| Summary: | 碩士 === 中華大學 === 電機工程學系碩士在職專班 === 100 === Most of Thin-Film-Transistors (TFTs) suffered from high threshold voltage (VT), poor sub-threshold swing (SS), and high operation voltage, still setting a limit on their applications. These issues mainly result from the use of low-k materials (such as SiO2) as gate dielectric film, which usually leads to poor gate control on the channel current. To overcome these problems originated from using low-κmaterials, high-κ materials need to be adopted as the gate dielectrics for the TFTs. In this study, Tantalum nitride (TaN) and Hafnium oxide (HfO2) / Zirconium oxide (ZrO2) were employed as the gate electrode and gate insulator, respectively. Because of the best stability for chemicals and good property with conductivity and transparency Tin oxide (SnO2) was employed as the channel layer.
The control group was fabricated in Tin oxide (SnO2) channel layer with none-annealing process compare to the Tin oxide channel layer with the same annealing process. Different thickness of gate dielectric layer was made to examine the leakage current influences on device characteristics also the annealing temperatures and times were made to realized the influences on TFT characterizes.
The amorphous properties of Tin oxide (SnO2) were confirmed by using X-Ray Diffraction (XRD) analysis technology. The thickness with 20 – 30 nm for Tin oxide had a transmittance of greater than 80% in visible wavelength. The max Id current, Ion/Ioff ratio, threshold voltage and sub-threshold swing obtained from the fabricated SnO2-TFTs with TaN(50 nm)/ HfO2(25 nm)/ ZrO2 (25 nm)/Al(300 nm) structure were 1.19 mA at Vgs = 2 V, 102-103, -1.6 V and 0.23V/dec, respectively.
In summary, our results revealed that HfO2 and ZrO2 multi-stacked structure gate dielectrics work well for future SnO2-TFTs.
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