Browsing by Author "Peng, K. P."

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Counter-intuitive Ge/Si/O interactions and Ge/Si symbiosis enable the creatation of new classes of exciting nanoelectronic and nanophotonic devices
(2017-01-01)
Hsueh, C. Y.
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Huang, T. L.
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Peng, K. P.
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Kuo, M. H.
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Lin, H. C.
We have successfully exploited multi-dimensional spaces of concentrations of the interstitial species, Si and Ge, geometries and compositions of the starting SiGe nano-pillar, and sources of Si interstitials (the Si3N4 and Si encapsulation layers) to create new classes of exciting optical and electronic devices such as single-electron tunneling devices, wavelength tunable photodetectors, and MOSFETs.
Single-fabrication-step Ge nanosphere/SiO2/SiGe heterostructures: a key enabler for realizing Ge MOS devices
(2018-05-18)
Liao, P. H.
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Peng, K. P.
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Lin, H. C.
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George, T.
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Li, P. W.
We report channel and strain engineering of self-organized, gate-stacking heterostructures comprising Ge-nanosphere gate/SiO2/SiGe-channels. An exquisitely-controlled dynamic balance between the concentrations of oxygen, Si, and Ge interstitials was effectively exploited to simultaneously create these heterostructures in a single oxidation step. Process-controlled tunability of the channel length (5-95 nm diameters for the Ge-nanospheres), gate oxide thickness (2.5-4.8 nm), as well as crystal orientation, chemical composition and strain engineering of the SiGe-channel was achieved. Single-crystalline (100) Si1-xGex shells with Ge content as high as x = 0.85 and with a compressive strain of 3%, as well as (110) Si1-xGex shells with Ge content of x = 0.35 and corresponding compressive strain of 1.5% were achieved. For each crystal orientation, our high Ge-content, highly-stressed SiGe shells feature a high degree of crystallinity and thus, provide a core 'building block' required for the fabrication of Ge-based MOS devices.
'Symbiotic' semiconductors: unusual and counter-intuitive Ge/Si/O interactions
(2017-03-15)
George, T.
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Li, P. W.
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Chen, K. H.
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Peng, K. P.
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Lai, W. T.
Since the inception of the first transistors in the 1940s, the immense body of work on the Group IV semiconductors, Si and Ge, has spearheaded spectacular advances in modern integrated-circuit (IC) technology that has enabled a vast landscape of device applications in logic, memory, and computing. Although initially Si supplanted Ge as the material of choice for metal-oxide-semiconductor field-effect transistors, Ge-based devices are now breaking new ground. Widespread and innovative Ge-based applications exist in optoelectronics, communications, microelectro-mechanical systems, and energy harvesting/savings. On the fundamental, materials science front, while it is well known that Ge and Si are fully miscible in each other, the nature and extent of their attraction for each other has largely been unexplored. In this paper, we report a rather curious interplay between Ge and Si that occurs at high temperature (similar to 900 degrees C) and that can be best described as 'symbiotic'. Each element appears to facilitate reactions in the other which would otherwise not be possible. Oxygen intersititials also appear to play a major role in these reactions. Our experimental work has allowed us to classify four distinct regimes where these reactions occur. We describe these conditions and provide the necessary theoretical explanations for these results.
Tunable Ge content and thickness in hemispherical-shell shaped SiGe recess channels created by proximal Ge nanospheres
(2019-05-01)
Chen, C. T.
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Peng, K. P.
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George, T.
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Lin, H. C.
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Li, Pei-Wen
We report the novel tunability of Ge content, thickness, and even curvature/shape in self-aligned, hemispherical-shell shaped SiGe recess channels created in Si substrates by Ge nanospheres that are proximally located to these nanoshells. The hemispherical recess SiGe nanoshells arise from the migration of Ge interstitials through the intervening oxide layer between the Ge nanospheres and the Si substrate, and their Ge content, thickness, and curvatures exhibit a monotonic dependence on the depth of penetration of the Ge nanospheres into the Si substrate. Following a unique "explosion" phenomenon in which the Ge nanosphere breaks up into multiple nanocrystallites, both the Ge content and thickness of the SiGe nanoshells are significantly decreased by reverse migration of Ge interstitials from the SiGe nanoshells to the Ge nanocrystallites. (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/).