Weak-beam electron microscopy of faulted dipoles in deformed silicon

Abstract

Weak-beam electron microscopy of a deformed silicon crystal has revealed n high density (∼ 10 ^{7 mm −2 ) of faulted dipoles. This is believed to be the first time such defects have been observed in a non-metal. Detailed contrast experiments have shown that all the dipoles are of vacancy type in the Z configuration, a result that has also been reported for faulted dipoles in fatigued copper crystals. This suggests that the faulting reaction is not greatly affected by the covalent bonding in the silicon crystal, nor by details of the diamond crystal structure, nor by the mode of deformation. The specimen also contained a high density of unfaulted dipoles which consisted of roughly equal numbers of vacancy-and interstitial-type defects. The faulted and unfaulted dipoles together accounted for about one-half to two-thirds of the total dislocation density in the specimen, the remainder consisting of single primary dislocations plus a small density of secondaries.}