Ohmic contact formation in palladium-based metallizations to n-type InP
- Univ. of Alberta, Edmonton (Canada)
- Bell Northern Research, Ltd., Ottawa (Canada)
Two Pd-based metallizations have been systematically studied, i.e., Au/Ge/Pd and Pd/Ge contacts to n-type InP, in an attempt to better understand the role of the metallization constituents in forming ohmic contacts. Ohmic contacts were obtained with minimum specific resistances of 2.5 x 10{sup {minus}6} {Omega}-cm{sup 2} and 4.2 x 10{sup {minus}6} {Omega}-cm{sup 2} for the Au/Ge/Pd and the Pd/Ge contacts, respectively. The annealing regime for ohmic contact formation is 300-375{degree}C for the Au/Ge/Pd/InP system and 350-450{degree}C for the Pd/GeInP system. Palladium, in both cases, reacts with InP to form an amorphous layer and then an epitaxial layer at low temperatures, providing good metallization adhesion to InP substrates and improved contact morphology. Ohmic contact formation in both contacts is attributed to Ge doping, based on the solid state reaction-driven decomposition of an epitaxial layer at the metallization/InP interface, producing a very thin, heavily doped InP layer. Gold appears to be responsible for the difference in contact resistance in the two systems. It is postulated that Au reacts strongly with In to form Au-In compounds, creating additional In site vacancies in the InP surface region (relative to the Au-free metallization), thereby enhancing Ge doping of the InP surface and lowering the contact resistance. 21 refs., 7 figs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 62435
- Report Number(s):
- CONF-9302103--
- Journal Information:
- Journal of Electronic Materials, Journal Name: Journal of Electronic Materials Journal Issue: 9 Vol. 23; ISSN JECMA5; ISSN 0361-5235
- Country of Publication:
- United States
- Language:
- English
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