One model of flicker, burst, and generation-recombination noises

An earlier model of the flicker noise is improved and extended and a unified theory of the flicker, burst, and generation-recombination (g-r) noises is achieved. To this end the effects on the carrier and current densities of the electric potential and quasi-Fermi-level fluctuations, both inside and outside the islands generating the noise, are taken into account. General expressions are so obtained for the impedance field, the current dipole induced by the island charge fluctuations, and, chiefly, for thier correlation time. This one is proportional to the series of the internal and external capacitances of the island and it becomes proportional to the first one only when the island sizes become smaller than a proper discriminant value $\Lambda$. From such results then, it is deduced that a single defect containing only one state generates burst noise if it is located in a region with a high current density which amplifies its bistable fluctuations, whereas the islands having a single deep energy level produce g-r noise. The flicker noise, instead, is originated by islands, with sizes both greater and smaller than $\Lambda$, having a broad energy-level dispersion and, in virtue of tunnel emission, also by one-level islands enclosed by an energy barrier. Finally, for the nondegenerate media and islands with sizes smaller than Debye's length, the Hooge empirical formula is deduced theoretically in an exact way, and we show that its constant is directly proportional to the volume fraction occupied by the islands and it is inversely proportional to the standard deviation of the logarithm of the island resistance.