Browsing by Author "Su, Sheng-Kai"

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Demonstration of 40-nm Channel Length Top-Gate p-MOSFET of WS2 Channel Directly Grown on SiOx/Si Substrates Using Area-Selective CVD Technology
(2019-12-01)
Chung, Yun-Yan
;
Lu, Kuan-Cheng
;
Cheng, Chao-Ching
;
Li, Ming-Yang
;
Lin, Chao-Ting
For high-volume manufacturing of 2-D transistors, area-selective chemical reaction deposition (CVD) growth is able to provide good-quality 2-D layers and may be more effective than exfoliation from bulk crystals or wet/dry transfer of large-area as-grown 2-D layers. We have successfully grown continuous and uniform WS2 film comprising around seven layers by area-selective CVD approach using patterned tungsten source/drain metals as the seeds. The growth mechanism is inferred and supported by the transmission electron microscope (TEM) images, as well. The first top-gate MOSFETs of CVD-WS2 channels on SiOx/Si substrates are demonstrated to have good short channel electrical characteristics: ON-/OFF-ratio of 10(6), a subthreshold swing of 97 mV/decade, and nearly zero drain-induced barrier lowering (DIBL).
First demonstration of 40-nm channel length top-gate WS2 pFET using channel area-selective CVD growth directly on SiOx/Si substrate
(2019-01-01)
Cheng, Chao-Ching
;
Chung, Yun-Yan
;
Li, Ming-Yang
;
Lin, Chao-Ting
;
Li, Chi-Feng
Area-selective channel material growth for 2D transistors is more desirable for volume manufacturing than exfoliation or wet/dry transfer after large area growth. We demonstrate the first top-gate WS(2)p-channel field-effect transistors (p-FETs) fabricated on SiOx/Si substrate using channel area-selective CVD growth. Smooth and uniform WS2 comprising approximately 6 layers was formed by area-selective CVD growth in which a patterned tungsten-source/drain served as the seed for WS2 growth. For a 40 nm gate length transistor, the device has impressive electrical characteristics: on/off ratio of similar to 10(6), a S.S. of similar to 97 mV/dec.. and nearly zero DIBL.
GaAs Polariton Interference in Magnetic Field: Oblique Incident Ellipsometry Measurement
(2014-11-15)
Su, Sheng-Kai
;
Voskoboynikov, Oleksandr
;
Li, Liang-Chen
;
Suen, Yuen-Wuu
;
Lee, Chien-Ping
The properties of GaAs polaritons propagating in a magnetic field have been investigated using a self-designed ellipsometry system with an oblique incident angle. Interesting fine structures, which have not been reported, have been observed and their magneto-optical behavior cannot be explained by the known properties of excitonic states. Treating the surface and the growth interface as boundaries, we attribute the fine structures to the interference among various polariton modes. A model considering the polariton spatial dispersion and exciton effective mass increase induced by its center of mass and relative motion coupling is proposed to explain the magnetic response of interference ellipsometry spectra.
Low temperature and high magnetic field spectroscopic ellipsometry system
(2014-05-01)
Su, Sheng-Kai
;
Li, Liang-Chen
;
Suen, Yuen-Wuu
;
Wu, Jau-Yang
;
Kuo, Hong-Rong
We report on the design and implementation of a spectral ellipsometer at near-infrared wavelength (700-1000 nm) for samples placed in high magnetic fields (up to 14 T) at low temperatures (similar to 4.2 K). The main optical components are integrated in a probe, which can be inserted into a conventional long-neck He dewar and has a very long free-space optical path (similar to 1.8 mx2). A polarizer-sample-(quarter-wave plate)-rotating analyzer configuration was employed. Two dielectric mirrors, one before and one after the sample in the optical path, helped to reflect the light back to the analyzer and a two-axis piezo-driven goniometer under the sample holder was used to control the direction of the reflected light. Functional test results performed on an intrinsic GaAs wafer and analysis on the random error of the system are shown. We obtained both amplitude and phase ellipsometric spectra simultaneously and observed helicity transformation at energies near the GaAs exciton transitions in the phase spectra. Significant shifts of them induced by magnetic fields were observed and fitted with a simple model. This system will allow us to study the collective magneto-optical response of materials and spatial dispersive exciton-polariton related problems in high external magnetic fields at low temperatures. (C) 2014 AIP Publishing LLC.
Low temperature and high magnetic field spectroscopic ellipsometry system
(2014-05-01)
Su, Sheng-Kai
;
Li, Liang-Chen
;
Suen, Yuen-Wuu
;
Wu, Jau-Yang
;
Kuo, Hong-Rong
We report on the design and implementation of a spectral ellipsometer at near-infrared wavelength (700-1000 nm) for samples placed in high magnetic fields (up to 14 T) at low temperatures (similar to 4.2 K). The main optical components are integrated in a probe, which can be inserted into a conventional long-neck He dewar and has a very long free-space optical path (similar to 1.8 mx2). A polarizer-sample-(quarter-wave plate)-rotating analyzer configuration was employed. Two dielectric mirrors, one before and one after the sample in the optical path, helped to reflect the light back to the analyzer and a two-axis piezo-driven goniometer under the sample holder was used to control the direction of the reflected light. Functional test results performed on an intrinsic GaAs wafer and analysis on the random error of the system are shown. We obtained both amplitude and phase ellipsometric spectra simultaneously and observed helicity transformation at energies near the GaAs exciton transitions in the phase spectra. Significant shifts of them induced by magnetic fields were observed and fitted with a simple model. This system will allow us to study the collective magneto-optical response of materials and spatial dispersive exciton-polariton related problems in high external magnetic fields at low temperatures. (C) 2014 AIP Publishing LLC.
Well-thickness dependent electron transport effective mass and mobility in Sb-based quantum wells
(2013-02-01)
Su, Sheng-Kai
;
Lee, Chien-Ping
;
Voskoboynikov, O.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We propose a special kind of Sb-based III-V semiconductor quantum wells, which, in contrary to conventional ones, are able to provide novel transport properties: smaller electron transport effective mass and higher mobility with thinner well width. By properly choosing the barrier materials with smaller electron effective mass and proper band lineups, the novel transport property could be achieved because of the penetration effect of the wave-function when interface roughness and alloy disorder scatterings are taken into consideration. (C) 2012 Elsevier B.V. All rights reserved.