Browsing by Author "Shih, Cheng Wei"

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High Mobility SnO2 TFT for Display and Future IC
(2016)
Chin, Albert
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Shih, Cheng Wei
;
Lu, Chun Fu
;
Su, Wei Fang
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電子工程學系及電子研究所
Very high mobility of 149 +/- 189 cm(2)/Vs, large on-to-off current ratio (I-ON/I-OFF) of >7 orders of magnitude, fast turn-on sub-threshold swing of 110 mV/decade, and low power operation at 2 similar to 2.5 V were achieved in SnO2 TFT device at an ultra-thin SnO2 thickness of 4.5 nm. The device mobility of SnO2 TFT is higher than the best ZnO-based TFTs and CVD-grown multi-layers MoS2 MOSFETs. The reached mobility is already 0.7 times of universal mobility of SiO2/Si nMOSFET, operated typically at >= 1 MV/cm field. The very high mobility, simple low temperature process, and ultra-thin body SnO2 transistor should find its crucial role for high resolution display, future sub-10 nm nMOSFET and brain-mimicking 3D IC.
Low-Temperature Processed Tin Oxide Transistor With Ultraviolet Irradiation
(2019-06-01)
Shih, Cheng Wei
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Yen, Te Jui
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Chin, Albert
;
Lu, Chun Fu
;
Su, Wei Fang
Using a novel ultraviolet (UV) irradiation method, we processed a high-performance thin-film transistor (TFT) at low temperatures. Satisfactory device integrity that was demonstrated by high field-effect mobility values of 92 and 43 cm(2)/Vs, small subthreshold slopes of 74 and 81 mV/decade, and ON-current/OFF-current values of 3 x 10(6) and 7 x 10(5) was achieved for the SnO2 TFT at low processing temperatures of 180 degrees C and 100 degrees C, respectively. The results of X-ray photoelectron spectroscopy showed that the UV irradiation considerably increased the presence of Sn4+ and reduced the presence of unwanted Sn2+, even at low processing temperatures, improving the quality of SnO2.
New Material Transistor with Record-High Field-Effect Mobility among Wide-Band-Gap Semiconductors
(2016-08-03)
Shih, Cheng Wei
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Chin, Albert
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
At an ultrathin 5 nm, we report a new high-mobility tin oxide (SnO2) metal-oxide-semiconductor field-effect transistor (MOSFET) exhibiting extremely high field-effect mobility values of 279 and 255 cm(2)/V-s at 145 and 205 degrees C, respectively. These values are the highest reported mobility values among all wide-band-gap semiconductors of GaN, SiC, and metal-oxide MOSFETs, and they also exceed those of silicon devices at the aforementioned elevated temperatures. For the first time among existing semiconductor transistors, a new device physical phenomenon of a higher mobility value was measured at 45-205 degrees C than at 25 degrees C, which is due to the lower optical phonon scattering by the large SnO2 phonon energy. Moreover, the high on-current/off-current of 4 x 10(6) and the positive threshold voltage of 0.14 V at 25 degrees C are significantly better than those of a graphene transistor. This wide-band-gap SnO2 MOSFET exhibits high mobility in a 25-205 degrees C temperature range, a wide operating voltage of 1.5-20 V, and the ability to form on an amorphous substrate, rendering it an ideal candidate for multifunctional low-power integrated circuit (IC), display, and brain-mimicking three-dimensional IC applications.
Optical Properties of TiO2 Films Deposited by Reactive Electron Beam Sputtering
(2017-10-01)
Kruchinin, V. N.
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Perevalov, T. V.
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Atuchin, V. V.
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Gritsenko, V. A.
;
Komonov, A. I.
Titanium dioxide (anatase, a-TiO2) films have been prepared by electron beam sputtering of a TiO2 target in reactive atmosphere and their structural, microstructural, and optical properties were evaluated by reflection high- energy electron diffraction (RHEED) and x-ray diffraction (XRD) analyses, atomic force microscopy (AFM), and spectroscopic ellipsometry (SE). Different reflection models for determination of film optical parameters were tested and compared. The dispersive optical parameters were defined using the Tauc-Lorentz model by SE in the photon energy range of E = 1.12-4.96 eV. The films were transparent at E < 3 eV, but noticeable absorption was detected at E > 3 eV. The bandgap was estimated at the level of E (g) ae 3.44 eV.
Remarkably High Hole Mobility Metal-Oxide Thin-Film Transistors
(2018-01-17)
Shih, Cheng Wei
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Chin, Albert
;
Lu, Chun Fu
;
Su, Wei Fang
;
電子工程學系及電子研究所
High performance p-type thin-film transistor (p-TFT) was realized by a simple process of reactive sputtering from a tin (Sn) target under oxygen ambient, where remarkably high field-effect mobility (mu(FE)) of 7.6 cm(2)/Vs, 140 mV/dec subthreshold slope, and 3 x 10(4) on-current/off-current were measured. In sharp contrast, the SnO formed by direct sputtering from a SnO target showed much degraded mu(FE), because of the limited low process temperature of SnO and sputtering damage. From the first principle quantum-mechanical calculation, the high hole mu(FE) of SnO p-TFT is due to its considerably unique merit of the small effective mass and single hole band without the heavy hole band. The high performance p-TFTs are the enabling technology for future ultra-low-power complementary-logic circuits on display and three-dimensional brain-mimicking integrated circuits.
Remarkably High Mobility Thin-Film Transistor on Flexible Substrate by Novel Passivation Material
(2017-04-25)
Shih, Cheng Wei
;
Chin, Albert
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
High mobility thin-film transistor (TFT) is crucial for future high resolution and fast response flexible display. Remarkably high performance TFT, made at room temperature on flexible substrate, is achieved with record high field-effect mobility (mu(FE)) of 345 cm(2)/Vs, small sub-threshold slope (SS) of 103 mV/dec, high on-current/off-current (I-ON/I-OFF) of 7 x 10(6), and a low drain-voltage (V-D) of 2 V for low power operation. The achieved mobility is the best reported data among flexible electronic devices, which is reached by novel HfLaO passivation material on nano-crystalline zinc-oxide (ZnO) TFT to improve both I-ON and I-OFF. From X-ray photoelectron spectroscopy (XPS) analysis, the non-passivated device has high OH-bonding intensity in nano-crystalline ZnO, which damage the crystallinity, create charged scattering centers, and form potential barriers to degrade mobility.