中国物理B ›› 2021, Vol. 30 ›› Issue (6): 67306-067306.doi: 10.1088/1674-1056/abd6fa

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Electrochemical liftoff of freestanding GaN by a thick highly conductive sacrificial layer grown by HVPE

Xiao Wang(王骁)1,2,3, Yu-Min Zhang(张育民)3,4, Yu Xu(徐俞)3,4, Zhi-Wei Si(司志伟)3, Ke Xu(徐科)3,4, Jian-Feng Wang(王建峰)3,4,†, and Bing Cao(曹冰)1,2,‡   

  1. 1 School of Optoelectronic Science and Engineering, Soochow University, Suzhou 215006, China;
    2 Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Laboratory of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China;
    3 Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO), Chinese Academy of Sciences(CAS), Suzhou 215123, China;
    4 Suzhou Nanowin Science and Technology Co., Ltd, Suzhou 215123, China
  • 收稿日期:2020-11-15 修回日期:2020-12-11 接受日期:2020-12-28 出版日期:2021-05-18 发布日期:2021-05-27
  • 通讯作者: Jian-Feng Wang, Bing Cao E-mail:jfwang2006@sinano.ac.cn;bcao2006@163.com
  • 基金资助:
    Project supported by the National Key R&D Program of China (Grant Nos. 2017YFB0404100 and 2017YFB0403000), the National Natural Science Foundation of China (Grant No. 61704187), and the Key Research Program of the Frontier Science of the Chinese Academy of Sciences (Grant No. QYZDB-SSW-SLH042).

Electrochemical liftoff of freestanding GaN by a thick highly conductive sacrificial layer grown by HVPE

Xiao Wang(王骁)1,2,3, Yu-Min Zhang(张育民)3,4, Yu Xu(徐俞)3,4, Zhi-Wei Si(司志伟)3, Ke Xu(徐科)3,4, Jian-Feng Wang(王建峰)3,4,†, and Bing Cao(曹冰)1,2,‡   

  1. 1 School of Optoelectronic Science and Engineering, Soochow University, Suzhou 215006, China;
    2 Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Laboratory of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China;
    3 Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO), Chinese Academy of Sciences(CAS), Suzhou 215123, China;
    4 Suzhou Nanowin Science and Technology Co., Ltd, Suzhou 215123, China
  • Received:2020-11-15 Revised:2020-12-11 Accepted:2020-12-28 Online:2021-05-18 Published:2021-05-27
  • Contact: Jian-Feng Wang, Bing Cao E-mail:jfwang2006@sinano.ac.cn;bcao2006@163.com
  • Supported by:
    Project supported by the National Key R&D Program of China (Grant Nos. 2017YFB0404100 and 2017YFB0403000), the National Natural Science Foundation of China (Grant No. 61704187), and the Key Research Program of the Frontier Science of the Chinese Academy of Sciences (Grant No. QYZDB-SSW-SLH042).

摘要: Separation technology is an indispensable step in the preparation of freestanding GaN substrate. In this paper, a large-area freestanding GaN layer was separated from the substrate by an electrochemical liftoff process on a sandwich structure composed of an Fe-doped GaN substrate, a highly conductive Si-doped sacrificial layer and a top Fe-doped layer grown by hydride vapor phase epitaxy (HVPE). The large difference between the resistivity in the Si-doped layer and Fe-doped layer resulted in a sharp interface between the etched and unetched layer. It was found that the etching rate increased linearly with the applied voltage, while it continuously decreased with the electrochemical etching process as a result of the mass transport limitation. Flaky GaN pieces and nitrogen gas generated from the sacrificial layer by electrochemical etching were recognized as the main factors responsible for the blocking of the etching channel. Hence, a thick Si-doped layer grown by HVPE was used as the sacrificial layer to alleviate this problem. Moreover, high temperature and ultrasonic oscillation were also found to increase the etching rate. Based on the results above, we succeeded in the liftoff of ~1.5 inch GaN layer. This work could help reduce the cost of freestanding GaN substrate and identifies a new way for mass production.

关键词: electrochemical etching, liftoff, hydride vapor phase epitaxy (HVPE), freestanding GaN

Abstract: Separation technology is an indispensable step in the preparation of freestanding GaN substrate. In this paper, a large-area freestanding GaN layer was separated from the substrate by an electrochemical liftoff process on a sandwich structure composed of an Fe-doped GaN substrate, a highly conductive Si-doped sacrificial layer and a top Fe-doped layer grown by hydride vapor phase epitaxy (HVPE). The large difference between the resistivity in the Si-doped layer and Fe-doped layer resulted in a sharp interface between the etched and unetched layer. It was found that the etching rate increased linearly with the applied voltage, while it continuously decreased with the electrochemical etching process as a result of the mass transport limitation. Flaky GaN pieces and nitrogen gas generated from the sacrificial layer by electrochemical etching were recognized as the main factors responsible for the blocking of the etching channel. Hence, a thick Si-doped layer grown by HVPE was used as the sacrificial layer to alleviate this problem. Moreover, high temperature and ultrasonic oscillation were also found to increase the etching rate. Based on the results above, we succeeded in the liftoff of ~1.5 inch GaN layer. This work could help reduce the cost of freestanding GaN substrate and identifies a new way for mass production.

Key words: electrochemical etching, liftoff, hydride vapor phase epitaxy (HVPE), freestanding GaN

中图分类号:  (III-V semiconductors)

  • 73.61.Ey
81.40.Wx (Radiation treatment) 61.72.U- (Doping and impurity implantation)