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Open Access Nano Review

Nanoscale electro-structural characterisation of ohmic contacts formed on p-type implanted 4H-SiC

Alessia Frazzetto13, Filippo Giannazzo1, Raffaella Lo Nigro1, Salvatore Di Franco1, Corrado Bongiorno1, Mario Saggio2, Edoardo Zanetti2, Vito Raineri1 and Fabrizio Roccaforte1*

Author Affiliations

1 Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi-Strada VIII, n. 5, Zona Industriale, 95121, Catania, Italy

2 STMicroelectronics, Stradale Primosole 50, 95121, Catania, Italy

3 Scuola Superiore di Catania, University of Catania, Via Valdisavoia, 9, 95123, Catania, Italy

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Nanoscale Research Letters 2011, 6:158  doi:10.1186/1556-276X-6-158

Published: 21 February 2011

Abstract

This work reports a nanoscale electro-structural characterisation of Ti/Al ohmic contacts formed on p-type Al-implanted silicon carbide (4H-SiC). The morphological and the electrical properties of the Al-implanted layer, annealed at 1700°C with or without a protective capping layer, and of the ohmic contacts were studied using atomic force microscopy [AFM], transmission line model measurements and local current measurements performed with conductive AFM.

The characteristics of the contacts were significantly affected by the roughness of the underlying SiC. In particular, the surface roughness of the Al-implanted SiC regions annealed at 1700°C could be strongly reduced using a protective carbon capping layer during annealing. This latter resulted in an improved surface morphology and specific contact resistance of the Ti/Al ohmic contacts formed on these regions. The microstructure of the contacts was monitored by X-ray diffraction analysis and a cross-sectional transmission electron microscopy, and correlated with the electrical results.