Ge(001) surface reconstruction studied using a first-principles calculation and a Monte Carlo simulation

Yoshimoto, Yoshihide; Nakamura, Yoshimichi; Kawai, Hiroshi; Tsukada, Masaru; Nakayama, Minoru

doi:10.1103/physrevb.61.1965

Cited by 62 publications

(50 citation statements)

References 21 publications

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“…Moreover, the lattice is further stabilized by a distinct buckling pattern of the surface dimers, which leads to a c͑4 ϫ 2͒ superstructure at low temperatures. DFT-based structure optimization has fully reproduced x-ray diffraction data for the clean Ge͑001͒ surface 30,31 and, in addition, showed a good agreement for the resulting surface electronic states. 32 We simulate the Ge͑001͒ surface by means of repeated asymmetric slabs of eight Ge layers and a vacuum region of the same size.…”

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confidence: 75%

First-principles description of atomic gold chains on Ge(001)

et al. 2010

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We have performed density-functional theory calculations, including the spin-orbit correction, to investigate atomic gold chains on Ge͑001͒. A set of 26 possible configurations of the Au/Ge͑001͒ system with c͑4 ϫ 2͒ and c͑8 ϫ 2͒ symmetries is studied. Our data show that the c͑4 ϫ 2͒ order results in the lowest energy, which is not in direct agreement with recent experiments. Using total-energy calculations, we are able to explain these differences. We address the electronic band structure and apply the Tersoff-Hamann approach to correlate our data to scanning-tunneling microscopy ͑STM͒. We obtain two highly competitive structures of the atomic Au chains for which we report simulated STM images in order to clarify the composition of the experimental Au/Ge͑001͒ surface. is limited to a chain length of several ten atoms, utilization of self-organization processes of adatoms on surfaces can lead to much longer chains. These chains are of great interest both for basic research and for various applications because they give rise to a ͑quasi-͒ one-dimensional electron system. In this context, Schäfer et al. 5 recently discovered a new system: self-organized atomic Au chains on Ge͑001͒ with a c͑8 ϫ 2͒ long-range order. These Au nanowires appear to be largely decoupled from the Ge substrate and therefore have been put forward as a model system for a Luttinger liquid. [6][7][8] Self-organized In wires on Si͑111͒ ͑Ref. 9͒ and Au wires on Si͑533͒, 10 on the contrary, have been found to exhibit a significant coupling to the substrate. For the Ge͑001͒ surface, Au growth, in general, comes along with a large variety of ordering phenomena as a function of both coverage and growth temperature.11 The Ge͑001͒ surface thereby is subject to a strong relaxation. In particular, a missing-row reconstruction with emerging microfacets of the Ge͑111͒ type, 12 which is known from the clean Au͑110͒, Ir͑110͒, and Pt͑110͒ surfaces, 13,14 has been reported. Adsorption of Pt atoms on Ge͑001͒ results in highly ordered arrays of nanowires, which show very little defects and reach lengths of several 100 nm. 15,16 The latter system has been investigated in detail 17,18 by ab initio calculations based on the density-functional theory ͑DFT͒, 19 demonstrating the capacity of ab initio methods for interpreting experimental data, particularly, from STM and angular-resolved photoelectron spectroscopy. Specifically, the pseudopotential method provides useful information by accurate theoretical STM images, which help to understand experimental data. 20Our findings are based on total-energy DFT calculations in the framework of the projector-augmented wave method, 21,22 using the Vienna ab initio simulation package. 23,24 For the exchange-correlation functional, we apply the generalized gradient approximation and the PerdewBurke-Ernzerhof scheme. 25 All our data have been obtained under the inclusion of the spin-orbit coupling, which is essential for describing the electronic as well as optical properties of Au systems. 26 We use a 250-eV-plane-wave energy c...

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confidence: 75%

First-principles description of atomic gold chains on Ge(001)

et al. 2010

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“…In case of the pinned-buckled dimers of the c4 2 domain, the D up bonds are relatively more populated with respect to the D down bonds. In the case of the symmetric-appearing dimers in the 2 1 domains, the D down and D up bonds are almost equally populated-in a time averaged manner-due to the high frequency of the flip-flopping of the dimers between two buckled states [10,17]. Consequently, a band that would form due to D up bonds can be expected to appear sharper in c4 2 domains, while the same band in 2 1 would look more smeared or attached to a nearby, high-intensity, state as a shoulder.…”

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confidence: 99%

“…First, it is well established that the 2 1 domains are composed of nonfrozen/flip-flopping dimers [10,11,17]. Theoretically, the dimers are shown to be frozen as buckled due to an energy gain [19,20].…”

Section: Fig 2 (A)mentioning

confidence: 99%

Electronic Properties of(2×1)andc(4×2)Domains on Ge(001) Studied by Scanning Tunneling

2004

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The surface electronic structure of Ge(001) was studied by scanning tunneling spectroscopy. The measured surface densities of states unequivocally reveal the presence of a metallic state on the 2 1 domains, which is absent on the c4 2 domains. This metallic state, so far observed only in integral measurements, is attributed to the flip-flopping dimers that constitute the 2 1 domains. Our data also reveal a set of previously unresolved surface states, in perfect agreement with published theoretical predictions.

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“…At low temperatures the reconstruction is of periodicity c(2 · 4), which transforms into a structure of periodicity (2 · 1) when the temperature is increased [5][6][7]. Recent ab initio calculations [8] have been performed to investigate the adsorption of GeH 2 on Si(0 0 1)-(2 · 1).…”

Section: Introductionmentioning

confidence: 99%