The adsorption of isolated H atoms on the Ge(001) surface is studied using density functional theory (DFT) and scanning tunneling microscopy (STM). Two stable adsorption positions that are found in DFT correspond to H atom attachment to an up-or down-buckled Ge dimer atom, respectively. Surprisingly, in the case where H bonds to the down-buckled Ge atom, we find that there is a redistribution of a unit of charge which leaves the net charge of the doubly occupied dangling bond of the unreacted Ge atom intact. This configuration is found to be the more stable of the two structures. Comparison to filled- and empty-state STM images confirms that this lowest energy structure is observed at room temperature. These results represent a fundamentally different picture of the physics and chemistry of H adsorption to Ge(001) compared with previous work.
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http://dx.doi.org/10.1063/1.3456736 | DOI Listing |
It is a long-standing goal to fabricate conductive molecular nanowires (NWs) on semiconductor surfaces. Anchoring molecules to pre-patterned surface nanostructures is a practical approach to construct molecular NWs on semiconductor surfaces. Previously, well-ordered inorganic Ge NWs were deduced to spontaneously grow onto Pt/Ge(001) surfaces after annealing at an elevated temperature.
View Article and Find Full Text PDFMolecules
June 2022
Łukasiewicz Research Network, Institute of Microelectronics and Photonics, Al. Lotnikow 32/46 Str., 02-668 Warsaw, Poland.
The problem of graphene protection of Ge surfaces against oxidation is investigated. Raman, X-Ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements of graphene epitaxially grown on Ge(001)/Si(001) substrates are presented. It is shown that the penetration of water vapor through graphene defects on Gr/Ge(001)/Si(001) samples leads to the oxidation of germanium, forming GeO.
View Article and Find Full Text PDFNanomaterials (Basel)
April 2022
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
Beyond the macroscopic perspective, this study microscopically investigates SiGe(001)-2×1 samples that were grown on the Ge(001) and Si(001) substrates via molecular-beam epitaxy, using the high-resolution synchrotron radiation photoelectron spectroscopy (SRPES) as a probe. The low-energy electron diffraction equipped in the SRPES chamber showed 2×1 double-domain reconstruction. Analyses of the Ge 3d core-level spectra acquired using different photon energies and emission angles consistently reveal the ordered spots to be in a Ge-Ge tilted configuration, which is similar to that in Ge(001)-2×1.
View Article and Find Full Text PDFJ Phys Chem Lett
February 2022
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
The manipulation of conductive nanowires (NWs) on semiconductor platforms provides important insights into the fabrication of nanoscale electronic devices. In this work, we directly observed the electric field-induced phase transitions in atomic Au-NWs self-assembled on Ge(001) surfaces using scanning tunneling microscopy (STM). The tunneling electrons and electric fields underneath a STM tip apex can effectively trigger a phase transition in Au-NWs on Ge(001) surfaces.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2020
IHP-Leibniz-Institut für Innovative Mikroelektronik , Im Technologiepark 25 , 15236 Frankfurt (Oder) , Germany.
The oxidation behavior of Ge(001) and Ge(110) surfaces underneath the chemical vapor deposition (CVD)-grown graphene films has been investigated experimentally and interpreted on the basis of ab initio calculations. Freshly grown samples were exposed to air for more than 7 months and periodically monitored by X-ray photoelectron spectroscopy, scanning electron microscopy, and Raman spectroscopy. The oxidation of Ge(110) started with incubation time of several days, during which the oxidation rate was supposedly exponential.
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