Scaling and parasitic effects in ZnO transparent thin film transistors
Journal
Proceedings of SPIE - The International Society for Optical Engineering
Journal Volume
6474
Date Issued
2007
Author(s)
Abstract
Scaling behaviors of ZnO transparent thin-film transistors (TTFTs) have been studied by fabricating series of miniaturized ZnO TTFTs having various channel widths and lengths. Mobility of >8 cm2/V·S and on/off ratio of up to 107 are achieved with these TTFTs. Results show, that these ZnO TTFTs retain rather well-behaved transistor characteristics down to the channel length of ∼5 μm, rendering possible high-resolution applications. More apparent short-channel effects (e.g., lowering of threshold voltages, degradation of the subthreshold slope with the decrease of the channel length and the increase of the drain voltage, and loss of hard saturation, etc.) are observed when the channel length is reduced below 5 μm. Influences of parasitic effects on TFT characteristics are also studied by extracting parasitic resistance and channel resistance using devices of various dimensions. The ratio of parasitic resistance to channel resistance at VG = 10 V was increased from 0.04 to 0.36, when the channel length decreased from 20 μm to 2 μm. This indicates that parasitic resistance has substantial influences on device performances (e.g., output drain current, apparent field effect mobility, etc.) when the channel length is reduced, and better contact techniques may be required.
Type
conference paper