Barrier height determination of SiC Schottky diodes by capacitance and current–voltage measurements

Extractions of barrier heights of 6H and 4H-SiC Schottky diodes have been performed on structures with various gate metallization, using both capacitance–voltage (C–V) and current–voltage (I–V) measurements. The sum of the two barriers extracted by C–V measurements on both n-type and p-type materials is found to be higher than the band gap energy EG, whereas the one extracted by I–V is less than EG. However, above room temperature, temperature variations of barrier heights are in agreement with the variations of EG. We have also computed theoretical I–V characteristics using a two-barrier height model. By taking account of temperature variations of a large number of parameters, e.g., the carrier mobility, free carrier concentration, and barrier height, we have achieved a good fit with experimental data. The model is shown to be valid for n-type Schottky diodes over a wide range of temperatures (from 100 to 500 K).