The emerging Au-assisted exfoliation technique provides a wealth of large-area and high-quality ultrathin two-dimensional (2D) materials compared with traditional tape-based exfoliation. Fast, damage-free, and reliabl...
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The morphology of the in-situ etching process on Si-face and C-face 4H-SiC, by annealing in a hydrogen environment, is studied by atomic force microscopy (AFM). The uniform step-terrace morphology of both the Si-face ...
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The effects of annealing on epitaxial graphene on SiC substrates with various conditions are investigated. Results show that high pressure hydrogen atmosphere is more effective to decouple the epitaxial graphene from ...
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In this work, we demonstrate heterogeneous integration of InP DHBT and Si CMOS on the same Silicon substrate based on 30μm Au-In microbump bonding technology, InP DHBTs are vertical stacked at the top of the Si CMOS ...
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In this work, we demonstrate heterogeneous integration of InP DHBT and Si CMOS on the same Silicon substrate based on 30μm Au-In microbump bonding technology, InP DHBTs are vertical stacked at the top of the Si CMOS wafer. Meanwhile, we exhibit a InP-on-Si CMOS 14Gbps 1:16 demultiplexer as example, which shows the potential to integrate InP and Si CMOS on the same chip to take advance of the two different material systems.
GaAs terahertz schottky barrier diode SBD has been a major technology in terahertz wave multiplexing, mixing and direct detection for decades, due to its high mobility and low capacity. In this paper, T-anode GaAs ter...
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ISBN:
(数字)9781728190648
ISBN:
(纸本)9781728190655
GaAs terahertz schottky barrier diode SBD has been a major technology in terahertz wave multiplexing, mixing and direct detection for decades, due to its high mobility and low capacity. In this paper, T-anode GaAs terahertz SBD was presented with its C j0 scaled into sub-fF range. Scalling C-V measurement showed C j0 without parasitic capacity reached 0.476fF for the 0.5μm anode diameter device. With the relative low series resistance R s of 28.8Ω, cutoff frequency f t reached 11.6THz. The whole process was based on 4 inch GaAs wafer, guarantee stability and conformity in terahertz GaAs SBD integratedcircuits working over 1THz.
Thermal transport properties of GaN heteroepitaxial structures are of critical importance for the thermal management of high-power GaN electronic and optoelectronic devices. Ultraviolet(UV) lasers are employed to dire...
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Thermal transport properties of GaN heteroepitaxial structures are of critical importance for the thermal management of high-power GaN electronic and optoelectronic devices. Ultraviolet(UV) lasers are employed to directly heat and sense the GaN epilayers in the transient thermoreflectance(TTR) measurement, obtaining important thermal transport properties in different GaN heterostructures, which include a diamond thin film heat spreader grown on GaN. The UV TTR technique enables rapid and non-contact thermal characterization for GaN wafers.
By designing and fabricating a series of dual-interferometer coupled silicon microrings, the coupling condition of the pump, signal, and idler beams can be engineered independently and then we carried out both the con...
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By designing and fabricating a series of dual-interferometer coupled silicon microrings, the coupling condition of the pump, signal, and idler beams can be engineered independently and then we carried out both the continuous-wave and pulse pumped four-wave mixing experiments to verify the dependence of conversion efficiency on the coupling conditions of the four interacting beams, respectively. Under the continuous-wave pump, the four-wave mixing efficiency gets maximized when both the pump and signal/idler beams are closely operated at the critical coupling point, while for the pulse pump case, the efficiency can be enhanced greatly when the pump and converted idler beams are all overcoupled. These experiment results agree well with our theoretical calculations. Our design provides a platform for explicitly characterizing the four-wave mixing under different pumping conditions, and offers a method to optimize the four-wave mixing, which will facilitate the development of on-chip all-optical signal processing with a higher efficiency or reduced pump power.
