彭观良
,
邹军
,
庄漪
,
张涟翰
,
周国清
,
周圣明
,
徐军
,
干福熹
人工晶体学报
doi:10.3969/j.issn.1000-985X.2005.02.018
由于与GaN晶格失配小(约1.4%),γ-LiAlO2单晶有望成为一种很有希望的CaN外延衬底材料.本文使用提拉法生长出了尺寸达φ45×50mm3的γ-LiAlO2单晶.对该晶体毛坯的各个有代表性的位置作了X射线粉末衍射(XRPD)分析,结果表明仅仅在晶体毛坯的底部生成了一种缺锂相(LiAl5O8).γ-LiAlO2晶体化学稳定性差,在室温时轻微水解.当在空气中于1100℃退火70h,γ-LiAlO2晶体挥发出锂组分,在表面产生缺锂相(LiAl5O8).值得注意的是,在γ-LiAlO2晶体的红外光谱区不存在氢氧根吸收带.
关键词:
晶体生长
,
提拉法
,
γ-LiAlO2
,
外延
,
GaN
,
衬底
,
红外
Jun ZOU
材料科学技术（英）
Large-sized (~2 inch, 50.8 mm) γ-LiAlO2 single crystal has been grown by conventional Czochralski (Cz) method, but the crystal has a milky, dendriform center. The samples taken from transparent and milky parts were ground and examined by X-ray diffraction. All diffraction peaks could be indexed in γ-LiAlO2. The crystal quality was characterized by X-ray rocking curve. The full-width at half-maximum (FWHM) values are 116.9 and 132.0~arcsec for transparent and milky parts, respectively. The vapor transport equilibrium (VTE) technique was introduced to modify the crystal quality. After 1000℃/48 h, 1100℃/48 h, 1200℃/48 h VTE processes, the FWHM values dropped to 44.2 and 55.2 arcsec for transparent and milky part, respectively. The optical transmission of transparent part was greatly enhanced from 85% to 90%, and transmission of milky part from 75% to 80% in the range of 190~1900 nm at room temperature. When the VTE temperature was raised to 1300℃, the sample cracked and FWHM values of transparent and milky parts were increased to 55.2 and 80.9 arcsec, respectively. By combining Cz technique with VTE technique, large-sized and high quality γ-LiAlO2 crystal can be obtained.
关键词:
γ-LiAlO2 crystal
,
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,
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