Document Details
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Document Type |
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Thesis |
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Document Title |
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P-Type Metal Oxide Thin Film Transistors with Multilayer Channel and High-permittivity Gate Dielectric ترانزستورات أغشية أكسيد المعدن الرقيقة موجبة القطبية ذات القناة متعددة الطبقات والبوابة عالية العزل |
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Subject |
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Faculty of Science |
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Document Language |
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Arabic |
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Abstract |
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Metal oxides have emerged as promising materials to shape our future transparent flexible electronics. Several n-type oxides, such as a-IGZO, have been already studied and demonstrated their viability as active materials in thin film transistors (TFTs). Nonetheless, high performance p-type TFTs have remained hard to achieve. This study is devoted to investigate the capability of improving the performance of p-type TFTs by utilizing a high- 𝜅 gate dielectric material, on one hand, and employing the multilayer channel scheme, on the other. Moreover, the effect of buffering both sides of the transistor channel was explored.
Specifically, through the first part of this thesis, we aimed to optimize the dielectric characteristics of sputtered strontium titanate SrTiO3 (STO) thin films by investigating different annealing temperatures and two reactive oxygen ratios. Our exploration showed that films fabricated under a moderate power (60W), 10% O2 (STO10) and annealed at 300oC for 1hr have most elevated structural and electrical properties. Namely, STO10 @300 films revealed a smooth surface with RMS= 0.17 nm, high- 𝜅 of 54 and low energy loss of 0.12 at 1MHz. Noteworthy, the effect of applying Deep Ultraviolet-Ozone (DUV) photo-activation on STO as an alternative low-temperature approach was comprehensively investigated. Although the photoactivated STO films showed moderate dielectric properties, they could not be applied as TFT’s gate insulator due to their high surface roughness.
The second part of this thesis is assigned to adjust the electrical properties of sputtered cuprous oxide (Cu2O) thin films so they can be employed as the p-type channel in our fabricated TFTs. For this purpose, nitrogen (N2) was used as a dopant to enhance the channel hole-conduction, while thin layer of molybdenum trioxide (MoO3) was utilized to buffer back and front sides of the channel. On the top side, the thin MoO3 layer was capable of controlling the back-channel phase by forming a high resistance surface-path and hence reducing the drain off-current. While on the bottom side, the MoO3 layer worked as a buffer layer at the semiconductor/dielectric (CuxO /SrTiO3) interface which helped reducing the interface states density Dit by one order of magnitude. Via optimizing the N2-doping conditions and applying the bilayer channel scheme, switching characteristics were enhanced even more. Our best double-buffered bilayer TFT achieved a subthreshold swing of 0.14 V.dec-1, an on/off current ratio (Ion/Ioff) of 2.7×106, and a field-effect mobility (μFE) of 0.11 cm2.V-1.s-1, a considerable enhancement in performance compared to that of non-doped non-buffered CuxO TFTs.
Keywords: Sputtered cuprous oxide - High-𝜅 strontium titanate - Sputtered molybdenum trioxide- Deep ultraviolet-ozone photoactivation - Multilayer channel thin film transistors. |
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Supervisor |
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Prof. Hala Al Jawhari |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1444 AH
2022 AD |
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Added Date |
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Sunday, February 19, 2023 |
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Researchers
| أسماء يوسف مظفر | Mudhaffar, Asmaa Yousef | Researcher | Doctorate | |
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