The microfluid cooling is widely used in the thermal management for high power integration in 3D Si RF microsystem. The simple and efficient microfluid structure is essential in large area cooling for the module with ...
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ISBN:
(数字)9781728168265
ISBN:
(纸本)9781728168272
The microfluid cooling is widely used in the thermal management for high power integration in 3D Si RF microsystem. The simple and efficient microfluid structure is essential in large area cooling for the module with multiple active devices integrated on silicon. A novel Laval microchannel structure was proposed in this paper, and it was simple to design and easy for process. The thermal and hydraulic characteristics of Laval microchannel were investigated and compared with the conventional straight microchannel and 2 kinds of common serpentine microchannels using FEM analysis. The results indicated that Laval microchannel had low flow resistance to maintain high pumping power and achieved the best cooling performance among different microchannel structures. And Laval structure can be effective to keep junction temperature below 150 °C which can provide the sufficient condition for GaN HEMTs device operating with high efficiency and good linearity. It presented remarkable cooling performance for GaN HEMTs cooling integrated on Si, showing excellent candidate structure for large area cooling in 3D Si RF microsystem.
An analysis on the heat transfer feature of the microfluid cooling based on the microjet structure in the Si interposer for GaN HEMTs was investigated to meet the requirement of thermal management in RF microsystem in...
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ISBN:
(数字)9781728168265
ISBN:
(纸本)9781728168272
An analysis on the heat transfer feature of the microfluid cooling based on the microjet structure in the Si interposer for GaN HEMTs was investigated to meet the requirement of thermal management in RF microsystem integration. The microjet cooling structure in the Si interposer consists of 2 layers of microfluids forming the microjets in the bottom layer and separating in the top layer from 2 directions. The GaN HEMTs device is bonded on the Si interposer with the transistor gates above the microjets to utilize the high local heat transfer coefficient effectively. The distributions of temperature and the maximum pressure variations in the cooling structure with different size parameters at different flow rates were investigated using FEM analysis, and the optimum relations of dominant parameters were proposed to achieve excellent cooling performance in this paper. Therefore, a simplified function can be established to evaluate the heat transfer coefficient with the optimized size parameters. The model of a 48 W/mm 2 power density GaN HEMTs device integrated on the Si interposer with optimized microjet cooling structure was simulated. The result indicated that the thermal resistance of the integrated system is 0.96 K/W which is equal to the thermal resistance of the device bonded on a 3 mm thick copper plate directly. The study on the property of the microfluid cooling in Si interposer provided a useful support for RF microsystem heterogeneous integration for GaN high power device on silicon.
One of the most challenging problems that limit the practical application of carbon-based photothermal nanofluids is their poor dispersion stability and tendency to form aggregation. Herein, by using Fe3O4@graphene hy...
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One of the most challenging problems that limit the practical application of carbon-based photothermal nanofluids is their poor dispersion stability and tendency to form aggregation. Herein, by using Fe3O4@graphene hybrid nanoparticles as a model system, we proposed a new method to prepare stably dispersed silicone oilbased solar-thermal nanofluids that can operate at high temperatures than water-based fluids. The introduction of Fe3O4nanoparticles between graphene nanosheets not only physically increases the inter-plane distance of the graphene nanosheet but also provides numerous anchoring points for surface modification. Phosphate-terminated polydimethylsiloxane chains, which have high compatibility with the silicone oil base fluids and hightemperature stability, were synthesized and utilized to modify the Fe3O4nanoparticle surfaces. The attached chains create steric hindrance and effectively screen the strong inter-plane van der Waals attraction between graphene sheets. Dispersion stability of the nanofluids with different concentrations of surface-modified hybrid nanoparticles and heated under different temperatures was investigated. We have demonstrated that such fluids could maintain stable dispersion under a heating temperature up to 150 °C depending on the concentration of the hybrid nanoparticles. The resultant nanofluids maintained stable dispersion after repeated heating and were employed for consistent direct solar-thermal energy harvesting at 100 °C.
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