Interfacial microstructure and electrical properties of the Pt/Ti ohmic contact inp‐In0.53Ga0.47As formed by rapid thermal processing
作者:
S. N. G. Chu,
A. Katz,
T. Boone,
P. M. Thomas,
V. G. Riggs,
W. C. Dautremont‐Smith,
W. D. Johnston,
期刊:
Journal of Applied Physics
(AIP Available online 1990)
卷期:
Volume 67,
issue 8
页码: 3754-3760
ISSN:0021-8979
年代: 1990
DOI:10.1063/1.345018
出版商: AIP
数据来源: AIP
摘要:
The interfacial microstructure and electrical properties of the Pt/Ti ohmic contact top‐In0.53Ga0.47As (Zn: 5×1018cm−3) formed by rapid thermal processing (RTP) were intensively studied. Significant interdiffusion of Ti, In, and As across the interface, driven by RTP, occurred at temperatures of, or above, 350 °C for a heating duration of 30 s. A minimum specific contact resistance (9.0×10−6&OHgr; cm2) was achieved after heating at 450 °C. Cross‐sectional transmission electron microscopy of this sample revealed an interfacial reaction zone with complicated microstructure, and the dominant interfacial compound was identified to be InAs. Further increase in RTP temperature resulted in a change in the microstructure, and degradation of the contact resistance. The temperature‐dependence characteristic of the specific contact resistance of as‐deposited Pt/Ti contact to InGaAs revealed a thermionic‐emission‐dominated carrier‐transport mechanism with an effective barrier height &fgr;b, of 0.13 V. RTP treatment to the sample at elevated temperatures up to 450 °C decreased the temperature dependence of the contact resistance. This phenomenon strongly suggests a partial conversion of the dominant carrier‐transport mechanism across the contact area from thermionic emission to field emission. This was further verified by fitting the temperature dependence of the measured contact resistance to a phenomenological theory based on a linear combination of the two different types of carrier‐transport mechanisms operating at isolated area segments distributed uniformly across the interface.
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