Extreme sensitivity of contact resistance to variations in the interfacial composition of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures

Michael Abraham; Xiaojun Weng; Won Hyuck Choi; Brian P. Downey; Suzanne E. Mohney

doi:10.1063/1.4770365

Extreme sensitivity of contact resistance to variations in the interfacial composition of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures

Michael Abraham, Xiaojun Weng, Won Hyuck Choi, Brian P. Downey, Suzanne E. Mohney

Research output: Contribution to journal › Article › peer-review

Abstract

The resistance of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures was found to depend sensitively on their interfacial composition. Limiting the thickness of the first layer deposited (either Al or Ti) to a few nanometers resulted in low contact resistances after annealing for 1min at 500°C. The lowest contact resistance of 0.10 Ω mm (contact resistivity of 3×10^-7 Ω cm²) was achieved with 3nm of Al as the first deposited layer. Transmission electron microscopy revealed a thin Ti-Al-Ga-N layer adjacent to the GaN in this annealed Al/Ti/Al contact, while the contact resistance was higher when the interfacial layer contained only Ti, Ga, and N. The simultaneous presence of Al and Ti next to GaN at the onset of reaction was found to be critical for achieving the lowest contact resistance.

Original language	English (US)
Article number	243504
Journal	Applied Physics Letters
Volume	101
Issue number	24
DOIs	https://doi.org/10.1063/1.4770365
State	Published - Dec 10 2012

All Science Journal Classification (ASJC) codes

Physics and Astronomy (miscellaneous)

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10.1063/1.4770365

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@article{ff31bdeabdc440c3b6a70d28eaafd01d,

title = "Extreme sensitivity of contact resistance to variations in the interfacial composition of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures",

abstract = "The resistance of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures was found to depend sensitively on their interfacial composition. Limiting the thickness of the first layer deposited (either Al or Ti) to a few nanometers resulted in low contact resistances after annealing for 1min at 500°C. The lowest contact resistance of 0.10 Ω mm (contact resistivity of 3×10-7 Ω cm2) was achieved with 3nm of Al as the first deposited layer. Transmission electron microscopy revealed a thin Ti-Al-Ga-N layer adjacent to the GaN in this annealed Al/Ti/Al contact, while the contact resistance was higher when the interfacial layer contained only Ti, Ga, and N. The simultaneous presence of Al and Ti next to GaN at the onset of reaction was found to be critical for achieving the lowest contact resistance.",

author = "Michael Abraham and Xiaojun Weng and {Hyuck Choi}, Won and Downey, {Brian P.} and Mohney, {Suzanne E.}",

note = "Funding Information: The authors are grateful to DARPA for support through the NeXt program (Dr. John Albrecht), to Northrop Grumman Corporation for providing nitride epilayers for this work, and to the NSF National Nanotechnology Infrastructure Network (ECCS-0335765) for access to its nanofabrication facilities. Michael Abraham also received support as a Gates Millennium Scholar.",

year = "2012",

month = dec,

day = "10",

doi = "10.1063/1.4770365",

language = "English (US)",

volume = "101",

journal = "Applied Physics Letters",

issn = "0003-6951",

publisher = "American Institute of Physics",

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T1 - Extreme sensitivity of contact resistance to variations in the interfacial composition of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures

AU - Abraham, Michael

AU - Weng, Xiaojun

AU - Hyuck Choi, Won

AU - Downey, Brian P.

AU - Mohney, Suzanne E.

N1 - Funding Information: The authors are grateful to DARPA for support through the NeXt program (Dr. John Albrecht), to Northrop Grumman Corporation for providing nitride epilayers for this work, and to the NSF National Nanotechnology Infrastructure Network (ECCS-0335765) for access to its nanofabrication facilities. Michael Abraham also received support as a Gates Millennium Scholar.

PY - 2012/12/10

Y1 - 2012/12/10

N2 - The resistance of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures was found to depend sensitively on their interfacial composition. Limiting the thickness of the first layer deposited (either Al or Ti) to a few nanometers resulted in low contact resistances after annealing for 1min at 500°C. The lowest contact resistance of 0.10 Ω mm (contact resistivity of 3×10-7 Ω cm2) was achieved with 3nm of Al as the first deposited layer. Transmission electron microscopy revealed a thin Ti-Al-Ga-N layer adjacent to the GaN in this annealed Al/Ti/Al contact, while the contact resistance was higher when the interfacial layer contained only Ti, Ga, and N. The simultaneous presence of Al and Ti next to GaN at the onset of reaction was found to be critical for achieving the lowest contact resistance.

AB - The resistance of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures was found to depend sensitively on their interfacial composition. Limiting the thickness of the first layer deposited (either Al or Ti) to a few nanometers resulted in low contact resistances after annealing for 1min at 500°C. The lowest contact resistance of 0.10 Ω mm (contact resistivity of 3×10-7 Ω cm2) was achieved with 3nm of Al as the first deposited layer. Transmission electron microscopy revealed a thin Ti-Al-Ga-N layer adjacent to the GaN in this annealed Al/Ti/Al contact, while the contact resistance was higher when the interfacial layer contained only Ti, Ga, and N. The simultaneous presence of Al and Ti next to GaN at the onset of reaction was found to be critical for achieving the lowest contact resistance.

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Extreme sensitivity of contact resistance to variations in the interfacial composition of Ti/Al-based contacts to N-face GaN/AlGaN heterostructures

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