Dislocation of Cz-sapphire substrate for GaN growth by chemical etching method
The diameter of Czochralski (Cz) sapphire crystals is 50 mm. The sapphire substrates were lapped by using diamond powders and polished by chemical mechanical polishing(CMP) method using alkali slurry with SiO2 abrasive. After obtaining the smooth surfaces,the chemical etching experiments were processed by using fused KOH and NaOH etchants at different temperature for different times. The dislocation was observed by means of optical microscope and scanning electron microscope. The clear and stable contrast images of sample etching pits were observed. On the whole,the dislocation density is about 104-105 cm-2. Comparing the results under the conditions of different etchants,temperatures and times during the etching proceeding,it was found that the optimal condition for dislocation displaying is etching 15 min with fused KOH at 290 ℃. At the same time,the formation of the etch pits and the reducing method of dislocation density were also discussed.
Author: NIU Xin-huan LU Guo-qi ZHANG Wei-lian GAO Jin-yong LIU Yu-ling
作者单位: School of Information Engineering, Hebei University of Technology, Tianjin 300130, China School of Materials, Hebei University of Technology, Tianjin 300130, China
年,卷(期): 2006, 16(z1)
分类号: TG1
机标分类号: O4 TG3
在线出版日期: 2007年8月20日
基金项目: 国家自然科学基金,河北省自然科学基金,高等学校博士学科点专项科研项目