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Investigation of Ni/Ag contact to p‐GaN with an O 2 plasma treatment and its application to GaN‐based LEDs
Author(s) -
Lin NanMing,
Shei ShihChang,
Chang ShoouJinn
Publication year - 2012
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201127588
Subject(s) - materials science , contact resistance , light emitting diode , x ray photoelectron spectroscopy , thermionic emission , schottky barrier , plasma , optoelectronics , schottky diode , diode , contact angle , gallium nitride , wide bandgap semiconductor , analytical chemistry (journal) , nanotechnology , chemistry , composite material , electron , nuclear magnetic resonance , physics , layer (electronics) , quantum mechanics , chromatography
In this paper, the contact structure of Ni–Ag/p‐GaN with different O 2 plasma treatment times for 1 and 5 min was utilized for investigation. From experimental results, the Ni–Ag contact to p‐GaN with different O 2 plasma treatment for 1 and 5 min reveals Schottky behaviors. Based on the variation of the specific contact resistance with respect to temperature, the dominant transport mechanism of Ni–Ag/p‐GaN structure presented form thermionic emission to field emission as increasing time from 1 to 5 min. From the X‐ray photoelectron spectroscopy (XPS) results, the increase of the N vacancies and antisite defects (O N ) would enhance the resistance of the treated p‐GaN underneath the contact, which would make the Ni–Ag/p‐GaN contact reveal Schottky behavior. With a 20 mA current injection, the operation voltage of light‐emitting diodes (LEDs) with Ni/Ag contact to p‐GaN through O 2 plasma treatment 400 W–5 min was 3.13 V larger than the LEDs with Ni/Ag contact to p‐GaN through O 2 plasma treatment 400 W–1 min. This is due to the larger specific contact resistance. The 3.13 V operation voltage is still good and acceptable. Furthermore, the largest output power among all devices can be achieved. Besides, the reliability is still good.