| 1. |
- Li, J., et al.
(författare)
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Study of selective isotropic etching Si1−xGex in process of nanowire transistors
- 2020
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Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 31:1, s. 134-143
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Tidskriftsartikel (refereegranskat)abstract
- On approach towards the end of technology roadmap, a revolutionary approach towards the nanowire transistors is favorable due to the full control of carrier transport. The transistor design moves toward vertically or laterally stacked Gate-All-Around (GAA) where Si or SiGe can be used as channel material. This study presents a novel isotropic inductively coupled plasma (ICP) dry etching of Si1−xGex (0.10 ≤ x ≤ 0.28) in SiGe/Si multilayer structures (MLSs) with high selectivity to Si, SiO2, Si3N4 and SiON which can be applied in advanced 3D transistors and Micro-Electro-Mechanical System (MEMS) in future. The profile of SiGe etching for different thicknesses, compositions and locations in MLSs using dry or wet etch have been studied. A special care has been spent for layer quality of Si, strain relaxation of SiGe layers as well as residual contamination during the etching. In difference with dry etching methods (downstream remote plasma), the conventional ICP source in situ is used where CF4/O2/He gas mixture was used as the etching gas to obtain higher selectivity. Based on the reliability of ICP technique a range of etching rate 25–50 nm/min can be obtained for accurate isotropic etching of Si1−xGex, to form cavity in advanced 3D transistor processes in future.
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| 2. |
- Zhu, Youjian, et al.
(författare)
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Ash Fusion Characteristics and Transformation Behaviors during Bamboo Combustion in Comparison with Straw and Poplar
- 2018
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:4, s. 5244-5251
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the bamboo ash fusion and sintering characteristics were studied to evaluate its potential application in combustion for the production of heat and power. Poplar and wheat straw were used in the experimental test as the reference fuels for comparison. Standard ash fusion tests and ash sintering tests were carried out at elevated temperatures. The results indicate that bamboo has a low ash melting temperature of 862 °C, much lower than that of poplar. In spite of the high K content in bamboo ash, no severe melting and sintering was observed under the temperature lower than 1000 °C. The ashes after the tests were analyzed using SEM/EDX, XRF, and XRD techniques to illustrate the ash transformation behavior. Standard ash fusion tests indicated that the melting temperatures of bamboo, wheat straw, and poplar ashes are 862 °C, 770 °C, and 1088 °C, respectively. No severe sintering can be observed for poplar due to the large existence of refractory compounds. Ash sintering occurred when the temperature is higher than 800 °C, for wheat straw, due to the formation of the low melting temperature K-rich silicate. Additionally, bamboo ash has a relatively high P content compared to that of wheat straw, which facilitates the formation of high melting temperature compounds of K-Ca/Mg phosphates. Moreover, the ash content in bamboo is low. As a conclusion, bamboo is a good quality biofuel which can be fired in biomass combustion plants without severe sintering at a temperature lower than 1000 °C.
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| 3. |
- Zhu, Youjian, et al.
(författare)
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Reduction of fine particulate matter emissions from cornstalk combustion by calcium phosphates additives
- 2021
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 283
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Tidskriftsartikel (refereegranskat)abstract
- The emission of fine particulate matters with an aerodynamic diameter of less than 1 µm (PM1) is usually high from straw biomass combustion, resulting in great danger to atmospheric environment and public health. In this work, the effect of three calcium phosphate additives on PM1 emission from cornstalk combustion was investigated using a lab-scale reactor. The addition of Ca(H2PO4)2, CaHPO4 and Ca3(PO4)2 reduced PM1 emission by 1.5–50.6%, 22–55.6% and 23–53.7%, respectively. For Ca(H2PO4)2, PM1 reduction rate reached its maximum values of 50.6% at P/K molar ratio equal to 1 and then decreased significantly with further increasing of P/K molar ratio. For both CaHPO4 and Ca3(PO4)2, PM1 reduction rate increased approximately linearly with increasing the amount of additives under the current operating conditions. Analyses of the collected particulate matters and residual ashes indicated that phosphorus was mainly transformed into PM1-10 and residual ash in the form of K-Ca/Mg phosphates and Ca/Mg phosphates, respectively. The PM1 reduction mechanism was proposed based on the characterization results. Finally, economic analysis showed that the addition of Ca3(PO4)2 is a potentially promising method to reduce PM1 emissions during straw biomass combustion.
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