The properties were studied as a function of the dislocation density. Measurements which were performed on samples with a graded dislocation density (ranging from about 2 x 105 to 2 x 106/cm2) revealed that the net dopant concentration was independent of the local dislocation density, while the MIS dark current varied linearly with dislocation density. No evidence of impurity segregation to dislocations was observed for dislocation densities in the above range. Hall measurements which were performed on n-type samples, before and after 2% plastic deformation, showed that the net donor density increased by 1014 to 2 x 1014/cm3; possibly due to residual point defects which were generated by the deformation. The electron mobility at low temperatures decreased by about an order of magnitude, due to increased scattering from charged dislocations. The density of the latter increased by a factor of more than 100. Deformed material exhibited a larger decrease in electron mobility after low-temperature plasma hydrogenation than did undeformed samples. It was suggested that the dislocation density could affect the H solubility of the samples. The present results suggested that the dislocations themselves did not contribute to the carrier concentration in this material.

J.H.Tregilgas, T.L.Polgreen, M.C.Chen: Journal of Crystal Growth, 1988, 86[1-4], 460-6