Electron-beam-induced current study of electrical activity of dislocations in 4H-SiC homoeptaxial film

The types of dislocations and their electrical activity in 4H-SiC homoepitaxial film were characterized by molten KOH etching and electron-beam-induced current (EBIC) method. Chemical etching has revealed that there exists four kinds of dislocations, namely basal plane, screw, edge-I and edge-II dislocations. EBIC image has indicated that they are electrically active at room temperature, and the EBIC contrasts of such dislocations are stronger in the order of basal > screw > edge-I > edge-II. Their EBIC contrasts gradually decrease by cooling, which is different from those of clean dislocations in Si, suggesting that the dislocations are accompanied with deep levels. Secondary electron images of etch pits show that the sizes for screw and edge dislocations have the sequence of screw > edge-I > edge-II, suggesting their Burgers vectors decrease in this order. The EBIC contrasts of these dislocations are discussed in relation to their Burgers vectors.