Open AccessOn the Schottky Barrier Height Lowering Effect of Ti3SiC2 in Ohmic Contacts to P-Type 4H-SiC
Author(s) -
C Fisher,
Michael R. Jennings,
Yogesh Sharma,
A. Sanchez-Fuentes,
David Walker,
P. M. Gammon,
Amador PérezTomás,
S. M. Thomas,
S. E. Burrows,
Philip Mawby
Publication year - 2014
Publication title -
international journal of fundamental physical sciences
Language(s) - English
Resource type - Journals
ISSN - 2231-8186
DOI - 10.14331/ijfps.2014.330071
Subject(s) - ohmic contact , materials science , schottky barrier , annealing (glass) , silicon carbide , contact resistance , titanium , transmission electron microscopy , thermionic emission , epitaxy , tantalum carbide , silicon , aluminium , analytical chemistry (journal) , carbide , layer (electronics) , metallurgy , composite material , optoelectronics , nanotechnology , electron , chemistry , physics , diode , quantum mechanics , chromatography
In this paper, an experimental investigation into titanium (Ti) / aluminium (Al)-based ohmic contacts to p-type 4H-silicon carbide (SiC) has been presented. Electrical characterisation of the fabricated contacts showed that metal structures with an initial Ti layer yielded the lowest specific contact resistance (ρc), with a mean value of 3.7×10-5 Ω-cm2 being achieved after annealing in argon (Ar) at 1000°C for 2 minutes. Transmission electron microscopy (TEM) analysis illustrated the epitaxial relationship between the 4H-SiC and the as-deposited Ti layer, and, in conjunction with energy dispersive X-ray (EDX) analysis, showed that after annealing a ~5 nm thick layer of Ti3SiC2 was present, epitaxially arranged with the 4H-SiC. X-ray diffraction (XRD) analysis showed that the presence of the Ti3SiC2 metallic phase was more prevalent in the samples with Ti as the initial metal layer annealed at 1000°C, which corresponded with lower specific contact resistance. Fitting of experimental data to a thermionic field emission (TFE) model allowed the Schottky barrier height to be extracted; it was found that the lowest Schottky barrier heights were more prevalent where the most intense Ti3SiC2 phases were observed during XRD analysis.