Oxygen- and photoresist-related interface states of 4H-SiC Schottky diode observed by deep-level transient spectroscopy

Trap levels play an important role in semiconductor power devices. The barrier height of a metal-semiconductor junction, one of the important factors of unipolar devices, is influenced by the trap levels at its interface, i.e., interface states. However, there has not been much research on the interface states of Schottky diodes yet. Here, we report newly found KI₁, KI₂, and KI₃ interface states of 4H-SiC Schottky diodes. We observed their changes after the first deep-level transient spectroscopy measurements, in which temperature rises to 750 K, and discussed the origins of these changes by using X-ray photoelectron spectroscopy and scanning electron microscopy. The KI₁ was related to oxygen and photoresist (PR) residue, the KI₂ was related to oxygen, and the KI₃ was related to the PR residue.