Browsing by Author "Kuo, Ming-Hao"

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Characterization of carrier dynamics in Ge quantum dots through Ge quantum-dot MOSFETs using pulsed voltage technique
(2015)
Kuo, Ming-Hao
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Chen, Ho-Chane
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Lai, Wei-Ting
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Li, Pei-Wen
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電子工程學系及電子研究所
We demonstrated a novel CMOS approach for the fabrication of high-performance Ge quantum dot (QD) MOSFETs offering great promises as optical switches and transducers for Si-based optical interconnects. Measured photocurrent to dark current ratio (I-ph/I-dark) and photoresponsivities from the Ge QD PT were as high as 272,000 and 1.7 A/W, respectively, under incident power of 20 W at 980 nm illumination. Carrier dynamics in Ge QDs were characterized by applying a depleting voltage pulse to the gate of MOSFET and by time-resolved photoluminescence on Ge QD array.
Design of multifold Ge/Si/Ge composite quantum-dot heterostructures for visible to near-infrared photodetection
(2015-05-15)
Kuo, Ming-Hao
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Lai, Wei-Ting
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Lee, Sheng-Wei
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Chen, Yen-Chun
;
Chang, Chia-Wei
We demonstrate an effective approach to grow high-quality thin film (>1 mu m) ofmultifold Ge/Si/Ge composite quantum dots ( CQDs) stacked heterostructures for near infrared photodetection and optical interconnect applications. An otherwise random, self-assembly of variable-fold Ge/Si CQDs has been grown on Si through the insertion of Si spacer layers to produce micron-scale-thick, stacked Ge/Si CQD layers with desired QD morphology and composition distribution. The high crystalline quality of these multifold Ge CQD heterostructures is evidenced by low dark current density of 3.68 pA/mu m(2), superior photoresponsivity of 267 and 220 mA/W under 850 and 980 nm illumination, respectively, and very fast temporal response time of 0.24 ns measured on the Ge/Si CQD photodetectors. (C) 2015 Optical Society of America
Designer Ge Quantum-Dot Phototransistors for highly-integrated, broadband optical interconnects
(2016)
Kuo, Ming-Hao
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Chien, Chung-Yen
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Liao, Po-Hsiang
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Lai, Wei-Ting
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Li, Pei-Wen
We report high-responsivity Ge quantum dots (QDs) MOS phototransistors as on-chip transducers for highly-integrated, broadband Si-based optical interconnects. Self-organized heterostructure of Ge-QD/SiO2/Si-channel is fabricated in a single step through selective oxidation of SiGe nano-pillars over a Si3N4 buffer layer on Si substrates. Dark current densities (10(-7)A/mm(2)), photocurrent-to-dark current ratio (similar to 10(7)) and photoresponsivities (>10 A/W), external quantum efficiency (similar to 240%), and response time (1.4ns) are measured on the Ge-QD phototransistors under 850 nm illumination. Detection wavelength is tunable from near infrared to near ultraviolet by reducing the QD size from 90 to 7 nm, and the optimal photoresponsivity is tailored by the QD size and effective thickness of gate dielectrics.
High Photoresponsivity Ge-dot PhotoMOSFETs for Low-power Monolithically-Integrated Si Optical Interconnects
(2017-03-16)
Kuo, Ming-Hao
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Lee, Meng-Chun
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Lin, Horng-Chih
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George, Tom
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Li, Pei-Wen
We report the demonstration of high-photoresponsivity Ge-dot photoMOSFETs in a standard MOS configuration for the detection of 850-1550 nm illumination. Each device has a self-organized, gate-stacking heterostructure of SiO2/Ge-dot/SiO2/SiGe-channel which is simultaneously fabricated in a single oxidation step. Superior control of the geometrical size and chemical composition for our Ge nanodots/SiO2/Si1-xGex-shell MOS structure enables the practically-achievable, gate-stacking design for our Ge-dot photoMOSFETs. Both the gate oxide thickness and the diameter of the Ge dots are controllable. Large photocurrent enhancement was achieved for our Ge-dot photoMOSFETs when electrically-biased at ON-and OFF-states based on the Ge dot mediating photovoltaic and photoconductive effects, respectively. Both photoelectric conversion efficiency and response speed are significantly improved by reducing the gate-oxide thickness from 38.5 nm to 3.5 nm, and by decreasing Ge-dot size from 90 nm to 50 nm for a given areal density of Ge dots. Photoresponsivity ( R) values as high as 1.2 x 10(4) A/W and 300 A/W are measured for 10 nW illumination at 850 nm and 1550 nm, respectively. A response time of 0.48 ns and a 3 dB-frequency of 2 GHz were achieved for 50 nm-Ge-dot photoMOSFETs with channel lengths of 3 mu m under pulsed 850 nm illumination.
