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Characterization of Freestanding AlN Single Crystals Growth through a Novel Approach Using the PVT Method
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School of Materials Science and Engineering, Shanghai University

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    Abstract:

    In this paper, a novel approach to grow freestanding AlN single crystals spontaneously using the physical vapor transport method is presented. Dozens of single crystals can be obtained on the surface of a pre-sintered AlN powder source in a single growth run using this approach. In this study, the largest AlN single crystal for 100 h of growth at 2373–2523 K was 7 × 8 × 12 mm3, and the typical diameter was 5–7 mm. The surface morphologies of the as-grown crystals were investigated by scanning electron microscopy, whereas the structural quality of the crystals was characterized by Raman spectroscopy and high-resolution X-ray diffraction. Raman spectroscopy exhibited an E2 (high) full width at half maximum (FWHM) of 5.7 cm-1, whereas the high-resolution X-ray diffraction rocking curve showed a FWHM of 93.6 arcsec for the symmetric reflection. The average etch pit density revealed by preferential chemical etching was 7.5 × 104 cm-2, and the major impurities determined by evolved gas analysis and glow discharge mass spectrometry were carbon at 28 ppmw and oxygen at 120 ppmw. The proposed novel approach provides a new means of obtaining high-quality AlN single crystals, which can be cut into wafers and are ideal as seeds for subsequent homoepitaxial AlN growth. Using these small seeds, crack-free bulk AlN single crystal/wafers that have excellent deep UV transparency and are up to 60 mm in diameter were successfully prepared for the first time.

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[wzh, wuliang. Characterization of Freestanding AlN Single Crystals Growth through a Novel Approach Using the PVT Method[J]. Rare Metal Materials and Engineering,2020,49(10):3337~3352.]
DOI:10.12442/j. issn.1002-185X.20190708

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History
  • Received:August 28,2019
  • Revised:November 11,2019
  • Adopted:November 12,2019
  • Online: November 04,2020
  • Published: