THE INFLUENCE OF COMPOSITION FLUCTUATIONS ON THE SPIN TRANSITION SPECTRA OF SHALLOW DONORS IN SEMIMAGNETIC SEMICONDUCTORS

An original approach has been developed to describe shallow-donor spin -transition spectra in semimagnetic semiconductors for arbitrary impur ity content. The approach is based on the statistical theory of the ma gnetic resonance line shape. With this tool, the lower limit of the ma gnetic impurity concentration n(l) almost-equal-to 0.5a0(-3) is found at which the position of the resonance maximum E(m) may still be calcu lated in the mean exchange field approximation (a0 is the radius of th e shallow donor ground state). The upper limit, at which the nearest-n eighbour model is consistent for description of E(m), is found to be n (l) almost-equal-to 0.03a0(-3). A simple functional approximation of c omputed E(m) values is proposed in the impurity concentration range n( l) greater-than-or-equal-to 0.03a0(-3). A quantitative description is offered for earlier experimental results on the spin-flip Raman scatte ring by shallow donors in Cd1-xMnxS and EPR of shallow donors in ZnS:M n.