Dislocation line charge screening within n-type gallium nitride

Abstract

A revised electrostatic theory for the charged dislocation lines within n-type GaN is formulated, this formalism allowing for the screening of the charge trapped along the dislocation lines, by both free carriers and a partial ionization of the impurities within the space-charge region surrounding the dislocation lines. This goes beyond the abrupt space-charge region assumption of the Read model [W. T. Read, Jr., Philos. Mag. 45, 775 (1954)], where the only screening mechanism considered is a complete ionization of bulk donor atoms within the Read radius. In addition to determining the spatial distribution of the charge enveloping charged dislocation lines, this procedure also provides a solution to the electrostatic potential surrounding the dislocation lines. An iterative, self-consistent numerical approach to the solution of this problem is developed for the purposes of this analysis. A special limit for which the results of this model reduce to that of Read is indicated. The results obtained from our analysis are found to be in satisfactory agreement with experimental results from the literature.