| 1. |
- Akbari-Saatlu, Mehdi, et al.
(författare)
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Silicon Nanowires for Gas Sensing : A Review
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:11
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Forskningsöversikt (refereegranskat)abstract
- The unique electronic properties of semiconductor nanowires, in particular silicon nanowires (SiNWs), are attractive for the label-free, real-time, and sensitive detection of various gases. Therefore, over the past two decades, extensive efforts have been made to study the gas sensing function of NWs. This review article presents the recent developments related to the applications of SiNWs for gas sensing. The content begins with the two basic synthesis approaches (top-down and bottom-up) whereby the advantages and disadvantages of each approach have been discussed. Afterwards, the basic sensing mechanism of SiNWs for both resistor and field effect transistor designs have been briefly described whereby the sensitivity and selectivity to gases after different functionalization methods have been further presented. In the final words, the challenges and future opportunities of SiNWs for gas sensing have been discussed.
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| 2. |
- Du, Yong, et al.
(författare)
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Investigation of the Heteroepitaxial Process Optimization of Ge Layers on Si (001) by RPCVD
- 2021
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- This work presents the growth of high-quality Ge epilayers on Si (001) substrates using a reduced pressure chemical vapor deposition (RPCVD) chamber. Based on the initial nucleation, a low temperature high temperature (LT-HT) two-step approach, we systematically investigate the nucleation time and surface topography, influence of a LT-Ge buffer layer thickness, a HT-Ge growth temperature, layer thickness, and high temperature thermal treatment on the morphological and crystalline quality of the Ge epilayers. It is also a unique study in the initial growth of Ge epitaxy; the start point of the experiments includes Stranski-Krastanov mode in which the Ge wet layer is initially formed and later the growth is developed to form nuclides. Afterwards, a two-dimensional Ge layer is formed from the coalescing of the nuclides. The evolution of the strain from the beginning stage of the growth up to the full Ge layer has been investigated. Material characterization results show that Ge epilayer with 400 nm LT-Ge buffer layer features at least the root mean square (RMS) value and it's threading dislocation density (TDD) decreases by a factor of 2. In view of the 400 nm LT-Ge buffer layer, the 1000 nm Ge epilayer with HT-Ge growth temperature of 650 degrees C showed the best material quality, which is conducive to the merging of the crystals into a connected structure eventually forming a continuous and two-dimensional film. After increasing the thickness of Ge layer from 900 nm to 2000 nm, Ge surface roughness decreased first and then increased slowly (the RMS value for 1400 nm Ge layer was 0.81 nm). Finally, a high-temperature annealing process was carried out and high-quality Ge layer was obtained (TDD=2.78 x 10(7) cm(-2)). In addition, room temperature strong photoluminescence (PL) peak intensity and narrow full width at half maximum (11 meV) spectra further confirm the high crystalline quality of the Ge layer manufactured by this optimized process. This work highlights the inducing, increasing, and relaxing of the strain in the Ge buffer and the signature of the defect formation.
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| 3. |
- Du, Yong, et al.
(författare)
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Review of Highly Mismatched III-V Heteroepitaxy Growth on (001) Silicon
- 2022
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 12:5
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Forskningsöversikt (refereegranskat)abstract
- Si-based group III-V material enables a multitude of applications and functionalities of the novel optoelectronic integration chips (OEICs) owing to their excellent optoelectronic properties and compatibility with the mature Si CMOS process technology. To achieve high performance OEICs, the crystal quality of the group III-V epitaxial layer plays an extremely vital role. However, there are several challenges for high quality group III-V material growth on Si, such as a large lattice mismatch, highly thermal expansion coefficient difference, and huge dissimilarity between group III-V material and Si, which inevitably leads to the formation of high threading dislocation densities (TDDs) and anti-phase boundaries (APBs). In view of the above-mentioned growth problems, this review details the defects formation and defects suppression methods to grow III-V materials on Si substrate (such as GaAs and InP), so as to give readers a full understanding on the group III-V hetero-epitaxial growth on Si substrates. Based on the previous literature investigation, two main concepts (global growth and selective epitaxial growth (SEG)) were proposed. Besides, we highlight the advanced technologies, such as the miscut substrate, multi-type buffer layer, strain superlattice (SLs), and epitaxial lateral overgrowth (ELO), to decrease the TDDs and APBs. To achieve high performance OEICs, the growth strategy and development trend for group III-V material on Si platform were also emphasized.
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| 4. |
- Kolahdouz, Mohammadreza, et al.
