Bulk single crystals of 4H-SiC were deformed in compression at 550 to 1300C, while GaN thin films grown on a (00•1) sapphire substrate were deformed by Vickers indentation at 25 to 800C. Transmission electron microscopic observations of the deformed crystals indicated that deformation-induced dislocations in 4H-SiC all lay on the (00•1) basal plane but, depending upon the deformation temperature, could be of two types. The dislocations introduced by deformation above about 1100C were complete, with a Burgers vector of 1/3<11•0> but were all dissociated into two 1/3<10•0> partials bounding a ribbon of stacking fault. On the other hand, the dislocations introduced by deformation at 550 to 1100C were predominantly single leading partials; each dragging a stacking fault behind them. From the width of the dissociated dislocations in the high-temperature deformed crystals, the stacking-fault energy of 4H-SiC was estimated to be 14.7mJ/m2. Vickers indentation of the [00•1]-oriented GaN film produced a dense array of dislocations along the three <11•0> 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 Burger’s vector parallel to <11•0>. Within the resolution of the weak-beam method, they were not dissociated. Tilting experiments showed that these dislocations lay on the {1¯1•0} prism-plane rather than the easier (00•1) glide plane.

Deformation-Induced Dislocations in 4H-SiC and GaN. M.H.Hong, A.V.Samant, V.Orlov, B.Farber, C.Kisielowski, P.Pirouz: Materials Research Society Symposium – Proceedings, 1999, 572, 369-75