Performance Evaluation of W-C Alloy Schottky Contact for 4H-SiC Diodes

In this article, we investigate Schottky diodes with pure W and W-C alloy metal electrodes. The electrical characteristics of samples were analyzed by comparing the current density–voltage (<inline-formula> <tex-math notation="LaTeX">${J} - {V}$ </tex-math></inline-formula>) and capacitance–voltage (<inline-formula> <tex-math notation="LaTeX">${C} - {V}$ </tex-math></inline-formula>) curves at different annealing temperatures from 400 °C to 900 °C. The ideality factor of W-C alloy diodes annealed at 400 °C was 1.162. When W-C alloy diodes were annealed at 500 °C–900 °C, the range of <inline-formula> <tex-math notation="LaTeX">$\emptyset _{B}^{I-{V}}$ </tex-math></inline-formula> was merely 0.08 eV, the ideality factors were below 1.15, and the difference between <inline-formula> <tex-math notation="LaTeX">$\emptyset _{B}^{I-{V}}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\emptyset _{B}^{C-{V}}$ </tex-math></inline-formula> was smaller compared to the pure W diodes. For W-C alloy diodes annealed at 500 °C, the barrier height fluctuated only slightly, and the leakage current was suppressed effectively as the operating temperature increased. These results show that the new structure has better electrical characteristics and thermal stability. Meanwhile, transmission electron microscope (TEM) and energy-dispersive X-ray (EDX) images also verify that W-C alloy diodes reduce the interface reaction between the metal and silicon carbide (SiC), which improves the barrier inhomogeneity of W-based Schottky diodes effectively.