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Thermally Stable Carbon Based Ohmic Contact to P-type GaAs

IP.com Disclosure Number: IPCOM000110260D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Callegari, A: AUTHOR [+4]

Abstract

Disclosed is a carbon-based ohmic contact to p-type GaAs which is formed by rapid thermal annealing at temperatures in excess of 900oC. The contact remains stable upon subsequent stressing at 400oC for a number of hours.

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Thermally Stable Carbon Based Ohmic Contact to P-type GaAs

       Disclosed is a carbon-based ohmic contact to p-type GaAs
which is formed by rapid thermal annealing at temperatures in excess
of 900oC.  The contact remains stable upon subsequent stressing at
400oC for a number of hours.

      The contact consists of the Ni/C/W trilayer shown in Fig. 1.
Carbon is a shallow acceptor when incorporated on the As sublattice
and has a much lower diffusion coefficent than the more traditional
dopants, i.e., Mg and Zn.  In addition, C reacts with Ni to form
highly stable Ni carbide phases when annealed at high temperatures.
The refractory W layer is used to obtain the required metal sheet
resistance.

      Fig. 2a shows the contact characteristics before annealing,
indicative of a Schottky diode with a barrier height of ~0.5 eV.  The
transition to ohmic behavior is shown in Fig. 2b for a sample
annealed at 920oC for 2 seconds.  Transmission line measurements
yielded a contact resistance of ~1 L-mm which remained unchanged
after 2 hours at 400oC.