Effect of Impurity Correlation on the Density of States in Slightly Compensated Heavily Doped Semiconductors

概要

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A theory is developed of the electron density of states (DOS) in slightly conapensated heavilydoped semicondtnctors which undergo thermal treatment, taking adequately into account boththe ionic correlation and the electronic screening. The irnptrrity correlation is shown to weakentheir field via a high-temperature statistical screening. The free charge carriers weaken theirnptrrity field via the low-temperature electronic screening and, at the same tinne, they strengthenthe field by reducing the correlation degree via the statistical screening, An analytic expressionfor the DOS in the presence of correlated irnptrrities is derived within a senaiclassical approachto long-range fluctuations in the impvrn'ity potential. The DOS thus obtained is fotrnd to exhibitthe same energy dependence as in the Kane's theory for independent irnptrrities, but now withsome correlation-indtrced changes in the coefficients. In the high-energy tail region, our DOSis seen to be smaller th?rn the Kane's restrlt. For extremely strong correlation, our DOS tailbecomes negligibly small and, to describe the DOS tail observed in this limiting case, it mightbe necessary to invoke short-range potential fluctuations.
社団法人日本物理学会の論文
1997-01-15