Analysis of Back-Gate Voltage Dependence of Threshold Voltage of Thin Silicon-on-Insulator Metal-Oxide-Semiconductor Field-Effect Transistor and Its Application to Si Single-Electron Transistor

摘要

The back-gate voltage (v_(bg)) dependence of threshold voltage (v_(th)) is analyzed for n- and p-channel thin silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) using a self-consistent solution of the coupled Poisson and Schroedinger equations with a variational method. It is found that the slope (dV_(th)/dV_(BG)) is modulated not only by the gate-oxide and buried-oxide thickness but also by the distribution of the wave functions of carriers in the SOI layer and that the slope can be well described by an approximate equation derived assuming that a δ-function-like charge sheet exists at the average position of carriers in the SOI layer. From these findings, SOI-layer thickness and gate-oxide thickness or average position of carriers are shown to be determined precisely. Moreover, from the back-gate voltage dependence of peak voltage (defined as the gate voltage giving a drain current peak) of a single-electron transistor (SET), the average position of electrons in a Si island is shown to change, particularly in the few-electron regime, probably due to electron-electron interaction.