METHODS OF DISLOCATION DISTRIBUTION ANALYSIS AND INCLUSION IDENTIFICATION WITH APPLICATION TO CDTE AND (CD,ZN)TE

Although the density of dislocations is used as an indicator of the qu ality of semiconductor wafers, it is also necessary to provide a descr iption of the dislocation distribution for those materials prone to po lygonization (namely the formation of sub-grain boundaries). In this w ork it is shown that visual inspection of etch pit distributions is in sufficient and that quantitative comparison with random distributions is more informative. This was achieved in two ways: (i) by comparison with a Poisson distribution and (ii) by using normalized radial disloc ation density plots, the former yielding the type of distribution and the latter the characteristic sub-grain tilting angle for the sample. Although these methods are general, examples for melt-and vapour-grown CdTe and (Cd, Zn)Te are given. Also reported upon in this work is the use of etching solutions to reveal inclusions in CdTe and (Cd, Zn)Te and hence permit their chemical identification by SEM/EDAX.