🏛️國立陽明交通大學機構典藏

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Bidirectional All-Optical Synapses Based on a 2D Bi2O2Se/Graphene Hybrid Structure for Multifunctional Optoelectronics
(1970-01-01)
Yang, Chia-Ming
;
Chen, Tsung-Cheng
;
Verma, Dharmendra
;
Li, Lain-Jong
;
Liu, Bo
Neuromorphic computing has been extensively studied to mimic the brain functions of perception, learning, and memory because it may overcome the von Neumann bottleneck. Here, with the light-induced bidirectional photoresponse of the proposed Bi2O2Se/graphene hybrid structure, its potential use in next-generation neuromorphic hardware is examined with three distinct optoelectronic applications. First, a photodetector based on a Bi2O2Se/graphene hybrid structure presents positive and negative photoresponsibility of 88 and -110 A W-1 achieved by the excitation of visible wavelength and ultraviolet wavelength light at intensities of 1.2 and 0.3 mW cm(-2), respectively. Second, this unique photoresponse contributes to the realization of all optically stimulated long-term potentiation or long-term depression to mimic synaptic short-term plasticity and long-term plasticity, which are attributed to the combined effect of photoconductivity, bolometric, and photoinduced desorption. Third, the devices are applied to perform digital logic functions, such as "AND" and "OR," using full light modulation. The proposed Bi2O2Se/graphene-based optoelectronic device represents an innovative and efficient building block for the development of future multifunctional artificial neuromorphic systems.
Efficient Heat Dissipation of Photonic Crystal Microcavity by Mono layer Graphene
(2013-12-01)
Shih, Min-Hsiung
;
Li, Lain-Jong
;
Yang, Yi-Chun
;
Chou, Hsiang-Yu
;
Lin, Cheng-Te
Graphene, which exhibits excellent thermal conductivity, is a potential heat dissipation medium for compact optoelectronic devices. Photonic devices normally produce large-quantity of unwanted heat, and thus, a heat dissipation strategy is urgently needed. In this study, single-layer graphene (SLG) grown by chemical vapor deposition (CVD) is used to cover the surface of a photonic crystal (PhC) cavity, where the heat flux produced by the PhC cavity can be efficiently dissipated along the in-plane direction of the SLG. The thermal properties of the graphene-capped PhC cavity were characterized by experiments and theoretical calculations. The thermal resistance of the SLG-capped PhC cavity obtained from experiments is lower than half of that of a bare PhC cavity. The temperature of a SLG-capped PhC cavity is 45 K lower than that without SLG capping under an optical power of 100 mu W. Our simulation results indicate that SLG receives the majority of the heat fluxes from the device, leading to the efficient heat dissipation. Both the experimental and simulation results suggest that the SLG is a promising material to enhance the heat dissipation efficiency for optoelectronic applications.
Few-Layer MoS2 with High Broadband Photogain and Fast Optical Switching for Use in Harsh Environments
(2013-05-01)
Tsai, Dung-Sheng
;
Liu, Keng-Ku
;
Lien, Der-Hsien
;
Tsai, Meng-Lin
;
Kang, Chen-Fang
Few-layered MoS2 as Schottky metal-semiconductor-metal photodetectors (MSM PDs) for use In harsh environments makes its debut as two-dimensional (2D) optoelectronics with high broadband gain (up to 13.3), high detectivity (up to similar to 10(10) cm Hz(1/2)/W), fast photoresponse (rise time of similar to 70 mu s and fall time of similar to 110 mu s), and high thermal stability (at a working temperature of up to 200 degrees C). Ultrahigh responsivity (0.57 A/W) of few-layer MoS2 at 532 nm is due to the high optical absorption (similar to 10% despite being less than 2 nm in thickness) and a high photogain, which sets up a new record that was not achievable in 2D nanomaterials previously. This study opens avenues to develop 2D nanomaterial-based optoelectronics for harsh environments in imaging techniques and light-wave communications as well as in future memory storage and optoelectronic circuits.
Label-Free Electrical Detection of DNA Hybridization on Graphene using Hall Effect Measurements: Revisiting the Sensing Mechanism
(2013-05-13)
Lin, Cheng-Te
;
Phan Thi Kim Loan
;
Chen, Tzu-Yin
;
Liu, Keng-Ku
;
Chen, Chang-Hsiao
There is broad interest in using graphene or graphene oxide sheets as a transducer for label-free and selective electrical detection of biomolecules such as DNA. However, it is still not well explored how the DNA molecules interact with and influence the properties of graphene during the detection. Here, Hall effect measurements based on the Van der Pauw method are used to perform single-base sequence selective detection of DNA on graphene sheets, which are prepared by chemical vapor deposition. The sheet resistance increases and the mobility decreases with the addition of either complementary or one-base mismatched DNA to the graphene device. The hole carrier concentration of the graphene devices increases significantly with the addition of complementary DNA but it is less affected by the one-base mismatched DNA. It is concluded that the increase in hole carrier density, indicating p-doping to graphene, is better correlated with the DNA hybridization compared to the commonly used parameters such as conductivity change. The different electrical observations of p-doping from Hall effect measurements and n-doping from electrolyte-gated transistors can be explained by the characteristic morphology of partially hybridized DNA on graphene and the mismatch between DNA chain length and Debye length in electrolytes.
Electrical Probing of Submicroliter Liquid Using Graphene Strip Transistors Built on a Nanopipette
(2012-01-09)
Chen, Chang-Hsiao
;
Lin, Cheng-Te
;
Lee, Yi-Hsien
;
Liu, Keng-Ku
;
Su, Ching-Yuan

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