Position correlations and space-charge noise suppression in solids at low frequencies

Abstract

Van Vliet and Fassett have settled the pattern for a more direct approach to the current noise problem. This method is applied here to the space-charge-limited current régime in a semiconductor. In this approach, position correlations between carrier concentrations were computed within the Debye-Hückel approximation, and the Green function for the carrier pulse drift on a non-neutral ground was determined with the aid of a specific physical hypothesis (drift without broadening). Noise spectral density distribution functions were computed in closed form for (i) the ideal dielectric diode (without traps) and (ii) the real dielectric diode (with compensated traps) in the limiting cases of very high and very low levels of injection. A space-charge noise suppression effect was found in all cases, except for the trap-compensated solid at very low level of injection. The suppression effect is highly complicated because of the trapping processes and is exerted on the pure shot noise as well as on the generation-recombination noise.