Improved device performance in nonpolar a ‐plane GaN LEDs using a Ni/Al/Ni/Au n‐type ohmic contact |
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| Authors: | Dong Ho Kim Su Jin Kim Seung Hwan Kim Tak Jeong Sung Min Hwang Tae Geun Kim |
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| Institution: | 1. School of Electronics and Electrical Engineering, Korea University, 136‐701 Seoul, Korea;2. LED device team, Korea Photonics Technology Institute, 500‐779 Gwangju, Korea;3. Optoelectronics Lab., Korea Electronics Technology Institute, 463‐816 Gyeonggi, Korea |
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| Abstract: | The authors report upon the increased light‐output power (Pout) via a reduction in the forward voltage (Vf) for nonpolar a ‐plane GaN LEDs using Ni/Al/Ni/Au n‐type ohmic contacts. The specific contact resistivity of the Ni/Al/Ni/Au contact is found to be as low as 5.6 × 10–5 whereas that of a typical Ti/Al/Ni/Au contact is 6.8 × 10–4 Ω cm2, after annealing at 700 °C. The X‐ray photoelectron spectroscopy results show that the upward surface band bending is less pronounced for the Ni/Al contact compared to the Ti/Al contact, leading to a decrease in the effective Schottky barrier height (SBH). The Vf of the nonpolar LEDs decreases by 10% and Pout increases by 15% when the Ni/Al/Ni/Au scheme is used instead of the typical Ti/Al/Ni/Au metal scheme. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) |
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| Keywords: | nonpolar GaN LED Ni− Al alloys current injection |
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