Schottky diode formation and characterization of titanium tungsten to n- and p-type 4H silicon carbide

Abstract

Titanium tungsten (Ti0.58W0.42) Schottky contacts to both n- and p-type 4H silicon carbide were fabricated using sputtering. The n- as well as p-type Schottky contacts had excellent rectifying characteristics after vacuum annealing at 500 degrees C with a thermally stable ideality factor of 1.06 +/- 0.03 for n-type and 1.08 +/- 0.01 for p-type. The measured Schottky barrier height (SBH) was 1.22 +/- 0.03 eV for n-type and 1.93 +/- 0.01 eV for p-type in the range of 24-300 degrees C. Our results of Ti0.58W0.42 Schottky contacts to both n- and p-type can be explained perfectly by thermionic emission theory and also satisfy the Schottky-Mott model in contrast to earlier works. Capacitance-voltage measurements were also performed and the results were in good agreement with those of current-voltage measurements. In addition, the inhomogeneous behavior with higher ideality factor and lower SBH of p-type Ti0.58W0.42 contacts for as-deposited contacts is explained by using a model with contribution of recombination current originated by lattice defects to thermionic emission current. (C) 2000 American Institute of Physics. [S0021-8979(00)05911-9].