Schottky Barrier Height Dependence on the Metal Work Function for p-type 4H-Silicon Carbide

Authors: Lee, S.K.; Zetterling, C.M.; Östling, M.

Source: Journal of Electronic Materials, Volume 30, Number 3, 1 March 2001 , pp. 242-246(5)

Publisher: Springer

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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°C to 300°C. 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 I-V characteristics. Based on our measurements for p-type 4H-SiC, the SBH (φ_Bp) and metal work functions (φ_m ) show a linear relationship of φ_Bp = 4.58 - 0.61φ_m and φ_Bp = 4.42 - 0.54φ_m 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 ≡ φ_Bp/φ_m) of 0.58 even though the Fermi level is partially pinned. We found the sum of the SBH (φ_Bp + φ_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.

Keywords: SCHOTTKY BARRIER DIODES; RECTIFICATION; FERMI-LEVEL PINNING; WORK FUNCTION; 4H-SIC

Document Type: Research article

Publication date: 2001-03-01