Adsorption structures of the 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) molecule on the clean Si(001) - 2 × 1 surface were investigated using scanning tunneling microscopy (STM) experiments in conjunction with first principles theoretical calculations. Four dominant adsorption structures were observed in the STM experiments and their atomic coordinates on the Si(001) surface were determined by comparison between the experimental STM images and the theoretical simulations. Maximizing the number of the Si-O bonds is more crucial than that of the Si-C bonds in the PTCDA adsorption.
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January 2025
State Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China.
The behavior of vicinal Si(001) surfaces are a subject of intense research for years, yet the mechanism behind its step modulation remains unresolved. Step B, in particular, can meander randomly or form a periodic zigzag profile, a surface phenomenon that has eluded explanation due to the lack of appropriate simulation tools. Here, a multiscale simulation strategy, enhanced by machine learning potentials are proposed, to investigate this mesoscale behavior.
View Article and Find Full Text PDFNanotechnology
October 2024
IHP-Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany.
We investigate the nanoheteroepitaxy (NHE) of SiGe and Ge quantum dots (QDs) grown on nanotips (NTs) substrates realized in Si(001) wafers. Due to the lattice strain compliance, enabled by the nanometric size of the tip and the limited dot/substrate interface area, which helps to reduce dot/substrate interdiffusion, the strain and SiGe composition in the QDs could be decoupled. This demonstrates a key advantage of the NHE over the Stranski-Krastanow growth mechanism.
View Article and Find Full Text PDFJ Phys Chem Lett
July 2024
Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany.
Selective adsorption of multifunctional molecules is rarely observed when the different functional groups react via nonactivated reaction channels. Although the latter is also the case for ether cleavage and the adsorption of C=C double bonds on the highly reactive Si(001) surface, we find that allyl ethers, which combine both functional groups, react on Si(001) selectively via the cleavage of the molecules' ether group. In addition, our XPS measurements at 90, 150, and 300 K indicate an increased reactivity of the ether group when compared to monofunctional ethers.
View Article and Find Full Text PDFNat Commun
January 2024
London Centre for Nanotechnology, University College London, WC1H 0AH, London, UK.
Atomically precise hydrogen desorption lithography using scanning tunnelling microscopy (STM) has enabled the development of single-atom, quantum-electronic devices on a laboratory scale. Scaling up this technology to mass-produce these devices requires bridging the gap between the precision of STM and the processes used in next-generation semiconductor manufacturing. Here, we demonstrate the ability to remove hydrogen from a monohydride Si(001):H surface using extreme ultraviolet (EUV) light.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2024
School of Energy and Environment Science, Yunnan Normal University, Kunming, Yunnan Province 650500, People's Republic of China.
III-V/Si multi-junction solar cells have been widely studied in recent years due to their excellent theoretical efficiency (∼42%). In order to solve the problem of lattice mismatch between Si and III-V compounds of III-V/Si solar cells, different hexagonal SiGe buffer layer models on the surface of hexagonal diamond Si(001) were built, and the structural, electronic and optical properties of the proposed models were calculated based on first principles calculations. The results showed that all models of the designed buffer layer could effectively reduce the lattice mismatch, and the buffer layer hex-SiGe ( = 0, 0.
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