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Improved Ohmic contact to GaN and AlGaN/GaN two‐dimensional electron gas using trap assisted tunneling by B implantation
Author(s) -
Upadhyay Pankaj,
Meer Mudassar,
Takhar Kuldeep,
Khachariya Dolar,
Kumar S Akhil,
Banerjee Debashree,
Ganguly Swaroop,
Laha Apurba,
Saha Dipankar
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201451586
Subject(s) - ohmic contact , contact resistance , materials science , heterojunction , optoelectronics , quantum tunnelling , annealing (glass) , penning trap , ion implantation , fermi gas , electron , condensed matter physics , ion , nanotechnology , layer (electronics) , chemistry , composite material , physics , organic chemistry , quantum mechanics
We have demonstrated that deep level traps created by B implantation can reduce the contact resistance by forming an additional path for electron transport via trap assisted tunneling in GaN and AlGaN/GaN heterostructures. B implantation by plasma‐immersion ion implantation creates deep level traps 0.36 eV below the conduction band edge to a shallow depth (10–25 nm) in the structure. These traps act as efficient percolation path for electrons between the TiN Ohmic contact and the active region, which can be bulk GaN or a two‐dimensional electron gas (2DEG) formed at the AlGaN/GaN heterostructure. The improved Ohmic behavior is manifested as reduced specific contact resistivity and normalized contact resistance. The specific contact resistance and the normalized contact resistance are found to decrease by 59% (30%) and 86% (51%), respectively, for bulk GaN (AlGaN/GaN). The effect of B implantation on the sheet resistance of the 2DEG is insignificant when the implantation energy and post‐implantation annealing time are controlled optimally.