Observation of Defects that Reduce Schottky Barrier Height in 4H-SiC Schottky Contacts Using Electrochemical Deposition of ZnO

Abstract

We performed the electrochemical deposition of ZnO on 4H-SiC epilayers and characterized Schottky diodes fabricated on the same epilayers in order to find the positions of defects that cause the low Schottky barrier height. We found that the positions where ZnO was deposited corresponded to the positions of contacts with lower Schottky barrier heights than the other contacts. After the removal of the ZnO layer, the surfaces of the ZnO-deposited positions were observed by atomic force microscopy. Photoluminescence mapping was also performed to observe the distribution of stacking faults. Then, the epilayer was etched using molten salt and the resulting etch pits were observed. Finally, we discussed the types of defects that reduce the Schottky barrier height.