@article{5a5a25de2d4e46518afa640597bac42f,
title = "Ultralow-contact-resistance au-free ohmic contacts with low annealing temperature on AlGaN/GaN heterostructures",
abstract = "We report on the electrical and microstructural characterization of Au-free Ti/Al/Ti/TiN contacts for AlGaN/GaN heterostructures. Ultra-low Au-free ohmic contact has been obtained with contact resistance and specific contact resistivity as low as 0.21Ω mm and 1.16 × 10-6 Ω cm2, respectively. The ohmic alloy temperature is reduced as low as 550 °C by pre-ohmic recess of the AlGaN barrier and optimization of the thickness of bottom Ti layer. We found that interfacial layer formation of AlN between the ohmic metal and AlGaN surface is crucial to realize a low contact resistance with reduced low annealing temperature by a combination of electrical I-V characterization and high-resolution transmission electron microscopy analysis. Furthermore, we suggest a hypothesis that the bottom Ti layer plays a catalytic role for the Al-N reaction with optimized thickness.",
author = "Jinhan Zhang and Xuanwu Kang and Xinhua Wang and Sen Huang and Chen Chen and Ke Wei and Yingkui Zheng and Qi Zhou and Wanjun Chen and Bo Zhang and Xinyu Liu",
note = "Funding Information: Manuscript received January 30, 2018; revised March 27, 2018; accepted March 30, 2018. Date of publication April 3, 2018; date of current version May 22, 2018. This work was supported in part by the National Key Research and Development Program of China under Grant 2016YFB0400100 and Grant 2017YFB0403000, in part by the Natural Science Foundation of China under Grant 61474138, Grant 61534007, Grant 11634002, Grant 61334002, Grant 61631021, Grant 61404163, and Grant 61527816, in part by the Key Frontier Project of Chinese Acadamy of Sciences under Grant QYZDB-SSW-JSC012, and in part by the Opening Project of Key Laboratory of Microelectronic Devices and Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences. The review of this letter was arranged by Editor T. Palacios. (Jinhan Zhang and Xuanwu Kang contributed equally to this work.) (Corresponding author: Xuanwu Kang.) J. Zhang, Q. Zhou, W. Chen, and B. Zhang are with the State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China. Publisher Copyright: {\textcopyright} 1980-2012 IEEE.",
year = "2018",
month = jun,
doi = "10.1109/LED.2018.2822659",
language = "English (US)",
volume = "39",
pages = "847--850",
journal = "IEEE Electron Device Letters",
issn = "0741-3106",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "6",
}