Influence of the substrate voltage on the random telegraph signal parameters in submicron n-channel metal-oxide-semiconductor field-effect transistors under a constant inversion charge density

In this paper, the impact of the substrate bias U-BS on the parameters of a repulsive random telegraph signal in an n-channel metal-oxide-semiconducto r field-effect transistor is studied. Particular attention is paid to the v ariation of the capture time constant tau(c) with the channel current I in linear operation. It is shown that the strong reduction of tau(C) with I ca n be explained by the Coulomb blockade effect. The corresponding Coulomb en ergy Delta E of the charged-near interface oxide trap is shown to be a stro ng function of the substrate bias. From the analysis of the experimental re sults considering surface quantization effects follows that the variation o f Delta E with U-BS is caused by the change in both the inversion layer sur face charge density N-s and in the surface electric field F-s that influenc es the distance between the centroid of the inversion layer and the interfa ce. In fact, it will be demonstrated that Delta E can be expressed in funct ion of a single parameter (NsFs2). Finally, the impact of the substrate bia s on the other parameters, i.e., the amplitude Delta I, the emission time c onstant tau(e) and the distance d of the trap from the interface, will also be addressed.