scholarly journals Investigation on the impact of hydrogen on the passivation of silicon surface states in clean and copper contaminated conditions

AIP Advances ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 105102 ◽  
Author(s):  
Lihui Song ◽  
Deren Yang ◽  
Xuegong Yu
Keyword(s):  
Silicon Surface ◽  
Surface States ◽  
Copper Contaminated ◽  
The Impact

scholarly journals Many-impurity scattering on the surface of a topological insulator

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Luis Hernando ◽  
Yuriko Baba ◽  
Elena Díaz ◽  
Francisco Domínguez-Adame
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Topological Insulator ◽  
Disordered Systems ◽  
Spectral Properties ◽  
Random Distribution ◽  
Surface States ◽  
Impurity Scattering ◽  
Self Consistent ◽  
The Impact

AbstractWe theoretically address the impact of a random distribution of non-magnetic impurities on the electron states formed at the surface of a topological insulator. The interaction of electrons with the impurities is accounted for by a separable pseudo-potential method that allows us to obtain closed expressions for the density of states. Spectral properties of surface states are assessed by means of the Green’s function averaged over disorder realisations. For comparison purposes, the configurationally averaged Green’s function is calculated by means of two different self-consistent methods, namely the self-consistent Born approximation (SCBA) and the coherent potential approximation (CPA). The latter is often regarded as the best single-site theory for the study of the spectral properties of disordered systems. However, although a large number of works employ the SCBA for the analysis of many-impurity scattering on the surface of a topological insulator, CPA studies of the same problem are scarce in the literature. In this work, we find that the SCBA overestimates the impact of the random distribution of impurities on the spectral properties of surface states compared to the CPA predictions. The difference is more pronounced when increasing the magnitude of the disorder.

scholarly journals Magnetic and defect probes of the SmB6 surface state

2018 ◽  
Vol 4 (11) ◽  
pp. eaau4886 ◽  
Author(s):  
Lin Jiao ◽  
Sahana Rößler ◽  
Deepa Kasinathan ◽  
Priscila F. S. Rosa ◽  
Chunyu Guo ◽  
...  
Keyword(s):  
Surface States ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Magnetic Impurities ◽  
Fundamental Physics ◽  
Length Scales ◽  
Kondo Insulator ◽  
Theoretical Predictions ◽  
The Impact

The impact of nonmagnetic and magnetic impurities on topological insulators is a central focus concerning their fundamental physics and possible spintronics and quantum computing applications. Combining scanning tunneling spectroscopy with transport measurements, we investigate, both locally and globally, the effect of nonmagnetic and magnetic substituents in SmB6, a predicted topological Kondo insulator. Around the so-introduced substitutents and in accord with theoretical predictions, the surface states are locally suppressed with different length scales depending on the substituent’s magnetic properties. For sufficiently high substituent concentrations, these states are globally destroyed. Similarly, using a magnetic tip in tunneling spectroscopy also resulted in largely suppressed surface states. Hence, a destruction of the surface states is always observed close to atoms with substantial magnetic moment. This points to the topological nature of the surface states in SmB6 and illustrates how magnetic impurities destroy the surface states from microscopic to macroscopic length scales.

Silicon Surface Preparation and Passivation by Vapor Phase of Heavy Water

2009 ◽  
Vol 145-146 ◽  
pp. 181-184 ◽  
Author(s):  
Andrea E. Pap ◽  
Zsolt Nényei ◽  
Gábor Battistig ◽  
István Bársony
Keyword(s):  
Silicon Surface ◽  
Surface States ◽  
Surface Preparation ◽  
Hydrogen Desorption ◽  
Dangling Bonds ◽  
Hydrogen Atoms ◽  
Surface Band ◽  
Band Bending ◽  
Chemical Treatments ◽  
Wet Chemical

The well known wet chemical treatments of the silicon surface and its native oxidation in air cause a high density of interface states, which predominantly originate from dangling bonds strained bonds or from bonds, between adsorbates and silicon surface atoms. Therefore, a number of wet-chemical treatments have been developed for ultraclean processing in order to produce chemically and electronically passivated surfaces [1]. The saturation of dangling bonds by hydrogen removes the surface states and replaces them by adsorbate-induced states, which influence the surface band-bending [2]. The first thermal hydrogen desorption peak from a hydrogen passivated Si surface in vacuum or inert gas ambient can be detected at around 380°C [3,4]. Simultaneously the combination of the hydrogen atoms of neighboring dihydrides generates a pair of dangling bonds. At around 480-500°C dangling bonds are generated on the silicon surface by desorption of the remaining hydrogen [5]. At that moment the silicon surface becomes extremely reactive.

