Ni-silicide contacts to 6H-SiC: contact resistivity and barrier height on ion implanted n-type and barrier height on p-type epilayer

Recently Ni/SiC contacts have been studied in order to achieve very low contact resistivity (rc) values on n-type SiC. In this work contact resistivity values of Ni-silicide contacts to n-type ion implanted 6H-SiC are analyzed aiming at extracting the Schottky Barrier Height (SBH). The n-type ion implanted 6H-SiC specimens were annealed at 1300, 1500, 1650°C for 20 min in a high purity Ar ambient. The contact resistivity values have been extracted from Transmission Line Method (TLM) measurements in the range of temperatures 25-290°C. The rc values are in the range 1-5×10^(-5) ohm cm2 depending on the annealing temperature. The SBH Phi_(Bn) has been extracted by exploiting the dependence of the contact resistivity on the temperature. By using the field emission model, the value obtained for fBn on our samples is in the range 1.1-1.3 eV depending on the annealing temperature. The SBH on p-type 6H-SiC has been evaluated on Schottky diodes by means of both IV and C-V measurements. A value of qfBp= (1.75±0.05) eV has been obtained on p-type SiC through the C-V method. The average SBH extracted from I-V data collected at room temperature is (1.19±0.03) eV and this value increases as a function of the temperature until (1.50±0.01) eV at 290°C. Differences between values of SBH extracted from I−V and from C−V measurements are explained in terms of inhomogeneous barrier height