Surface and bulk properties of GaAs(001) treated by selenium layers

Feng, Peter; Riley, J.D.; Leckey, Robert; Pigram, Paul J.; Hollering, M.; Ley, L.

doi:10.1016/s0039-6028(00)00797-4

Cited by 7 publications

(14 citation statements)

References 15 publications

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“…al also obtained an Se3d signal spanning from ∼51 to 60 eV, with two independent contributions, and the peak separation between reduced Se and elemental Se was about 3 eV . A literature survey on Se 3d shows that the core-level spectrum tends to extend over a rather broad binding energy range of 50−62 eV, – indicating that Se can produce signals within this range, depending on its oxidation state and chemical environment.…”

Section: Resultsmentioning

confidence: 99%

Charge Transport and Electrochromism in Novel Nanocomposite Films of Poly(3,4-ethylenedioxythiophene)-Au Nanoparticles−CdSe Quantum Dots

et al. 2010

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Nanocomposite films of Poly(3,4-ethylenedioxythiophene)-Au-CdSe have been fabricated for the first time by first growing a porous PEDOT layer in the ionic liquid l-butyl-I-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and then introducing the film to a mixed colloid of Au nanoparticles (NPs) and CdSe quantum dots (QDs), thereby imparting a uniform confinement of Au NPs/CdSe QDs nanocomposite to the bulk of the polymer film by the virtue of affinity that Au has for the sulfur on the thiophene rings. Progressive luminescence quenching and absorption enhancement of CdSe QDs as a function of Au NPs incorporation in the CdSe colloid confirmed the direction of charge transfer from CdSe QDs to Au NPs. The optimized composition of Au-CdSe based on a maximum charge transfer was utilized for the formation of the nanocomposite with PEDOT. The loss of electrons from CdSe in the nanocomposite was also reflected in the core level signals of Se 3d corresponding to oxidized states of Se 2 + and SeQ. The charge propagation from CdSe to Au to PEDOT through Fermi-level equilibration was also confirmed by luminescence and absorption spectroscopy. The effect of Au-CdSe on electrochromic performance of the nanocomposite film was realized in terms of a superior optical density change, larger coloring efficiency (300 cm 2 C-1 , A = 550 nm), and faster colorbleach kinetics when compared with the electroactivity of the control PEDOT film, grown without the inclusion of any nanomoiety.

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Section: Resultsmentioning

confidence: 99%

Charge Transport and Electrochromism in Novel Nanocomposite Films of Poly(3,4-ethylenedioxythiophene)-Au Nanoparticles−CdSe Quantum Dots

et al. 2010

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“…A 1.5 µm thickness GaAs(111)B epilayer was grown by MBE at Cardiff University, and protected with a micrometre thick As cap during transfer to BESSY1. A clean substrate GaAs surface was prepared in the growth chamber by gradually heating to around 450 • C, as described elsewhere [10,11]. After a sharp 2 × 2 LEED pattern appeared, the sample was transferred to the analyser chamber where angle-resolved photoemission spectra of Ga 3d, As 3d and valence bands were acquired to characterize the observed surface reconstruction.…”

Section: Experimental Conditionsmentioning

confidence: 99%

“…A lineshape analysis procedure for the core level spectra was employed to probe the composition of the clean surface and the reactions occurring at evolving interfaces. The basic method of analysis is the deconvolution of each core level lineshape into components representative of the surface, the bulk and the interface using a standard least-squares fitting routine as described elsewhere [10,11]. The lineshape deconvolution for all core levels was performed in a consistent way, in which we used a minimum number of components and fixed the spin-orbit splitting and the Lorentzian widths in the fit.…”

Section: Characterization Of Growthmentioning

confidence: 99%

“…The lineshape deconvolution for all core levels was performed in a consistent way, in which we used a minimum number of components and fixed the spin-orbit splitting and the Lorentzian widths in the fit. The starting values for the spin-orbit splitting, the branching ratio and the Lorentzian and Gaussian widths were obtained from clean surface data in the literature [6,7,[10][11][12][13]. The parameters acquired by fitting angle-integrated (from −90 • to +90 • ) spectra were those employed to decompose the angle-dependent emission of the same core level, for which only the intensities of each component were allowed to vary with angle in the fit.…”