Angular distribution of photoelectrons from (111) silicon surface states

1975 ◽  
Vol 12 (1) ◽  
pp. 298-300 ◽  
Author(s):  
M. M. Traum ◽  
J. E. Rowe ◽  
N. V. Smith
Keyword(s):  
Angular Distribution ◽  
Silicon Surface ◽  
Surface States

Characterization of GaS-Passivated Quantum-Well Laser Diodes

1999 ◽  
Vol 573 ◽  
Author(s):  
L. G. Vaughn ◽  
T. C. Newell ◽  
L. F. Lester ◽  
A. N. Macinnes
Keyword(s):  
Quantum Well ◽  
Radiative Recombination ◽  
Laser Diodes ◽  
Surface States ◽  
Ridge Waveguide ◽  
Pulsed Power ◽  
Quantum Well Laser ◽  
Heating Effects ◽  
The Impact

ABSTRACTThe degradation of AlGaAs/GaAs diode laser performance during operation is typically due to catastrophic optical damage of the facets caused when thermal runaway occurs. These heating effects are due to the presence of non-radiative recombination sites at and near the facets. MOCVD GaS is deposited on the facets of 825-nm ridge waveguide AlGaAs/GaAs quantumwell laser diodes as an electronic passivation to reduce the number of surface states available for non-radiative recombination. For passivated devices, a peak pulsed power nearly double that of unpassivated devices was achieved. The passivated devices also exhibit a longer lifetime before degradation. The impact of the passivation process on other optical characteristics of the laser diodes will also be discussed.

Effects of TCO/a-Si:C:H Interface Defect States on p-i-n a-Si:H Solar Cell Performance

1994 ◽  
Vol 336 ◽  
Author(s):  
Franc Smole ◽  
Marko Topič
Keyword(s):  
Solar Cell ◽  
Surface States ◽  
Potential Drop ◽  
Defect States ◽  
Solar Cell Performance ◽  
Photoelectric Properties ◽  
Interface Defect ◽  
Work Function Difference ◽  
The Impact ◽  
Defect Densities

ABSTRACTTo explain realistic circumstances with regard to energy band profiles at the TCO/a-Si:C:H heterojunction, the ASPIN computer simulation has been used. Numerical calculations indicate that the increased interface defect densities result in a steep potential drop inside the interface region, while the rest of the work function difference extends into the p-layer. The detrimental effect of a-Si:C:H partial oxidation has been simulated by additionally increased density of states at a-Si:C:H surface, and its influence on the potential barrier has been analyzed. The impact of both TCO/a-Si:C:H interface states and a-Si:C:H surface states on the photoelectric properties of p-i-n a-Si:H solar cell is discussed, and a possible improvement of Voc is envisaged.

scholarly journals Scanning tunneling spectroscopic monitoring of surface states role on water passivation of InGaAs uncapped quantum dots

RSC Advances ◽  
2017 ◽  
Vol 7 (53) ◽  
pp. 33137-33142
Author(s):  
M. J. Milla ◽  
I. Hernández-Rodríguez ◽  
J. Méndez ◽  
Jorge M. García ◽  
J. M. Ulloa ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Surface States ◽  
Surface Conductivity ◽  
Local Analysis ◽  
Scanning Tunneling ◽  
Nanometer Scale ◽  
Spectroscopic Monitoring ◽  
Surface Nanostructures ◽  
The Impact

A detailed local analysis of the impact of water coverage on the density of surface states in In0.5Ga0.5As surface nanostructures is reported by spectroscopy monitoring the surface conductivity at the nanometer-scale.

Ab Initio Study of Clean and Hydrogen-Saturated Unreconstructed SiC{0001} Surfaces

2007 ◽  
Vol 556-557 ◽  
pp. 493-496 ◽  
Author(s):  
Alexander Mattausch ◽  
T. Dannecker ◽  
Oleg Pankratov
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Surface States ◽  
Correlation Effects ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Hubbard U ◽  
The Impact ◽  
Good Agreement

Using density functional theory, we investigate the 6H-SiC{0001} surfaces in the unreconstructed 1 × 1 and the H-passivated configuration. The strong correlation effects of the dangling bonds at the surface are treated by spin-polarised calculations including the Hubbard-U parameter. We find that the clean surfaces are semiconducting with surface states in good agreement with experimental data. The impact of the Hubbard-U is stronger on the C-terminated face. For the H-passivated surfaces we find resonances in the valence band. The antibonding C−H state is located in the upper part of the bandgap around the ¯􀀀-point.

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