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Performance Improvement of GaN Based Laser Diode Using Pd/Ni/Au Metallization Ohmic Contact

1,2,*, 1,2, 1,2, 1,2, 1,2, 1,2, 1,2, 1,2,* and 3,4
Microsystem & Terahertz Research Center, China Academy of Engineering Physics, Chengdu 610200, China
Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621999, China
State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083, China
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
Authors to whom correspondence should be addressed.
Coatings 2019, 9(5), 291;
Received: 30 March 2019 / Revised: 21 April 2019 / Accepted: 25 April 2019 / Published: 28 April 2019
(This article belongs to the Special Issue Advanced Coating Materials for Power Network Equipment)
PDF [3362 KB, uploaded 28 April 2019]


We report an investigation of the effects of different metal systems and surface treatment on the contact performance of GaN lasers. We found that multi-element metal alloy and surface chemical treatment are the keys to achieve good ohmic behavior contacts on GaN laser diodes. Pd/Ni/Au contact demonstrates excellent thermal stability and lowest specific contact resistivity in these metal systems. Properly adjusting the thickness of the Pd and Ni layer and pretreating with the KOH solution can further improve the ohmic contact performance. The improved ohmic behavior of the KOH solution pretreated Pd/Ni/Au contact is attributed to removing surface oxides and the reduction of the schottky barrier heights due to the metal Pd has a high work function and the interfacial reactions occurring between the Pd, Ni, Au, and GaN extends into the GaN film. As a result, a low contact resistivity of 1.66 × 10−5 Ω·cm2 can be achieved from Pd(10 nm)/Ni(10 nm)/Au(30 nm) contacts with KOH solution pretreated on top of the laser diode structure. The power of the GaN based laser diode with the Pd/Ni/Au metallization ohmic contact can be enhanced by 1.95 times and the threshold current decreased by 37% compared to that of the conventional ohmic contact Ni/Au. View Full-Text
Keywords: GaN; laser diode; ohmic contact; PVD deposition; alloys; Pd/Ni/Au GaN; laser diode; ohmic contact; PVD deposition; alloys; Pd/Ni/Au

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Wang, W.; Xie, W.; Deng, Z.; Yang, H.; Liao, M.; Li, J.; Luo, X.; Sun, S.; Zhao, D. Performance Improvement of GaN Based Laser Diode Using Pd/Ni/Au Metallization Ohmic Contact. Coatings 2019, 9, 291.

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