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<p>Silicon carbide (SiC) single-crystal substrates, as core materials for wide-band-gap semiconductor devices, exhibit critical optical and mechanical stability under high-temperature environments, which decisively influences the reliability of aerospace, deep-space exploration, and high-temperature sensor systems. This study systematically investigates the evolution of optical properties and key mechanical parameters (elastic modulus and linear thermal expansion coefficient) of high-purity 4H–SiC single-crystal substrates within a temperature range of 25–1600&#xa0;°C, elucidating the impact of extreme thermal conditions on the material’s intrinsic characteristics. High-temperature treatments were conducted in an air atmosphere at 600–1600&#xa0;°C, and the effects on optical performance (transmittance) and surface morphology were analyzed using ultraviolet–visible–near-infrared spectrophotometry (UV–Vis–NIR) and scanning electron microscopy (SEM). Experimental results reveal that: (1) at temperatures ≤ 600&#xa0;°C, the average transmittance of SiC in the 350–2000&#xa0;nm spectral range (below 65%) remains statistically consistent with the as-received substrate; (2) when the temperature rises to 1000&#xa0;°C, the transmittance in the Vis–NIR region (400–1100&#xa0;nm) significantly improves by 20%-30%, achieving a peak transmittance of 95%; (3) at 1600&#xa0;°C, a grayish amorphous silicon–oxygen oxide layer (~ 890&#xa0;nm thick) forms on the substrate surface, leading to a decline in full-spectrum transmittance and the emergence of characteristic thin-film interference patterns. Mechanical testing demonstrates that the linear thermal expansion coefficient increases at rates of 6 × 10⁻⁹ /°C, respectively, while the elastic modulus decreases at a rate of 0.034 GPa/°C between 600 and 1600&#xa0;°C. This research provides critical process optimization guidelines for SiC-based high-temperature applications, thermal management for high-power semiconductor devices, and structural design in extreme environments.</p>

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Study on optical and mechanical properties of SiC single-crystal substrate at high temperature

  • 期刊论文

  • 发表日期：

    2025年7月2日

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  • Jintao Xu,
  • Pan Gao,
  • Wenkai Wang,
  • Weiyi He,
  • Shengnan Jiang,
  • Xiuhong Pan,
  • Chunjun Liu,
  • Xuechao Liu

摘要

Silicon carbide (SiC) single-crystal substrates, as core materials for wide-band-gap semiconductor devices, exhibit critical optical and mechanical stability under high-temperature environments, which decisively influences the reliability of aerospace, deep-space exploration, and high-temperature sensor systems. This study systematically investigates the evolution of optical properties and key mechanical parameters (elastic modulus and linear thermal expansion coefficient) of high-purity 4H–SiC single-crystal substrates within a temperature range of 25–1600 °C, elucidating the impact of extreme thermal conditions on the material’s intrinsic characteristics. High-temperature treatments were conducted in an air atmosphere at 600–1600 °C, and the effects on optical performance (transmittance) and surface morphology were analyzed using ultraviolet–visible–near-infrared spectrophotometry (UV–Vis–NIR) and scanning electron microscopy (SEM). Experimental results reveal that: (1) at temperatures ≤ 600 °C, the average transmittance of SiC in the 350–2000 nm spectral range (below 65%) remains statistically consistent with the as-received substrate; (2) when the temperature rises to 1000 °C, the transmittance in the Vis–NIR region (400–1100 nm) significantly improves by 20%-30%, achieving a peak transmittance of 95%; (3) at 1600 °C, a grayish amorphous silicon–oxygen oxide layer (~ 890 nm thick) forms on the substrate surface, leading to a decline in full-spectrum transmittance and the emergence of characteristic thin-film interference patterns. Mechanical testing demonstrates that the linear thermal expansion coefficient increases at rates of 6 × 10⁻⁹ /°C, respectively, while the elastic modulus decreases at a rate of 0.034 GPa/°C between 600 and 1600 °C. This research provides critical process optimization guidelines for SiC-based high-temperature applications, thermal management for high-power semiconductor devices, and structural design in extreme environments.