Enabling thin p-GaN Ohmic contacts through ultrathin magnesium deposition and brief thermal annealing
Abstract
Gallium nitride (GaN) is a key semiconductor for optoelectronic and power electronic applications. However, achieving low-resistance Ohmic contacts to p-GaN remains challenging, particularly after plasma processing. Annealing of metallic magnesium (Mg) film on p-GaN has emerged as a promising approach, but severe surface roughening limits its applicability to thin (<100 nm) p-GaN layers widely used in practical devices. Here, we demonstrate a capless ultrathin (<10 nm) Mg deposition followed by a soft anneal (600 °C, 300 s) that forms a smooth, ultra-shallow, heavily acceptor-doped surface layer. The process maintains surface smoothness while achieving a low specific contact resistivity of (1–3) × 10−4 Ω cm2 at zero-bias with linear I–V characteristics, even on plasma-etched surfaces. Quasi-vertical p–i–n diodes fabricated using this approach exhibit low leakage currents and high breakdown voltages, indicating preserved junction integrity. This work provides a practical and scalable strategy for forming robust Ohmic contacts on thin p-GaN, with broad implications for GaN-based electronic and optoelectronic devices.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (16)
Haitao Wang
Department of Central Laboratory, College & Hospital of Stomatology, Anhui Provincial Key Laboratory of Oral Diseases Research, Anhui Medical University
Shumeng Yan
Institute of Materials and Systems for Sustainability, Nagoya University 1 , Nagoya 464-8601,
Zhiyu Xu
Yingying Lin
School of Chemistry and Molecular Engineering
Peirong Yu
School of Engineering, Nagoya University 4 , Nagoya 464-8601,
Joshua Jaehyung Park
Microsystems Technology Laboratories, Massachusetts Institute of Technology 6 , Cambridge, Massachusetts 02139,
Joseph E. Dill
School of Applied Engineering Physics, Cornell University 7 , Ithaca, New York 14853,
Hei Wong
Department of Electrical Engineering, City University of Hong Kong 8 , Hong Kong,
Qingyuan Han
Graduate School of Engineering, Nagoya University 9 , Nagoya 464-8601,
Xigen Li
Graduate School of Engineering, Nagoya University 9 , Nagoya 464-8601,
Qian Sun
Tomás Palacios
Debdeep Jena
School of Electrical and Computer Engineering, Cornell University 2 , Ithaca, New York 14853,
Huili Grace Xing
Institute of Materials and Systems for Sustainability, Nagoya University 1 , Nagoya 464-8601,
Jia Wang
Hiroshi Amano
Institute of Materials and Systems for Sustainability, Nagoya University 1 , Nagoya 464-8601,