The anomalous skin effect and the optical absorptivity of semiconductors I

Abstract

Synopsis After a brief review of the role played by the anomalous skin effect in the theory of optical absorption by metals, it is shown how the method of averaging over the distribution function, indicated in the author's recent paper on “pictorial kinetic methods in the theory of metals and semiconductors”, may be applied to derive tentative expressions for optical absorption by semiconductors. (The rigorous formal theory for semiconductors will be developed in a paper to follow). A detailed examination of the ways in which the carrier concentration and collision time in semiconductors can be expected to vary with temperature and impurity concentration, is followed by an assessment of the relative importance of the “Drude-Kronig” and “anomalous” terms in the optical absorption under various conditions. It is shown that the anomalous term can be very important in the wavelength range from 300 microns to 1 micron for semiconductors with a fairly large impurity concentration, but is comparatively unimportant for non-degenerate carrier systems unless the effective carrier mass is unusually small.