title: Nanoscale electro-structural characterisation of ohmic contacts formed on p-type implanted 4H-SiC.
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.
authors.affiliation: Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi-Strada VIII, n, 5, Zona Industriale, 95121, Catania, Italy. fabrizio.roccaforte@imm.cnr.it.
authors.forename: Alessia
authors.initials: A
authors.lastname: Frazzetto
authors.forename: Filippo
authors.initials: F
authors.lastname: Giannazzo
authors.forename: Raffaella
authors.initials: R
authors.lastname: Lo Nigro
authors.forename: Salvatore
authors.initials: S
authors.lastname: Di Franco
authors.forename: Corrado
authors.initials: C
authors.lastname: Bongiorno
authors.forename: Mario
authors.initials: M
authors.lastname: Saggio
authors.forename: Edoardo
authors.initials: E
authors.lastname: Zanetti
authors.forename: Vito
authors.initials: V
authors.lastname: Raineri
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Roccaforte