Schottky barrier height dependence on the metal work function for p-type 4H-silicon carbide

Abstract

We investigated Schottky barrier diodes of several metals (Ti, Ni, and Au) having different metal work functions to p-type 4H-SiC (0001) using I-V and C-V characteristics. Contacts showed excellent Schottky behavior with stable ideality factors of 1.07, 1.23, and 1.06 for Ti, Ni, and Au, respectively, in the range of 24 degreesC to 300 degreesC. The measured Schottky barrier height (SBH) was 1.96, 1.41, and 1.42 eV for Ti, Ni, and Au, respectively, in the same temperature range from IV characteristics. Based on our measurements for p-type 4H-SiC, the SBH (phi (Bp)) and metal work functions (phi (m)) show a linear relationship of phi (Bp) = 4.58 - 0.61 phi (m) and phi (Bp) = 4.42 - 0.54(phim) for I-V and C-V characteristics at room temperature, respectively. We observed that the SBH strongly depends on the metal work function with a slope (S = phi (Bp)/phi (m)) of 0.58 even though the Fermi level is partially pinned. We found the sum of the SBH (phi (Bp) + phi (Bn) = E-g) at room temperature for nand p-type 4H-SiC to be 3.07 eV, 3.12 eV, and 3.21 eV for Ti, Ni, and Au, respectively, using I-V and C-V measurements, which are in reasonable accord with the Schottky-Mott limit.