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 (ρ_c), sheet resistance (R_s), contact resistance (R_c), and transfer length (L_T) were calculated from resistance (R_T) versus contact spacing (d) measurements obtained from 17 TLM structures. The linear curves used for these calculations were fit to the R_T versus d data by calculating the standard error of linear regression of R_T on d; where, the average correlation coefficient with a straight line was 1.0000 and the average standard error of linear regression of R_T on d was 0.08 Ω. The resulting average values were: ρ_c=1.30×10⁻⁵ Ω cm², R_s=14.4 Ω/square, R_c=1.6 Ω, and L_T=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.