DECOMPOSITION OF TRANSPORT NOISE UNDER SPACE CHARGE CONDITIONS IN SOLIDS

The general linear markoffian theory of the transport noise in solids has been re-examined ab initio from the point of view of a non-local decomposition of the noise (into thermal noise, current noise and coupling noise) which exhibits the effect of the spatial correlations between carrier concentrations and velocities. For the space-charge-limited current régime, at frequencies low enough to permit the neglect of displacement current, the following results were obtained: a) The three types of noise are of the same order of magnitude, the coupling noise being negative; b) The spectral noise density has essentially the Nyquist form (with a current-dependent resistance), leading to a suppression effect of the current noise, the suppression factor being of the order of kT/eUa (Ua being the applied voltage). These conclusions were used to explain the apparent predominance of the thermal noise found in recent experiments. © 1968.