A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures

Journal Article · Mon Jun 29 04:00:00 EDT 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4923468· OSTI ID:22483115

Pristavu, G.; Brezeanu, G.; Badila, M. ^[1]; Pascu, R. ^[1]; Danila, M. ^[2]; Godignon, P. ^[3]

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1. Electronics, Telecommunications and Information Technology, University Politehnica Bucharest, Bucharest 061071 (Romania)
2. National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae Street 126A, 077190 Bucharest (Romania)
3. Centro Nacional de Microelectronica, C/del Tillers, Campus Universitat Autònoma de Barcelona, 08193 Barcelona (Spain)

Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (Φ{sub Bn,l}) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured I{sub F}–V{sub F}–T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni{sub 2}Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni{sub 2}Si/4H-SiC Schottky contacts.

• OSTI ID: 22483115
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 26 Vol. 106; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANNEALING
DROPLETS
ELECTRICAL PROPERTIES
INTERFACES
NICKEL SILICIDES
SILICON CARBIDES
SURFACES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 1000-4000 K
VARIATIONS
X-RAY DIFFRACTION