Deformation-Induced Dislocations in 4H-SiC and GaN

Abstract

Bulk single crystals of 4H-SiC have been deformed in compression in the temperature range 550-1300°C, whereas a GaN thin film grown on a (0001) sapphire substrate was deformed by Vickers indentation in the temperature range 25-800°C. The TEM observations of the deformed crystals indicate that deformation-induced dislocations in 4H-SiC all lie on the (0001) basal plane but depending on the deformation temperature, are one of two types. The dislocations induced by deformation at temperatures above ~1 100°C are complete, with a Burgers vector, b, of 1/3❬112̄0❭ but are all dissociated into two 1/3❬101̄0❭ partials bounding a ribbon of stacking fault. On the other 3 hand, the dislocations induced by deformation in the temperature range 550<T<~ 1100°C were predominantly single leading partials each dragging a stacking fault behind them. From the width of dissociated dislocations in the high-temperature deformed crystals, the stacking fault energy of 4H-SiC has been estimated to be 14.7±2.5mJ/m². Vickers indentations of the [0001]-oriented GaN film produced a dense array of dislocations along the three <112̄0> directions at all temperatures. The dislocations were slightly curved with their curvature increasing as the deformation temperature increased. Most of these dislocations were found to have a screw nature with their b parallel to <112̄0>. Also, within the resolution of the weak-beam method, they were not found to be dissociated. Tilting experiment show that these dislocations lie on the {11̄00} prism plane rather than the easier (0001) glide plane.