Theory of Doping of Diamond

1992 ◽  
Vol 242 ◽  
Author(s):  
J. Bernholc ◽  
S. A. Kajihara ◽  
A. Antonelli
Keyword(s):  
Activation Energy ◽  
Large Scale ◽  
Natural Diamond ◽  
Tetrahedral Site ◽  
Shallow Donor ◽  
Native Defects ◽  
Self Diffusion ◽  
P Type ◽  
First Time ◽  
Very High

ABSTRACTElectronic applications of diamond require control over native defects as well as the ability to dope it p- and n-type. B is an excellent p-type dopant, but n-type doping has proven very difficult. Diamond films have also been very difficult to anneal, indicating a high activation energy for self-diffusion. We have investigated the properties of native defects and impurities through large-scale band structure and Car-Parrinello calculations. We indeed find that the activation energy for self-diffusion is very high in the intrinsic material, but it decreases by as much as 3 eV in either p- or n-type material. P, Li, and Na are shallow donors, but their solubilities are too low for incorporation into diamond through in-diffusion. It is energetically favorable for B and N to dissolve in diamond, which explains their prevalence in natural diamond. The calculations explain for the first time the reasons for the distortion of atoms around N from the fully tetrahedral site, as well as why N is a deep rather than a shallow donor. We also consider the effects of simultaneous doping with N and B on the thermodynamic equilibrium between diamond and graphite.

scholarly journals Shell-crossing in a ΛCDM Universe

2020 ◽  
Vol 501 (1) ◽  
pp. L71-L75
Author(s):  
Cornelius Rampf ◽  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Perturbation Theory ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Three Dimensional ◽  
Random Initial Data ◽  
Recursion Relations ◽  
Indispensable Tool ◽  
First Time ◽  
Very High

ABSTRACT Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of perturbation theory is shell-crossing, which is the instance when cold-dark-matter trajectories intersect for the first time. We investigate Lagrangian perturbation theory (LPT) at very high orders in the vicinity of the first shell-crossing for random initial data in a realistic three-dimensional Universe. For this, we have numerically implemented the all-order recursion relations for the matter trajectories, from which the convergence of the LPT series at shell-crossing is established. Convergence studies performed at large orders reveal the nature of the convergence-limiting singularities. These singularities are not the well-known density singularities at shell-crossing but occur at later times when LPT already ceased to provide physically meaningful results.

Recent Developments in Doping Techniques for Compound Semiconductors

1993 ◽  
Vol 325 ◽  
Author(s):  
J. E. Cunningham ◽  
W. T. Tsang
Keyword(s):  
Activation Energy ◽  
Hole Concentration ◽  
Compound Semiconductors ◽  
Solubility Limit ◽  
Band Offset ◽  
New Methods ◽  
In Doping ◽  
Recent Developments ◽  
P Type ◽  
First Time

AbstractWe report new methods to dope compound semiconductors. First, we demonstrate the concept of doping engineering whereby it becomes possible to tailor the activation energy of the dopant in a host semiconductor for the first time. In this application, the band offset of a thin, sacrificial semiconductor is used to lower the activation energy of the dopant below its value in the host semiconductor. This allows the freedom to control dopant activity in ways not accessible to a uniformly placed dopant. We chose δ-Be-AlGaAs/GaAs as a model example and show the hole binding energy is reduced by a factor of five. Secondly, we demonstrate overcoming the p-type solubility limit in GaAs by use of monolayer δ-Be in a GaAs base of an HBT. Here, an effective hole concentration of > 1021cm−3 is measured in real devices. We present a qualatative view of doping solubility limitations that are controlled by surface processes.

Native Defects in Diamond, Sic, and Si: Energetics and Self-Diffusion

1988 ◽  
Vol 141 ◽  
Author(s):  
A. Antonelli ◽  
C. Wang ◽  
J. Bemholc ◽  
R. F. Davis
Keyword(s):  
Group Iv ◽  
Type Material ◽  
Native Defects ◽  
Self Diffusion ◽  
Direct Exchange ◽  
Group Iv Semiconductors ◽  
Relative Contribution ◽  
Diffusion Phenomena ◽  
Rich Material ◽  
P Type

AbstractWe have investigated, via first principles total energy calculations, the energetics of elementary native defects in group IV semiconductors. Its implications on the relative abundance of these defects and self-diffusion phenomena are analyzed. The results show that in diamond the self-diffusion is dominated by vacancies, because the interstitial and direct exchange mechanisms have much greater activation energy. In SiC stoichiometry plays an important role. For Si-rich compound, Sic-antisite is the dominant defect in the intrinsic and p-type material, while the carbon vacancy is dominant in the n-type material. For C-rich material, the Csi-antisite is dominant regardless the position of the Fermi level. In Si, it well-known that the vacancy, interstitial and direct exchange mechanisms have very similar activation energies. Our results suggest that self-diffusion experiments carried out at various pressures can determine the relative contribution of each of these mechanisms.

