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Direct Observation of High Current Density Area by Microscopic Electroluminescence Mapping in Vertical GaN p–n Junction Diodes
Author(s) -
Hayashi Kentaro,
Ohta Hiroshi,
Horikiri Fumimasa,
Narita Yoshinobu,
Yoshida Takehiro,
Mishima Tomoyoshi
Publication year - 2018
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.201700501
Subject(s) - current crowding , electroluminescence , materials science , diode , optoelectronics , flatness (cosmology) , current density , doping , epitaxy , light emitting diode , current (fluid) , layer (electronics) , nanotechnology , electrical engineering , physics , cosmology , quantum mechanics , engineering
This paper presents electroluminescence intensity mapping on a p–n junction plane of vertical GaN diodes under forward‐biased conditions for the first time. By this mapping, it has been discovered that current crowding existed, corresponding to the naturally formed surface stripes on epitaxial layers grown on freestanding GaN substrates. Detailed analyses by AFM and TOF‐SIMS clarified that the concentration of doped Mg acceptors on one slope of the stripe was higher than that on the other slope. The higher Mg‐concentration region should have lower electric resistance, which would cause the current crowding. By improving the surface flatness, the current crowding was suppressed and a low specific on‐resistance was obtained.