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<p>AlN crystals are considered promising candidates for high-power electronic and deep-ultraviolet optoelectronic applications, owing to their ultra-wide bandgap, high critical breakdown electric field, excellent thermal conductivity, and favorable ultraviolet transparency. However, the introduction of internal impuritiescan substantially alter the intrinsic physical properties of the crystal, thereby limiting device performance. In this study, AlN single-crystal samples were grown by physical vapor transport (PVT) under different thermal insulation schemes, followed by systematic investigations of their impurity concentrations and optical properties. The results indicate that employing a tungsten-molybdenum thermal insulation system can significantly reduce the concentrations of C, O, and Si impurities in AlN crystals. Further investigations reveal an intrinsic correlation between the optical absorption properties of AlN crystals and impurity concentrations. A red shift of the absorption cutoff edge is observed, accompanied by pronounced absorption bands at approximately 1.8&#xa0;eV, 2.8&#xa0;eV, and 4.7&#xa0;eV, which are attributed to the presence of C and O impurities. Furthermore, the correlation between the intensities of the observed absorption bands and the concentrations of C, O, and Si impurities is systematically investigated, providing insight into the controlled growth of high-purity AlN single crystals.</p>

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Effects of different growth systems on impurity characteristics in AlN crystals

  • 期刊论文

  • 发表日期：

    2026年5月4日

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  • Ruixian Yu,
  • Gang Zhao,
  • Wenjing Tang,
  • Kai Jiang,
  • Lei Zhang,
  • Wei Xia

摘要

AlN crystals are considered promising candidates for high-power electronic and deep-ultraviolet optoelectronic applications, owing to their ultra-wide bandgap, high critical breakdown electric field, excellent thermal conductivity, and favorable ultraviolet transparency. However, the introduction of internal impuritiescan substantially alter the intrinsic physical properties of the crystal, thereby limiting device performance. In this study, AlN single-crystal samples were grown by physical vapor transport (PVT) under different thermal insulation schemes, followed by systematic investigations of their impurity concentrations and optical properties. The results indicate that employing a tungsten-molybdenum thermal insulation system can significantly reduce the concentrations of C, O, and Si impurities in AlN crystals. Further investigations reveal an intrinsic correlation between the optical absorption properties of AlN crystals and impurity concentrations. A red shift of the absorption cutoff edge is observed, accompanied by pronounced absorption bands at approximately 1.8 eV, 2.8 eV, and 4.7 eV, which are attributed to the presence of C and O impurities. Furthermore, the correlation between the intensities of the observed absorption bands and the concentrations of C, O, and Si impurities is systematically investigated, providing insight into the controlled growth of high-purity AlN single crystals.