Arrangements of Dislocations in Plastically Bent Silicon Crystals

Abstract

Dislocations introduced into single crystals of silicon by plastic bending at an elevated temperature have been studied quantitatively by the etch-pit technique. The average etch-pit density after deformation is approximately two to three times higher than the calculated dislocation density. Prolonged annealing of the deformed samples at a temperature close to the melting point results in polygonization or the alinement of etch pits perpendicular to the active slip planes. Satisfactory agreement was obtained between the densities of etch pits in the annealed and polygonized specimens and the predicted dislocation densities. Piled-up horizontal arrays of etch pits have been observed in lightly bent samples. The value of yield stress obtained from the geometrical distribution of these arrays is an order of magnitude below the reported experimental values. Dislocation lines in single crystals deformed at 1000°C have been revealed by the technique of copper decoration. Examination of the decorated samples by infrared transmission microscopy revealed that the dislocation lines lie in the [211] direction.