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

Abstract.

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-semiconductor field-effect transistor is studied. Particular attention is paid to the variation of the capture time constant τ_c with the channel current I in linear operation. It is shown that the strong reduction of τ_c with I can be explained by the Coulomb blockade effect. The corresponding Coulomb energy ΔE of the charged-near-interface oxide trap is shown to be a strong function of the substrate bias. From the analysis of the experimental results considering surface quantization effects follows that the variation of ΔE with U _BS is caused by the change in both the inversion layer surface charge density N _s and in the surface electric field F _s that influences the distance between the centroid of the inversion layer and the interface. In fact, it will be demonstrated that ΔE can be expressed in function of a single parameter (N _s F _s ²). Finally, the impact of the substrate bias on the other parameters, i.e., the amplitude ΔI, the emission time constant τ_e and the distance d of the trap from the interface, will also be addressed.