High Field Temperature-Independent Field-Effect Mobility of Amorphous Indium–Gallium–Zinc Oxide Thin-Film Transistors: Understanding the Importance of Equivalent-Oxide-Thickness Downscaling
| Autor: | Subhranu Samanta, Ying Wu, Xiao Gong, Shengqiang Xu, Kaizhen Han |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
010302 applied physics
Physics Condensed matter physics Gate dielectric Fermi level Temperature independent Field effect Biasing Equivalent oxide thickness 01 natural sciences Electronic Optical and Magnetic Materials Amorphous solid symbols.namesake Thin-film transistor 0103 physical sciences symbols Electrical and Electronic Engineering |
| Zdroj: | IEEE Transactions on Electron Devices. 68:118-124 |
| ISSN: | 1557-9646 0018-9383 |
| DOI: | 10.1109/ted.2020.3035737 |
| Popis: | We investigate the temperature dependence of field-effect mobility ( $\mu _{eff}$ ) on amorphous indium–gallium–zinc oxide ( $\alpha $ -IGZO) thin-film transistors (TFTs) having 10-nm-thick HfO2. Thanks for the downscaling of the equivalent oxide thickness (EOT), we observe, for the first time, a temperature-independent $\mu _{eff}$ at a high field or high carrier concentration ( ${N}_{carrier}$ ) regime and a strong temperature-dependent $\mu _{eff}$ at a low field or low ${N}_{carrier}$ regime. The observation highlights the importance of EOT downscaling to enhance ${N}_{carrier}$ and facilitate the Fermi level ( ${E}_{F}$ ) to approach and even exceed the potential barriers’ peak ( ${E}_{M}$ ), leading to a high and temperature-independent $\mu _{eff}$ at high ${N}_{carrier}$ . ${N}_{carrier}$ at which ${E}_{\textbf {F}} = {E}_{M}$ is extracted to be $\sim 6\times 10^{12}$ cm−2. A detailed study of the relationship between EOT scaling and the gate bias voltage ( ${V}_{GS}$ ) at which ${E}_{F}$ equals to ${E}_{M}$ is performed. $\alpha $ -IGZO TFTs with an ultrascaled gate dielectric are capable of alleviating the negative effects from the potential barriers at low ${V}_{GS}$ and could enable low-power applications with high performance. Besides, a weak temperature-dependent subthreshold swing (SS) of $\alpha $ -IGZO TFT was observed and explained. |
| Databáze: | OpenAIRE |
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