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

作　　者：Xiao Wang Yu-Min Zhang Yu Xu Zhi-Wei Si Ke Xu Jian-Feng Wang Bing Cao 王骁;张育民;徐俞;司志伟;徐科;王建峰;曹冰(School of Optoelectronic Science and Engineering,Soochow University,Suzhou 215006,China;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;Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO),Chinese Academy of Sciences(CAS),Suzhou 215123,China;Suzhou Nanowin Science and Technology Co.,Ltd,Suzhou 215123,China)

机构地区：[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

出　　处：《Chinese Physics B》2021年第6期531-535,共5页中国物理B（英文版）

基　　金：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);the Key Research Program of the Frontier Science of the Chinese Academy of Sciences (Grant No. QYZDB-SSWSLH042)。

摘　　要：Separation technology is an indispensable step in the preparation of freestanding GaN substrate. In this paper, a largearea 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 

分 类 号：TN304[电子电信—物理电子学]