Optical property in colorless AlN bulk crystals: investigation of native defect-induced UV absorption

The 4.7 eV absorption band of colorless AlN crystal with the carbon concentration level of 10(7) cm(-3) is investigated. An analysis of the absorption characteristics of the annealed AlN crystal indicates that the native defect is the origin of 4.7 eV absorption band and gives rise to an infrared absorption band at 2850 cm(-1). The theory calculations predict two absorption bands at 4.65 eV and 0.35 eV of nitrogen vacancy, and the defect explains the increased and decreased intensity of infrared absorption band at 2850 cm(-1) as well as a similar increased-decreased ultraviolet absorption band at 4.7 eV. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study revealed that the native defect in colorless AlN crystal is the origin of the 4.7 eV absorption band, leading to an infrared absorption band at 2850 cm(-1). Theoretical calculations predicted two absorption bands of nitrogen vacancy at 4.65 eV and 0.35 eV, explaining the characteristics of the infrared absorption band at 2850 cm(-1) and the 4.7 eV ultraviolet absorption band.