Browsing by Author "Wu, Jenq-Shinn"

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Antimonidation of ultrathin epitaxial aluminum nanofilms for metamorphic growth of Sb-based structures on GaAs substrates
(2020-04-01)
Wu, Yu-Hsun
;
Wu, Jenq-Shinn
;
Lin, Sheng-Di
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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
The narrow-bandgap Sb-based semiconductors find their potential in various kinds of device applications such as high-speed, low-power transistors and mid-infrared diode lasers. However, epitaxial growth on the substrates that are commercially available in large sizes (for example, GaAs and Si) faces the fundamental challenge of lattice mismatch. Different from the conventional metamorphic growth employing a thick buffer, we adopt the approach of transforming an ultrathin epitaxial aluminum (Al) nanofilm into epitaxial AlSb to serve as the template for growth of antimonide structures. It is found that the process named "antimonidation" plays a critical role in Sb-based metamorphic growth. Our experimental results provide practical usefulness for growing semiconductor devices on lattice-mismatched substrates without using thick metamorphic buffer layers. (C) 2020 The Japan Society of Applied Physics
Atomic-scale epitaxial aluminum film on GaAs substrate
(2017-07-01)
Fan, Yen-Ting
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Lo, Ming-Cheng
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Wu, Chu-Chun
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Chen, Peng-Yu
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Wu, Jenq-Shinn
Atomic-scale metal films exhibit intriguing size-dependent film stability, electrical conductivity, superconductivity, and chemical reactivity. With advancing methods for preparing ultra-thin and atomically smooth metal films, clear evidences of the quantum size effect have been experimentally collected in the past two decades. However, with the problems of small-area fabrication, film oxidation in air, and highly-sensitive interfaces between the metal, substrate, and capping layer, the uses of the quantized metallic films for further ex-situ investigations and applications have been seriously limited. To this end, we develop a large-area fabrication method for continuous atomic-scale aluminum film. The self-limited oxidation of aluminum protects and quantizes the metallic film and enables ex-situ characterizations and device processing in air. Structure analysis and electrical measurements on the prepared films imply the quantum size effect in the atomic-scale aluminum film. Our work opens the way for further physics studies and device applications using the quantized electronic states in metals. (C) 2017 Author(s).
Epitaxial GaAs and pHEMT on aluminum-transformed AlAs nanofilms
(2018-09-01)
Cheng, Chia-Chu
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Wu, Chu-Chun
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Fan, Yen-Ting
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Wu, Jenq-Shinn
;
Lin, Sheng-Di
Heterogeneous epitaxial growth between semiconductors and metals boosts novel device development and enables various applications. In this work, we have investigated the epitaxial growth of GaAs layers on top of a nanoscale aluminium-transformed AlAs film. The grown GaAs layers are single-crystalline and of highquality, that has been evidenced by using various material characterization methods and by fabricating their high-electron mobility transistors. We found that an intriguing process named as "arsenidation" of aluminium film plays a key role in the successful epitaxy. Our work opens a window for growing semiconductor/metal hetero-structures for various device applications in the future. (C) 2018 Author(s).
High-sensitivity two-terminal magnetoresistance devices using InGaAs/AlGaAs two-dimensional channel on GaAs substrate
(2016-04-25)
Wu, Di-Cheng
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Pan, You-Wei
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Wu, Jenq-Shinn
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Lin, Shih-Wei
;
Lin, Sheng-Di
We demonstrate experimentally the two-terminal magnetic sensors exhibiting an extraordinary magneto-resistance effect by using an InGaAs quantum well channel with a metal-shunting structure. A high magneto-resistance of 17.3% and a sensitivity of 488.1 Omega/T have been obtained at 1 T and room temperature with our geometrical design. The two-contact configuration and the high-mobility electron transistor-compatible epitaxy structure make the devices promising for high-sensitivity magnetic sensing integration and applications. Published by AIP Publishing.
Nano- to atomic-scale epitaxial aluminum films on Si substrate grown by molecular beam epitaxy
(2019-10-01)
Tsai, Yi-Hsun
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Wu, Yu-Hsun
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Ting, Yen-Yu
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Wu, Chu-Chun
;
Wu, Jenq-Shinn
We demonstrate nano-to atomic-scale epitaxial aluminum film growth on Si(111) substrate by molecular beam epitaxy. Excellent quality of these aluminum films, including sub-nanometer surface roughness, narrow linewidth of X-ray diffraction peak, clear transmission electron diffraction, and high optical reflectivity in ultra-violet, have been obtained with a reproducible growth recipe. The atomic-scale metallic aluminum film is formed by the self-limiting oxidation on the 3-nm-thick sample in air and the metallic state is confirmed with X-ray photoemission spectroscopy. Our work paves the way to future integration of aluminum-based plasmonic and superconducting devices on Si platform. (c) 2019 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Optical and Electrical Characterizations of ZnMnO Thin Films on c-Al(2)O(3)
(2009-04-01)
Lin, Hung-Ji
;
Lin, Der-Yuh
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Wu, Jenq-Shinn
;
Yang, Chu-Shou
;
Chou, Wu-Ching
We have studied the manganese (Mn) composition dependence of the optical and electrical properties of ZnMnO thin films, which are grown on c-Al(2)O(3) substrates by plasma-assisted molecular beam epitaxy (PAMBE). The lattice constant and grain size are estimated by Xray diffraction (XRD), and it is found that the lattice constant increases and the grain size decreases with increasing Mn composition. When more Mn is incorporated into the ZnMnO thin films, a blue shift of the absorption edges and photoluminescence emission peaks are observed. Hall measurement shows n-type conduction behavior for all the samples. The decrease in mobility might be related with the increase in the number of impurity scattering centers, and the decrease in the carrier concentration can be attributed to the carrier quenching effect induced by the deep-level defects. The ac electrical response of ZnMnO is studied by impedance spectroscopy (IS). The equivalent RC circuit and parameters of the grain and grain boundary are determined. (C) 2009 The Japan Society of Applied Physics
Optical and Electrical Characterizations of ZnMnO Thin Films on c-Al2O3
(2009-04-01)
Lin, Hung-Ji
;
Lin, Der-Yuh
;
Wu, Jenq-Shinn
;
Yang, Chu-Shou
;
Chou, Wu-Ching
We have studied the manganese (Mn) composition dependence of the optical and electrical properties of ZnMnO thin films, which are grown on c-Al2O3 substrates by plasma-assisted molecular beam epitaxy (PAMBE). The lattice constant and grain size are estimated by Xray diffraction (XRD), and it is found that the lattice constant increases and the grain size decreases with increasing Mn composition. When more Mn is incorporated into the ZnMnO thin films, a blue shift of the absorption edges and photoluminescence emission peaks are observed. Hall measurement shows n-type conduction behavior for all the samples. The decrease in mobility might be related with the increase in the number of impurity scattering centers, and the decrease in the carrier concentration can be attributed to the carrier quenching effect induced by the deep-level defects. The ac electrical response of ZnMnO is studied by impedance spectroscopy (IS). The equivalent RC circuit and parameters of the grain and grain boundary are determined. (C) 2009 The Japan Society of Applied Physics