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Type of Document Master's Thesis Author Wakchaure, Yogesh B Author's Email Address ywakchau@nd.edu URN etd-04162004-133549 Title LOW-RESISTANCE OHMIC CONTACTS TO p-InAs FOR HIGH-SPEED DEVICE APPLICATIONS Degree Master of Science Department Electrical Engineering Advisory Committee
Advisor Name Title Dr. Patrick Fay Committee Chair Dr. Debdeep Jena Committee Member Dr. Gregory Snider Committee Member Keywords
- frequency performance
- HBT
- InAs
- contact resistance
Date of Defense 2004-04-06 Availability restricted Abstract Evaluation of five different metallizations schemes for ohmic contact to p-type InAs was performed. The metallizations evaluated were Ti/Pt/Au, W/Ti/Au, Mo/Au, Cr/Au and Pd/Pt/Au. All the metals except W were deposited by electron beam evaporation; W was deposited by both sputtering and evaporation. Four different samples of InAs were used for this study. Contact resistance was measured using the transmission line method (TLM) with a Kelvin probe connection to minimize measurement error. Exploratory studies of the feasibility of reducing contact resistance through temperature annealing, as well as increasing the surface acceptor concentration through post-growth doping were undertaken. Most of the contacts showed improvement in the contact quality (as manifested by the specific contact resistance) with annealing. Ti/Pt/Au contacts exhibited the lowest contact resistance of 2 X 10^{-7} Omega mbox{cm}^{2}$ after annealing at $200 ^{o}$C for 5 minutes. A spin-on glass source was used with rapid thermal diffusion to introduce Zn acceptors into the InAs. Contrary to simple contact models, this process resulted in increased contact resistance.
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