正晶向SiC衬底上表面光滑的N极性GaN薄膜材料的生长  

Growth of Smooth N‑polar GaN Films on On‑axis SiC Substrates

作　　者：沈睿 李传皓[1] 李忠辉[1] 彭大青[1] 张东国[1] 杨乾坤[1] 罗伟科[1] SHEN Rui;LI Chuanhao;LI Zhonghui;PENG Daqing;ZHANG Dongguo;YANG Qiankun;LUO Weike(Science and Technology on Monolithic Integrated Circuits and Modules Laboratory,Nanjing Electronic Devices Institute,Nanjing,210016,CHN)

机构地区：[1]南京电子器件研究所,微波毫米波单片集成电路与模块技术重点实验室,南京210016

出　　处：《固体电子学研究与进展》2022年第2期150-156,共7页Research & Progress of SSE

基　　金：江苏省重点研发计划(SBE2020020137)。

摘　　要：采用MOCVD技术在101.6 mm(4英寸)正晶向半绝缘C面SiC衬底上生长了厚度为1μm的GaN缓冲层。通过深入研究不同AlN成核层上生长的GaN缓冲层的性质,揭示了正晶向SiC衬底上氮极性GaN的生长机制,发现成核层表面AlN岛的密度是决定缓冲层表面形貌的重要参数,对后续GaN的成核以及GaN岛间的合并具有显著影响。通过在AlN成核层外延期间引入N2作为载气并且以脉冲方式供应铝源,研制的成核层表面成核岛尺寸小且致密性高,有利于促进GaN成核岛之间的横向合并,并抑制GaN缓冲层的岛状生长模式,从而获得了表面光滑的N极性GaN薄膜材料,原子力显微镜20μm×20μm扫描范围下的均方根(rms)粗糙度值为1.5 nm。此外,在表面平滑的GaN薄膜上生长的GaN/AlGaN异质结的电子输运特性也同步得到提升,这有利于N极性GaN材料的微波应用。N-polar GaN buffer layer(BL)with thickness of 1μm was grown on 101.6 mm(4-inch)on-axis semi-insulating C-face 4H-SiC substrate by MOCVD in this article.Through a detailed insight into the properties of GaN BLs overgrown on various AlN NLs,the growth mechanism of Npolar GaN on on-axis SiC substrate was revealed.It is found that the density of AlN islands on AlN nucleation layer(NL)has an obvious impact on the GaN nuclei and the coalescence of GaN islands,which is the crucial parameter determining the surface morphology of GaN BL.As interval supply of Al precursor with carrier gas of nitrogen is introduced into NL growth procedure,high density of AlN islands with small spacings are exhibited on the NL surface,which prompts lateral coalescence of GaN islands and restrains island-growth mode of GaN BL,achieving quite a smooth surface of GaN BL with root mean square roughness value of 1.5 nm in a 20μm×20μm area.In addition,GaN/Al‑GaN heterostructures upon the smooth GaN BL possess ameliorative electron transport characteristics,beneficially to practical N-polar GaN microwave applications.

关 键 词：N极性GaN MOCVD AlN成核层 正晶向SiC衬底 微波应用 

分 类 号：O781[理学—晶体学] O782