Rapid silicon outdiffusion from SiC substrates during molecular-beam epitaxial growth of AlGaN∕GaN∕AlN transistor structures
Rapid silicon outdiffusion from SiC substrates during molecular-beam epitaxial growth of AlGaN∕GaN∕AlN transistor structures
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AlGaN∕GaN∕AlN 晶体管结构分子束外延生长过程中硅从 SiC 衬底快速向外扩散
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
T. Kennedy
中科院分区：
文献类型：
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作者：
W. Hoke;A. Torabi;J. Mosca;R. Hallock;T. Kennedy
采用分子束外延技术在碳化硅衬底上生长了AlGaN/GaN/AlN晶体管结构。在富铝的AlN成核层生长条件下，对于更厚的(>；1000A)AlN层，在GaN/AlN界面附近观察到不理想的n型导电。通过二次离子质谱仪测量，硅被确定为不需要的掺杂剂。原子力显微镜表面图显示在适度富铝条件下生长的AlN表面上有游离的铝金属。认为硅的快速迁移是由于铝熔体与碳化硅衬底发生反应，导致溶解的硅通过生长的AlN层快速迁移所致。当铝与活性氮的生长流量比接近1时，这一行为显著减少。由此产生的GaN高电子迁移率晶体管结构的缓冲器漏电流降低了四个数量级以上。
AlGaN∕GaN∕AlN transistor structures were grown onto SiC substrates by molecular-beam epitaxy. Under aluminum-rich growth conditions for the AlN nucleation layer, undesirable n-type conduction is observed near the GaN∕AlN interface for even thick (>1000A) AlN layers. Silicon is identified as the unwanted dopant from secondary-ion mass spectroscopy measurements. Atomic force microscopy surface maps reveal free aluminum metal on AlN surfaces grown under modest aluminum-rich conditions. It is proposed that rapid silicon migration is caused by molten aluminum reacting with the SiC substrate resulting in dissolved silicon that rapidly migrates through the growing AlN layer. This behavior is significantly reduced using a growth flux ratio of aluminum to reactive nitrogen close to unity. The resulting buffer leakage current of the GaN high electron mobility transistor structure is reduced by more than four orders of magnitude.