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Improved device performance in nonpolar a ‐plane GaN LEDs using a Ni/Al/Ni/Au n‐type ohmic contact
Author(s) -
Kim Dong Ho,
Kim Su Jin,
Kim Seung Hwan,
Jeong Tak,
Hwang Sung Min,
Kim Tae Geun
Publication year - 2011
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201105265
Subject(s) - ohmic contact , light emitting diode , materials science , annealing (glass) , schottky barrier , band bending , x ray photoelectron spectroscopy , optoelectronics , electrical resistivity and conductivity , metal , contact resistance , contact angle , diode , analytical chemistry (journal) , metallurgy , chemistry , composite material , electrical engineering , chemical engineering , layer (electronics) , chromatography , engineering
The authors report upon the increased light‐output power ( P out ) via a reduction in the forward voltage ( V f ) 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 cm 2 , 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 V f of the nonpolar LEDs decreases by 10% and P out 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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