Thermally stable, low specific resistance (1.30×10−5 Ω cm2) TiC Ohmic contacts to n-type 6Hα-SiC

Abstract

An array of transfer length measurement (TLM) structures was formed on an electrically isolated (0001) n+6Hα-SiC epilayer. The n+6Hα-SiC epilayer contained an in situ incorporated nitrogen concentration of 4×1019 cm−3. The specific contact resistance (ρc), sheet resistance (Rs), contact resistance (Rc), and transfer length (LT) were calculated from resistance (RT) versus contact spacing (d) measurements obtained from 17 TLM structures. The linear curves used for these calculations were fit to the RT versus d data by calculating the standard error of linear regression of RT on d; where, the average correlation coefficient with a straight line was 1.0000 and the average standard error of linear regression of RT on d was 0.08 Ω. The resulting average values were: ρc=1.30×10−5 Ω cm2, Rs=14.4 Ω/square, Rc=1.6 Ω, and LT=9.5 μm. The (111) TiC contacts, epitaxially grown by chemical vapor deposition, were thermally and chemically stable at 1400 °C. The TiC contacts could not be scratched with a tungsten carbide scriber, nor delaminated from the 6Hα-SiC substrate.