The Impact of Active Layer Thickness on the Electrical Characteristics of Poly-Si Junctionless TFTs

Abstract

In this study we fabricated junction-less transistors and inversion-mode transistors and their electrical characteristic was measured and compared We found that subthreshold swing decreased as the channel thickness became thinner even lower than that of the traditional inversion-mode transistor On the other hand we also used TCAD simulation to verify the mechanism of device operation According to simulation results we found the subthreshold swing of the junction-less transistor is higher than that of the inversion-mode transistor with a long channel length of 100 nm However with a short channel length of 50 nm the subthreshold swing of the junction-less transistors is lower than that of an inversion-mode transistor This result can be attributed to the fact that the junction-less transistors has a longer effective channel length On the other hand we also investigated and compared the electrical characteristics of junction-less and inversion-mode transistors with different channel thickness We found that subthreshold swing of the junction-less transistors is higher than that of the inversion-mode transistor when the channel thickness is too thick (20 nm) This is because the gate is not able to completely depleted all carrier underneath resulting unwanted leakage currents

Date of Award	2017 Sept 4
Original language	English
Supervisor	Kuo-Hsing Kao (Supervisor)