Low resistance copper-based ohmic contact for AlGaN/GaN high electron mobility transistors

作者：Wong Yuen Yee; Chen Yu Kong; Maa Jer Shen; Yu Hung Wei; Tu Yung Yi; Dee Chang Fu; Yap Chi Chin; Chang Edward Yi^*

来源：Applied Physics Letters, 2013, 103(15): 152104.

DOI：10.1063/1.4824894

Ti/Al/Ni/Cu ohmic contact for AlGaN/GaN structure has been fabricated. The Ni layer played an important role in achieving low specific contact resistance (r(c)), smooth morphology, and excellent edge acuity. With a 50-angstrom Ni layer, a r(c) of 1.35 x 10(-6) Omega-cm(2) and a root-mean-square roughness of 7.65 nm have been realized. The characterization results indicated that no evidence of Cu diffusion into the semiconductor layers. The formation of Al-Cu and Ti-Cu alloys might have confined the Cu within the ohmic metal. In the absence of gold, the surface roughening caused by Au-Al alloy in conventional Ti/Al/Ni/Au structure was also prevented.

• 出版日期2013-10-7