(författare)
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Carbon-Related Materials : Graphene and Carbon Nanotubes in Semiconductor Applications and Design
- 2022
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 13:8
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Forskningsöversikt (refereegranskat)abstract
- As the scaling technology in the silicon-based semiconductor industry is approaching physical limits, it is necessary to search for proper materials to be utilized as alternatives for nanoscale devices and technologies. On the other hand, carbon-related nanomaterials have attracted so much attention from a vast variety of research and industry groups due to the outstanding electrical, optical, mechanical and thermal characteristics. Such materials have been used in a variety of devices in microelectronics. In particular, graphene and carbon nanotubes are extraordinarily favorable substances in the literature. Hence, investigation of carbon-related nanomaterials and nanostructures in different ranges of applications in science, technology and engineering is mandatory. This paper reviews the basics, advantages, drawbacks and investigates the recent progress and advances of such materials in micro and nanoelectronics, optoelectronics and biotechnology.
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| 5. |
- Radamson, Henry H., et al.
(författare)
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State of the Art and Future Perspectives in Advanced CMOS Technology
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:8
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Forskningsöversikt (refereegranskat)abstract
- The international technology roadmap of semiconductors (ITRS) is approaching the historical end point and we observe that the semiconductor industry is driving complementary metal oxide semiconductor (CMOS) further towards unknown zones. Today's transistors with 3D structure and integrated advanced strain engineering differ radically from the original planar 2D ones due to the scaling down of the gate and source/drain regions according to Moore's law. This article presents a review of new architectures, simulation methods, and process technology for nano-scale transistors on the approach to the end of ITRS technology. The discussions cover innovative methods, challenges and difficulties in device processing, as well as new metrology techniques that may appear in the near future.
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| 6. |
- Xu, Buqing, et al.
(författare)
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Compound-Specific Radiocarbon Analysis of Low Molecular Weight Dicarboxylic Acids in Ambient Aerosols Using Preparative Gas Chromatography : Method Development
- 2021
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Ingår i: Environmental Science and Technology Letters. - : American Chemical Society (ACS). - 2328-8930. ; 8:2, s. 135-141
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Tidskriftsartikel (refereegranskat)abstract
- Low molecular weight dicarboxylic acids constitute a large fraction of atmospheric organic aerosols, which impact atmospheric radiative forcing and hence Earth's climate. Radiocarbon (C-14) is a unique approach to unambiguously distinguishing the relative contributions of biomass-derived and fossil sources. Here, we developed a compound-specific radiocarbon analysis (CSRA) method for individual dicarboxylic acids in atmospheric particulates. Specifically, the method starts with a dibutyl ester derivatization technique, followed by separation and harvesting of single compounds employing AIMS a preparative capillary gas chromatography in sufficient amounts for offline C-14 measurement with accelerator mass spectrometry. The optimized preparative steps yielded recoveries of >60% and purities of >99% for target molecules. The radiocarbon isotope compositions determined for reference standards taken through the entire method agree well with the original composition of each standard (R-2 = 0.9998). The applicability of the approach was demonstrated with ambient aerosol samples representing contrasting air mass regimes. This yielded two radically different yet system-consistent precursor sources. A minimum size of 50 mu g of C of ambient dicarboxylic acids is needed for credible C-14 measurement. The established method for CSRA of dicarboxylic acids demonstrates a new analytical dimension for studies of the source and evolution of atmospheric secondary organic aerosols.
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| 7. |
- Xu, Buqing, et al.
(författare)
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Large contribution of fossil-derived components to aqueous secondary organic aerosols in China
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Incomplete understanding of the sources of secondary organic aerosol (SOA) leads to large uncertainty in both air quality management and in climate change assessment. Chemical reactions occurring in the atmospheric aqueous phase represent an important source of SOA mass, yet, the effects of anthropogenic emissions on the aqueous SOA (aqSOA) are not well constrained. Here we use compound-specific dual-carbon isotopic fingerprints (δ13C and Δ14C) of dominant aqSOA molecules, such as oxalic acid, to track the precursor sources and formation mechanisms of aqSOA. Substantial stable carbon isotope fractionation of aqSOA molecules provides robust evidence for extensive aqueous-phase processing. Contrary to the paradigm that these aqSOA compounds are largely biogenic, radiocarbon-based source apportionments show that fossil precursors produced over one-half of the aqSOA molecules. Large fractions of fossil-derived aqSOA contribute substantially to the total water-soluble organic aerosol load and hence impact projections of both air quality and anthropogenic radiative forcing. Our findings reveal the importance of fossil emissions for aqSOA with effects on climate and air quality.
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