Effect of depth of traps in ZnO polycrystalline thin films on ZnO-TFTs performance
| Autor: | Rafael Ramírez-Bon, Manuel Quevedo-Lopez, R. Sánchez-Zeferino, L. A. Baldenegro-Pérez, M. I. Medina-Montes, Lizeth Rojas-Blanco, Marcelino Becerril-Silva |
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| Rok vydání: | 2016 |
| Předmět: |
010302 applied physics
Materials science Photoluminescence Argon Scanning electron microscope Gate dielectric Analytical chemistry Field effect chemistry.chemical_element 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Electronic Optical and Magnetic Materials chemistry Thin-film transistor Sputtering 0103 physical sciences Materials Chemistry Electrical and Electronic Engineering Thin film 0210 nano-technology |
| Zdroj: | Solid-State Electronics. 123:119-123 |
| ISSN: | 0038-1101 |
| Popis: | ZnO thin films were processed by radio frequency magnetron sputtering at room temperature on p-Si/SiO2 substrates under pure argon (Ar:O2 = 100:0 vol.%) and argon–oxygen mixture (Ar:O2 = 99:1 vol.%) gas environment. Morphological, optical and electrical characteristics of the ZnO films are reported, and they show a clear relationship with the gas mixture employed for the sputtering process. Scanning Electron Microscopy revealed the formation of grains of 15.3 and 19.9 nm average sizes and thicknesses of 59 nm and 82 nm for films growth in pure argon and argon–oxygen, respectively. Photoluminescence measurements at room temperature showed the violet emission band (centered at 3 eV) which was only detected in the ZnO film grown under pure argon. From thermally stimulated conductivity measurements two traps with 0.27 and 0.14 eV activation energies were identified for films grown in pure argon and argon–oxygen mixture, respectively. The trap at 0.27 eV is associated with a level located below the conduction band edge and it is supported by the PL band centered at 3 eV. Both types of ZnO films were used as the active channel layer in thin film transistors with thermal SiO2 as gate dielectric. Field effect mobility, threshold voltage and current ratio were improved in the devices with ZnO channel deposited with the argon–oxygen mixture (99% Ar/1% O2 vol.). Threshold voltage decreased from 25 V to 15 V, field effect mobility and current ratio increased from 0.8 to 2.4 cm2/Vs and from 102 to 106, in that order. |
| Databáze: | OpenAIRE |
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