Improved Ohmic contact to GaN and AlGaN/GaN two-dimensional electron gas using trap assisted tunneling by B implantation

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...

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Bibliographic Details
Published in:Physica Status Solidi. B: Basic Solid State Physics 2015-05, Vol.252 (5), p.989-995
Main Authors: Upadhyay, Pankaj, Meer, Mudassar, Takhar, Kuldeep, Khachariya, Dolar, Kumar S, Akhil, Banerjee, Debashree, Ganguly, Swaroop, Laha, Apurba, Saha, Dipankar
Format: Article
Language:English
Subjects:
Aluminum gallium nitrides
Contact resistance
Electrical resistivity
Electron gas
Gallium nitrides
GaN
high electron mobility transistors
Implantation
Ion implantation
Ohmic contacts
trap assisted tunneling
Tunneling
two-dimensional electron gas
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Summary: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.
ISSN:0370-1972
1521-3951
DOI:10.1002/pssb.201451586