Section: Characterization Of Growthmentioning

confidence: 99%

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Surface, interface and bulk properties of GaAs(111)B treated by Se layers

Feng

Riley

Leckey

et al. 2001

J. Phys. D: Appl. Phys.

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The surface and bulk properties of GaAs(111)B with Se surface layers of different thicknesses have been studied. Insight into the mechanism of this type of surface treatment has been provided by surface-sensitive photoemission spectroscopy. It has been found that Se deposited at room temperature on an As rich GaAs(111)B surface initially reacts with As followed by the formation of a Se overlayer. A relatively large spectral component due to Se-As bond emission was observed. The experimental results show that the Ga and As core levels shift around 0.27 eV after an initial Se deposition, and no additional shift was observed after further Se deposition.

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“…49,52 An arsenic-rich 2 × 4 surface is present before any treatment. However, for selenium exposure at room temperature, the surface arsenic atoms remain and only As−Se bonds are formed, 49,53 after which a selenium overlayer follows as deposition continues. It is reported that the surface structure changed from 2 × 4 to 2 × 1 while lowering the substrate temperature, before applying selenium flux.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Growth of the Van der Waals Materials Bi₂Se₃ and (Bi_0.5In_0.5)₂Se₃ by Molecular Beam Epitaxy

Wang

Law

2021

Crystal Growth & Design

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The naturally existing chalcogenide Bi 2 Se 3 is topologically nontrivial due to the band inversion caused by the strong spin-orbit coupling inside the bulk of the material. The surface states are spin polarized, protected by the time-inversion symmetry, and thus robust to the scattering caused by nonmagnetic defects. A high-purity topological insulator thin film can be easily grown via molecular beam epitaxy (MBE) on various substrates to enable novel electronics, optics, and spintronics applications. However, the unique surface state properties have historically been limited by the film quality, which is evaluated by crystallinity, surface morphology, and transport data. Here we propose and investigate different MBE growth strategies to improve the quality of Bi 2 Se 3 thin films grown by MBE. Based on the surface passivation status, we have classified the substrates into two categories, self-passivated or unpassivated, and determine the optimal growth mechanisms on the representative sapphire and GaAs, respectively. For Bi 2 Se 3 on GaAs, the surface passivation status determines the dominant growth mechanism. In the end, growths of the topological trivial insulator (Bi 0.5 In 0.5 ) 2 Se 3 (BIS) on GaAs are investigated following the protocols proposed.

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Surface and bulk properties of GaAs(001) treated by selenium layers

Cited by 7 publications

References 15 publications

Charge Transport and Electrochromism in Novel Nanocomposite Films of Poly(3,4-ethylenedioxythiophene)-Au Nanoparticles−CdSe Quantum Dots

Charge Transport and Electrochromism in Novel Nanocomposite Films of Poly(3,4-ethylenedioxythiophene)-Au Nanoparticles−CdSe Quantum Dots

Surface, interface and bulk properties of GaAs(111)B treated by Se layers

Optimization of the Growth of the Van der Waals Materials Bi₂Se₃ and (Bi_0.5In_0.5)₂Se₃ by Molecular Beam Epitaxy

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Surface and bulk properties of GaAs(001) treated by selenium layers

Cited by 7 publications

References 15 publications

Charge Transport and Electrochromism in Novel Nanocomposite Films of Poly(3,4-ethylenedioxythiophene)-Au Nanoparticles−CdSe Quantum Dots

Charge Transport and Electrochromism in Novel Nanocomposite Films of Poly(3,4-ethylenedioxythiophene)-Au Nanoparticles−CdSe Quantum Dots

Surface, interface and bulk properties of GaAs(111)B treated by Se layers

Optimization of the Growth of the Van der Waals Materials Bi2Se3 and (Bi0.5In0.5)2Se3 by Molecular Beam Epitaxy

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Optimization of the Growth of the Van der Waals Materials Bi₂Se₃ and (Bi_0.5In_0.5)₂Se₃ by Molecular Beam Epitaxy