Microstructure of Ti/Al and Ti/Al/Ni/Au Ohmic contacts forn‐GaN
作者:
S. Ruvimov,
Z. Liliental‐Weber,
J. Washburn,
K. J. Duxstad,
E. E. Haller,
Z.‐F. Fan,
S. N. Mohammad,
W. Kim,
A. E. Botchkarev,
H. Morkoc¸,
期刊:
Applied Physics Letters
(AIP Available online 1996)
卷期:
Volume 69,
issue 11
页码: 1556-1558
ISSN:0003-6951
年代: 1996
DOI:10.1063/1.117060
出版商: AIP
数据来源: AIP
摘要:
Transmission electron microscopy has been applied to characterize the structure of Ti/Al and Ti/Al/Ni/Au Ohmic contacts onn‐type GaN (∼1017cm−3) epitaxial layers. The metals were deposited either by conventional electron‐beam or thermal evaporation techniques, and then thermally annealed at 900 °C for 30 s in a N2atmosphere. Before metal deposition, the GaN surface was treated by reactive ion etching. A thin polycrystalline cubic TiN layer epitaxially matched to the (0001) GaN surface was detected at the interface with the GaN substrate. This layer was studied in detail by electron diffraction and high resolution electron microscopy. The orientation relationship between the cubic TiN and the GaN was found to be: {111}TiN//{00.1}GaN, [110]TiN//[11.0]GaN, [112]TiN//[10.0]GaN. The formation of this cubic TiN layer results in an excess of N vacancies in the GaN close to the interface which is considered to be the reason for the low resistance of the contact. ©1996 American Institute of Physics.
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