Effects of post-deposition annealing on BaTiO₃/4H-SiC MOS capacitors using aerosol deposition method

Abstract

High-k oxide materials for metal–oxide–semiconductor field-effect transistors and metal–oxide–semiconductor (MOS) structure on SiC have been explored to enhance SiC-based device performance. In our experiments, the MOS capacitors with a high-k barium titanate (BaTiO₃) insulating layer were fabricated using the aerosol deposition (AD) method, and post-deposition annealed in O₂ atmospheres. We examined the effects of post-deposition annealing on the BaTiO₃ films and their impact on the surface and electrical characteristics of MOS capacitors. The crystallinity and surface morphologies of the BaTiO₃ films were analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy. We conducted the electrical analysis through current–voltage and capacitance–voltage (C–V) measurements. The post-deposition annealing process effectively reduced the gate leakage current of BaTiO₃/4H-SiC and elevated the rectification ratio from 9.12 × 10⁸ to 1.61 × 10⁹. C–V characteristics were measured at 1 MHz to investigate the oxide defect charges inside the MOS capacitors. Near-interface trap density (${N}_{{\text{it}}}$) decreased from 9.10 × 10¹¹ to 5.53 × 10¹¹ cm⁻² due to post-annealing, which diminished flat band voltage hysteresis. Fixed oxide charge density (${Q}_{{\text{f}}}$) also diminished from 4.00 × 10¹¹ to 3.58 × 10¹¹ cm⁻², and the oxygen vacancies were compensated by the oxygen atoms introduced from the O₂ during the post-deposition annealing. Our findings suggest that the post-deposition annealed process significantly influences surface and electrical properties during BaTiO₃ thin film deposition using AD.