4H-SiC and emphasizes the suitability of 4H-SiC MIS devices for advanced UV sensor applications.