人工晶体学报, 2020, 49 (7): 1162, 网络出版: 2020-08-18  

PVT法钨坩埚系统中自发生长自支撑AlN单晶及其表征分析

Growth and Characterization of Freestanding AlN by PVT Method under Tungsten Crucible System
作者单位
上海大学材料科学与工程学院,省部共建高品质特殊钢冶金与制备国家重点实验室,上海市钢铁冶金新技术开发应用重点实验室,上海 200444
摘要
采用物理气相传输(PVT)法在AlN原料表面自发生长出大量毫米级尺寸的AlN单晶。本文对该工艺下AlN单晶的自然形貌、极性、杂质含量等进行了分析。实验及分析结果表明,在实验工艺条件下,原料表面生长的AlN晶粒具有规则的六方外形,晶粒沿C向择优生长且具有高的生长速率(约200~250 μm/h),但径向生长受限于{10-10}(m面)。不同颜色的AlN晶粒经机械切割及化学机械抛光(CMP)后,形成高表面质量的C轴取向抛光片。通过化学湿法腐蚀和SEM表征发现,淡黄色晶粒为Al极性晶体,暗棕色晶粒为N极性晶体,淡黄-暗棕混合色晶粒为Al/N混合极性晶体,其内部可以观察到清晰的两种极性分界。通过GDMS与EGA对不同颜色晶粒内部的主要杂质元素含量进行了分析,结果表明,淡黄色晶粒内氧元素的含量相比暗棕色晶粒的含量低,而碳含量则相反。
Abstract
Donzens of millimeter-sized freestanding AlN single crystals were grown on the surface of a pre-sintered AlN powder source by the physical vapor transfer (PVT) method. In this paper, the natural growth habits, polarity, and impurity content of the obtained AlN single crystals by this novel approach were analyzed. The results show that the AlN single crystals grown on the surface of pre-sintered AlN powder source have a regular hexagonal shape. The preferential growth direction is along [0001] or C-direction with growth rate of 200-250 μm/h, while the radial growth is limited by {10-10} (m-plane). AlN crystals with different colors were sliced into C-axis wafers and then lapped/polished by chemical and mechanical polishing process. The obtained wafers were characterized by selective-wet-etching, and the SEM results reveal that light yellow crystals are Al-polar growth and the dark brown crystals are N-polar growth, while light yellow-dark brown crystals are Al/N mixed polar growth and clear boundaries can be observed between two polarities. Glow discharge mass spectrometry (GDMS) and evolved gas analysis(EGA) were employed to analyze the main impurities in the crystals with different colors. The results show that the content of oxygen in the light yellow crystals is lower than that of the dark brown crystals, while the carbon content is opposite in these crystals with different colors.

龚建超, 朱如忠, 刘欢, 王琦琨, 李哲, 张刚, 吴亮. PVT法钨坩埚系统中自发生长自支撑AlN单晶及其表征分析[J]. 人工晶体学报, 2020, 49(7): 1162. GONG Jianchao, ZHU Ruzhong, LIU Huan, WANG Qikun, LI Zhe, ZHANG Gang, WU Liang. Growth and Characterization of Freestanding AlN by PVT Method under Tungsten Crucible System[J]. Journal of Synthetic Crystals, 2020, 49(7): 1162.

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