欧姆接触
材料科学
异质结
接触电阻
光电子学
退火(玻璃)
电阻率和电导率
透射电子显微镜
热离子发射
锡
宽禁带半导体
氮化镓
氮化物
图层(电子)
冶金
复合材料
纳米技术
电子
电气工程
物理
量子力学
工程类
作者
Hanghai Du,Zhihong Liu,Lu Hao,Weichuan Xing,Weihang Zhang,Hong Zhou,Jincheng Zhang,Yue Hao
摘要
A low ohmic contact resistance (Rc) is a challenge for an AlGaN/GaN heterostructure with a high Al-composition barrier, which is highly desired to further push the performance of GaN transistors. In this Letter, an effective ohmic contact technique with an in situ SiNx layer inserted between the conventional Ti/Al/Ni/Au metal stack and the III-nitride was proposed and the inside physical mechanisms were investigated for an Al0.65Ga0.35N/GaN heterostructure. The fabricated ohmic contact has a low Rc of 0.17 Ω·mm and a specific contact resistivity value (ρc) of 8.45 × 10−7 Ω·cm2, which is obviously improved compared with the Rc of 0.32 Ω·mm and ρc of 2.84 × 10−6 Ω·cm2 without in situ SiNx inserted. The strong temperature dependency of ρc with in situ SiNx insertion shows that the dominant current transport mechanism is the thermionic field emission. Transmission electron microscopy and energy dispersive x-ray spectroscopy analyses suggest that the enhanced ohmic contact is due to the possible formation of low-work function silicides and more TiN alloys during annealing.
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