Electronic structure of the thallium-induced<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math>reconstruction on Si(001)

Eriksson, Peter; Sakamoto, Kazuyuki; Uhrberg, R. I. G.

doi:10.1103/physrevb.81.205422

Cited by 11 publications

(13 citation statements)

References 20 publications

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“…The chemical shift (De ¼ À0.5 eV) observed for the interfacial Ge component appears similar to Ge (001) surface dimerization. 57 A similar chemical shift (À0.46 eV) is expected for Ge-Hf bonding from first-principles calculations. 58 The percentage of the Ge 3d 5/2 component associated with the lower binding energy relative to the entire Ge signal is shown to increase with temperature.…”

Section: Crystallization Temperature and The Srhfo 3 -Ge Interfacesupporting

confidence: 50%

Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications

McDaniel

et al. 2015

Journal of Applied Physics

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The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO3 (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10−5 A/cm2 at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (Dit) is estimated to be as low as ∼2 × 1012 cm−2 eV−1 under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased Dit value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications.

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Section: Crystallization Temperature and The Srhfo 3 -Ge Interfacesupporting

confidence: 50%

Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications

McDaniel

et al. 2015

Journal of Applied Physics

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“…This surface is known to reconstruct through the formation of rows of buckled dimers and has been characterized in detail by high resolution XPS. [50][51][52][53] Given the fact that the surface core-level shifts are at most 0.5 eV, the calculations in this section are only performed at the PBE level. Indeed, for such small shifts the estimated improvement achieved through the use of a hybrid functional would not exceed the overall expected accuracy.…”

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confidence: 99%

Germanium core-level shifts at Ge/GeO2interfaces through hybrid functionals

et al. 2012

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The Ge core-level shift across the Ge/GeO2 interface is determined within semilocal and hybrid density functional schemes. We first assess the accuracy achieved within these theoretical frameworks by comparing calculated and measured core-level shifts for a set of Ge-based molecules. The comparison with experimental data results in rms deviations of 0.19 and 0.09 eV for core-level shifts calculated with semilocal and hybrid density functionals, respectively. We also compare calculated core-level shifts at the Ge(001)-c(4 × 2) surface with high-resolution X-ray photoemission spectra finding similar agreement. We then turn to the Ge/GeO2 interface, which we describe with atomistic superlattice models showing alternating layers of Ge and GeO2. The adopted models include a substoichiometric transition region in which all Ge atoms are fourfold coordinated and all O atoms are twofold coordinated, as inferred for Si/SiO2 interfaces. Since the calculation of core-level shifts involves charged systems subject to finite-size effects, we use two different methods to ascertain the core-level shift ∆EXPS between the oxidation state Ge 0 and Ge +4 across the interface. In the first method, core-hole relaxations are first evaluated in bulk models of the interface components and then complemented by the initial-state shift calculated across the interface, while the second method consists in direct interface calculations corrected through classical electrostatics. Using the more accurate hybrid functional scheme, we obtain a shift ∆EXPS of 2.7 ± 0.1 eV. This value is significantly lower than experimental data, which typically fall around 3.3 eV or higher, but the underestimation is consistent with that found for the valence band offset of the same model. This leads to the conclusion that the adopted model structures yield an incorrect description of the interface dipole and emphasizes that Ge/GeO2 interfaces possess different structural properties than their silicon counterparts.

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“…4(a) and (b), respectively. Because of the ultra-high vacuum and the preparation process, standard Si(001)-(2x1) reconstruction [16] was presented with rows of dimers. The surface of the Si is not perfect with rows of defects.…”

Section: Resultsmentioning

confidence: 99%

Electronic Structure and Infrared Light Emission in Dislocation-Engineered Silicon

Hsin

Teng

Lin

et al. 2015

IEEE Trans. Nanotechnology

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One of the perspectives of the Si-based technology is the optical interconnect for data transmission and applications in optoelectronic integrated circuit. In this report, the engineered dislocation network was proposed and the atomic structure of the dislocation array was revealed by high-resolution transmission electron microscope (HRTEM) and scanning tunneling microscope (STM). The photoluminescence (PL) emission is strong and compatible with intrinsic Si characteristic peak, making it possible as light emitters in silicon. The analysis of dislocation array-induced scanning tunneling spectroscopy (STS) identified the presence of defect levels under the conduction band, compared with the occupied and unoccupied Kohn-Sham orbitals in the forbidden gap of Si derived from first-principles theoretical models. This study demonstrated the possibility of dislocation-induced optical transition from a theoretical and experimental perspective, which will be essential in the development of Si-based optoelectronic integrated circuit.

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Electronic structure of the thallium-induced2×1reconstruction on Si(001)

Cited by 11 publications

References 20 publications

Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications

Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications

Germanium core-level shifts at Ge/GeO2interfaces through hybrid functionals

Electronic Structure and Infrared Light Emission in Dislocation-Engineered Silicon

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