Triple-Junction Thin-Film Silicon Solar Cells on W-Textured ZnO for Applications to Low-Concentration Photovoltaics

2013 ◽  
Vol 1493 ◽  
pp. 219-224
Author(s):  
Shunsuke Kasashima ◽  
Yuki Moriya ◽  
Porponth Sichanugrist ◽  
Makoto Konagai
Keyword(s):  
Solar Cells ◽  
Triple Junction ◽  
Silicon Solar Cells ◽  
Low Concentration ◽  
Intermediate Layers ◽  
P Type ◽  
First Time ◽  
Very High ◽  
A Current ◽  
Light Scattering Effect

ABSTRACTWe report for the first time the a-Si:H/μc-Si:H/μc-Si:H triple-junction solar cells fabricated on W-textured ZnO having a very high haze value which can improve light scattering effect. For further enhancement of light confinement effects, p-type a-SiOx:H and μc-SiOx:H as wide-gap window-layers, n-type μc-SiOx:H as intermediate layers and a back reflector were employed in these solar cells too. From theoretical analysis, we have found an advantage of a-Si:H/μc-Si:H/μc-Si:H structure for an application to low-concentration photovoltaics. For the fabricated solar cells, a conversion efficiency of 8.86% at 1 sun and and 9.86% under 7.2 suns, and a total photocurrent from each subcell of 24.1 mA/cm2 were achieved although there was still a current mismatch among component subcells.

Correlation of Microstructural Properties With Thermoelectric Performance of Bi0.5Sb1.5Te3 Films Fabricated by Electroplating

2010 ◽  
Vol 1267 ◽  
Author(s):  
Elena Koukharenko ◽  
Xiaohong Li ◽  
Jekaterina Kuleshova ◽  
Marcel Fowler ◽  
Nicole Frety ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Microstructural Properties ◽  
Fine Grained ◽  
Electrodeposited Film ◽  
P Type ◽  
First Time ◽  
Very High

AbstractThis study shows for the first time, the correlation between the microstructural properties (chemical composition and its homogeneity) and the thermoelectric properties for p-type Bi0.5Sb1.5Te3 electroplated films (10-15 μm thickness). High microstructural quality of Bi0.5Sb1.5Te3 electroplated films (a close to stoichiometry chemical composition with its high homogeneity elements distribution) was achieved by using an additive in the plating solution (sodium ligninsulfonate) as a surfactant agent. A fine-grained microstructure of 280 nm to 1μm has been observed for these materials, which half that of the plated films without a surfactant. The thermoelectric properties of electrodeposited Bi0.5Sb1.5Te3 films obtained without microstructural optimisation, show modest Seebeck coefficient values of 20-120 μm/K, electrodeposited film with an optimised microstructure exhibits very high values of Seebeck coefficient of 220-300 μm/K.

Scheming

2018 ◽  
Author(s):  
Seán Damer
Keyword(s):  
Social Class ◽  
Housing Policy ◽  
Large Scale ◽  
Class Structure ◽  
Local Council ◽  
Housing Scheme ◽  
Post War ◽  
First Time ◽  
The Voice ◽  
House Building

This book seeks to explain how the Corporation of Glasgow, in its large-scale council house-building programme in the inter- and post-war years, came to reproduce a hierarchical Victorian class structure. The three tiers of housing scheme which it constructed – Ordinary, Intermediate, and Slum-Clearance – effectively signified First, Second and Third Class. This came about because the Corporation uncritically reproduced the offensive and patriarchal attitudes of the Victorian bourgeoisie towards the working-class. The book shows how this worked out on the ground in Glasgow, and describes the attitudes of both authoritarian housing officials, and council tenants. This is the first time the voice of Glasgow’s council tenants has been heard. The conclusion is that local council housing policy was driven by unapologetic considerations of social class.

Effect of Cu doping on the electrical Properties of ZnTe by Vacuum Thermal Evaporation

2018 ◽  
Vol 31 (3) ◽  
pp. 20
Author(s):  
Sarmad M. M. Ali ◽  
Alia A.A. Shehab ◽  
Samir A. Maki
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Hall Mobility ◽  
Cu Doping ◽  
Before And After ◽  
Hall Effect Measurements ◽  
Evaporation Technique ◽  
P Type

In this study, the ZnTe thin films were deposited on a glass substrate at a thickness of 400nm using vacuum evaporation technique (2×10-5mbar) at RT. Electrical conductivity and Hall effect measurements have been investigated as a function of variation of the doping ratios (3,5,7%) of the Cu element on the thin ZnTe films. The temperature range of (25-200°C) is to record the electrical conductivity values. The results of the films have two types of transport mechanisms of free carriers with two values of activation energy (Ea1, Ea2), expect 3% Cu. The activation energy (Ea1) increased from 29meV to 157meV before and after doping (Cu at 5%) respectively. The results of Hall effect measurements of ZnTe , ZnTe:Cu films show that all films were (p-type), the carrier concentration (1.1×1020 m-3) , Hall mobility (0.464m2/V.s) for pure ZnTe film, increases the carrier concentration (6.3×1021m-3) Hall mobility (2m2/V.s) for doping (Cu at 3%) film, but  decreases by increasing Cu concentration.