High Photoresponsivity Germanium Nanodot PhotoMOSFETs for Monolithically-Integrated Si Optical Interconnects
(2017-01-01)
Kuo, Ming-Hao
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Lee, Morris M.
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Li, Pei-Wen
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交大名義發表
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National Chiao Tung University
We presented a self-organized, MOS gate-stacking structure of SiO2/Ge-dot/SiO2/Si1-xGex-shell, using thermal oxidation of poly-Si0.85Ge0.15 nanopillars over buffer Si3N4 on the Si substrate, for the fabrication of high performance Ge-dot photoMOSFETs. Low dark current of 3 mu A/.m(2), Superior high photoresponsivity of 1400. 710A/W, and short response time of <0.8ns are measured on 90nm Ge-dot photoMOSFETs with W/L = 70 mu m/3 mu m under 850nm-1550nm illumination, providing a practically-achievable, core building block for monolithically-integrated Si optical interconnects.
Optimal design of Ge-dot photoMOSFETs for highly-integrated monolithic Si Photonics
(2016)
Kuo, Ming-Hao
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Lee, M. C.
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Tien, J. W.
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Lai, Wei-Ting
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Li, Pei-Wen
Ge-dot/SiO2/SiGe-channel photoMOSFETs are demonstrated on a Si-photonics platform. The photoMOSFET is fabricated in standard CMOS processes with a self-organized gate stack of Ge-dot/SiO2/SiGe-channel using thermal oxidation of SiGe nanopillars over Si3N4 layers on Si substrates. The Ge-dot photoMOSFET, with 3 mu m channel length and 70 mu m channel width, features responsivity of over 2000A/W and 100 A/W with 6pW and 0.2 mu W, respectively, under illumination at 850nm. The responsivity is further improved by reducing the dot size and increasing the spatial density and most importantly, is insensitive to the gate oxide thickness, which is a great benefit for reducing the input capacitance and thus, improving speed and power consumption.
Very large photogain and high photorespone linearity of Ge-dot photoMOSFETs operating in accumulation-mode for monolithic Si photonics
(2017-01-01)
Kuo, Ming-Hao
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Liu, B. J.
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Huang, T. L.
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Lin, H. C.
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Li, Pei-Wen
We experimentally demonstrated that the inclusion of Ge dots into the gate stack of a Si MOSFET provides extremely high photoresponsivity over 1,000A/W and superior photoresponse linearity of at least 7 decades for 400-1300nm illumination, depending on whether the Ge-dot photoMOSFET operates in the inversion or accumulation modes. Remarkably a very large photocurrent gain of 10(3)-10(8)A/A and a significantly large dynamic range of photoresponse linearity with at least 6 decades for P-IN = 6nW-1.376mW are concurrently achievable for our Ge-dot photoMOSFETs in the accumulation-mode operation thanks to extremely low dark current of 40pA. Photocarrier generation and recombination under high power illumination is analytically simulated.
Very large photoresponsiviy and high photocurrent linearity for Ge-dot/SiO2/SiGe photoMOSFETs under gate modulation
(2017-10-16)
Kuo, Ming-Hao
;
Hong, Po-Yu
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Liu, Ping-Che
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Lee, Meng-Chun
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Lin, Horng-Chih
We report a novel visible-near infrared photoMOSFET containing a self-organized, gate-stacking heterostructure of SiO2/Ge-dot/SiO2/SiGe-channel on Si substrate that is simultaneously fabricated in a single oxidation step. Our typical photoMOSFETs exhibit very large photoresponsivity of 1000-3000A/W at low optical power (< 0.1 mu W) or large photocurrent gain of 10(3)-10(8)A/A with a wide dynamic power range of at least 6 orders of magnitude (nW-mW) linearity at 400-1250 nm illumination, depending on whether the photoMOSFET operates at V-G = + 3- + 4.5V or -1- + 1V. Numerical simulations reveal that photocarrier confinement within the Ge dots and the SiGe channel modifies the oxide field and the surface potential of SiGe, significantly increasing photocurrent and improving linearity. (C) 2017 Optical Society of America