A High-Temperature Stable Ohmic Contact Process on Lightly Doped n-Type 4H-SiC Based on a W/C Multilayer Structure

In this paper, we propose a novel method for fabricating high-thermal-stability Ohmic contacts on 4H-SiC using a low-doping-concentration (2.5 × 10¹⁵ cm^-3) n-type epitaxial layer. The method employs a tungsten/carbon (W/C) multi-nanolayer stacked structure combined with a 1200 °C rapid thermal process (RTP). The fabricated Ohmic contacts achieve a specific contact resistance ρ_c of 2.53 × 10^-4 Ω·cm² at room temperature (RT) and 1.29 × 10^-5 Ω·cm² at 500 °C. Furthermore, they exhibit excellent long-term operational reliability, maintaining stable performance during a 500 °C high-temperature test for 100 h in air without significant degradation. This method eliminates the need for ion implantation, avoiding lattice damage and reducing fabrication cost. The demonstrated thermal stability is highly desirable for elevated-temperature SiC-based devices and integrated circuits.