scholarly journals Assessing Annual Actual Evapotranspiration Based on Climate, Topography and Soil in Natural and Agricultural Ecosystems

Climate ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 20
Author(s):  
Kleoniki Demertzi ◽  
Vassilios Pisinaras ◽  
Emanuel Lekakis ◽  
Evangelos Tziritis ◽  
Konstantinos Babakos ◽  
...  
Keyword(s):  
Water Balance ◽  
Large Scale ◽  
Hydrological Model ◽  
Actual Evapotranspiration ◽  
Irrigated Agriculture ◽  
Climate Data ◽  
Natural Ecosystems ◽  
Loading Effects ◽  
Very High ◽  
Of Greece

Simple formulas for estimating annual actual evapotranspiration (AET) based on annual climate data are widely used in large scale applications. Such formulas do not have distinct compartments related to topography, soil and irrigation, and for this reason may be limited in basins with high slopes, where runoff is the dominant water balance component, and in basins where irrigated agriculture is dominant. Thus, a simplistic method for assessing AET in both natural ecosystems and agricultural systems considering the aforementioned elements is proposed in this study. The method solves AET through water balance based on a set of formulas that estimate runoff and percolation. These formulas are calibrated by the results of the deterministic hydrological model GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) for a reference surface. The proposed methodology is applied to the country of Greece and compared with the widely used climate-based methods of Oldekop, Coutagne and Turk. The results show that the proposed methodology agrees very well with the method of Turk for the lowland regions but presents significant differences in places where runoff is expected to be very high (sloppy areas and areas of high rainfall, especially during December–February), suggesting that the proposed method performs better due to its runoff compartment. The method can also be applied in a single application considering irrigation only for the irrigated lands to more accurately estimate AET in basins with a high percentage of irrigated agriculture.

3.17% efficient Cu2ZnSnS4–BiVO4 integrated tandem cell for standalone overall solar water splitting

2021 ◽  
Author(s):  
Dingwang Huang ◽  
Kang Wang ◽  
Lintao Li ◽  
Kuang Feng ◽  
Na An ◽  
...  
Keyword(s):  
Water Splitting ◽  
Large Scale ◽  
Tandem Cell ◽  
Solar Water ◽  
Solar Water Splitting ◽  
First Time

3.17% efficient Cu2ZnSnS4–BiVO4 integrated tandem cell and a large scale 5 × 5 cm integrated CZTS–BiVO4 tandem device for standalone overall solar water splitting was assembled for the first time.

scholarly journals Development of Efficient and Selective Processes for the Synthesis of Commercially Important Chlorinated Phenols

Organics ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 142-160
Author(s):  
Keith Smith ◽  
Gamal A. El-Hiti
Keyword(s):  
Lewis Acid ◽  
Large Scale ◽  
Commercial Application ◽  
Chlorinated Phenols ◽  
Sulphur Compounds ◽  
Inorganic Solids ◽  
Solvent Free Conditions ◽  
Commercially Important ◽  
Ortho Cresol ◽  
Very High

para-Selective processes for the chlorination of phenols using sulphuryl chloride in the presence of various sulphur-containing catalysts have been successfully developed. Several chlorinated phenols, especially those derived by para-chlorination of phenol, ortho-cresol, meta-cresol, and meta-xylenol, are of significant commercial importance, but chlorination reactions of such phenols are not always as regioselective as would be desirable. We, therefore, undertook the challenge of developing suitable catalysts that might promote greater regioselectivity under conditions that might still be applicable for the commercial manufacture of products on a large scale. In this review, we chart our progress in this endeavour from early studies involving inorganic solids as potential catalysts, through the use of simple dialkyl sulphides, which were effective but unsuitable for commercial application, and through a variety of other types of sulphur compounds, to the eventual identification of particular poly(alkylene sulphide)s as very useful catalysts. When used in conjunction with a Lewis acid such as aluminium or ferric chloride as an activator, and with sulphuryl chloride as the reagent, quantitative yields of chlorophenols can be obtained with very high regioselectivity in the presence of tiny amounts of the polymeric sulphides, usually in solvent-free conditions (unless the phenol starting material is solid at temperatures even above about 50 °C). Notably, poly(alkylene sulphide)s containing longer spacer groups are particularly para-selective in the chlorination of m-cresol and m-xylenol, while, ones with shorter spacers are particularly para-selective in the chlorination of phenol, 2-chlorophenol, and o-cresol. Such chlorination processes result in some of the highest para/ortho ratios reported for the chlorination of phenols.

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