13 research outputs found
Alkyne-Functionalized Cyclooctyne on Si(001): Reactivity Studies and Surface Bonding from an Energy Decomposition Analysis Perspective
The reactivity and bonding of an ethinyl-functionalized cyclooctyne on Si(001) is studied by means of density functional theory. This system is promising for the organic functionalization of semiconductors. Singly bonded adsorption structures are obtained by [2 + 2] cycloaddition reactions of the cyclooctyne or ethinyl group with the Si(001) surface. A thermodynamic preference for adsorption with the cyclooctyne group in the on-top position is found and traced back to minimal structural deformation of the adsorbate and surface with the help of energy decomposition analysis for extended systems (pEDA). Starting from singly bonded structures, a plethora of reaction paths describing conformer changes and consecutive reactions with the surface are discussed. Strongly exothermic and exergonic reactions to doubly bonded structures are presented, while small reaction barriers highlight the high reactivity of the studied organic molecule on the Si(001) surface. Dynamic aspects of the competitive bonding of the functional groups are addressed by ab initio molecular dynamics calculations. Several trajectories for the doubly bonded structures are obtained in agreement with calculations using the nudged elastic band approach. However, our findings disagree with the experimental observations of selective adsorption by the cyclooctyne moiety, which is critically discussed
Decoding Energy Decomposition Analysis: Machine-Learned Insights on the Impact of the Density Functional on the Bonding Analysis
The concept of chemical bonding is a crucial aspect of chemistry that aids in
understanding the complexity and reactivity of molecules and materials.
However, the interpretation of chemical bonds can be hindered by the choice of
the theoretical approach and the specific method utilized. This study aims to
investigate the effect of choosing different density functionals on the
interpretation of bonding achieved through energy decomposition analysis (EDA).
To achieve this goal, a data set was created, representing four bonding groups
and various combinations of functionals and dispersion correction schemes. The
calculations showed significant variation among the different functionals for
the EDA terms, with the dispersion correction terms exhibiting the highest
variability. More information was extracted by using unsupervised learning in
combination with dimensionality reduction on the data set. Results indicate
that, despite the differences in the EDA terms obtained from different
functionals, the functional has the least significant impact, suggesting
minimal influence on the bonding interpretation.Comment: 34 pages, 11 figure
Chemical bonding of HF, HCl, and H2O onto YF3 surfaces: quantification by first principles
The surfaces of waimirite ÎČ-YF3 have been studied for their fluorine and chlorine versus water affinity. Bonding patterns of HF, HCl, and H2O chemically adsorbed onto surfaces of (010), (100), (011), and (101) have been quantified by density functional theory applying energy decomposition analysis. We found that the adsorption of H2O is dominated by about 65% of electrostatics, which causes a low surface sensitivity and weak interactions. On the contrary, the adsorptions of HF and HCl are driven by strong hydrogen bonds resulting in a highly surface-dependent ratio of 30â60% electrostatic versus orbital contribution. Among the stoichiometric surfaces, the shortest and strongest hydrogen bonds and consequently most covalent bonding patterns are found within YF3 HCl. However, when including the preparation energy, each surface favors the adsorption of HF over HCl, which reproduces the higher affinity of yttrium towards fluoride over chloride, previously known for solutions, also for the solid state
Accurate first-principle bandgap predictions in strain-engineered ternary III-V semiconductors
Tuning the bandgap in ternary III-V semiconductors via modification of the
composition or the strain in the material is a major approach for the design of
optoelectronic materials. Experimental approaches screening a large range of
possible target structures are hampered by the tremendous effort to optimize
the material synthesis for every target structure. We present an approach based
on density functional theory efficiently capable of providing the bandgap as a
function of composition and strain. Using a specific density functional
designed for accurate bandgap computation (TB09) together with a band unfolding
procedure and special quasirandom structures, we develop a computational
protocol efficiently able to predict bandgaps. The approach's accuracy is
validated by comparison to selected experimental data. We thus map the phase
space of composition and strain (we call this the ``bandgap phase diagram'')
for several important III-V compound semiconductors: GaAsP, GaAsN, GaPSb,
GaAsSb, GaPBi, and GaAsBi. We show the application of these diagrams for
identifying the most promising materials for device design. Furthermore, our
computational protocol can easily be generalized to explore the vast chemical
space of III-V materials with all other possible combinations of III- and
V-elements.Comment: 13 pages, 7 figures, GitHub
(https://bmondal94.github.io/Bandgap-Phase-Diagram/
Synthesis of a rhodium(III) dinitrogen complex using a calix[4]arene-based diphosphine ligand
The synthesis and characterisation of the rhodium(III) dinitrogen complex [Rh(2,2â-biphenyl)(CxP2)(N2)]+ are described, where CxP2 is a trans-spanning calix[4]arene-based diphosphine and the dinitrogen ligand is projected into the cavity of the macrocycle
VisibleâLightâTriggered Photoswitching of Diphosphene Complexes
Although diphosphene transition metal complexes are known to undergo E to Z isomerization upon irradiation with UV light, their potential for photoswitching has remained poorly explored. In this study, we present diphosphene complexes capable of reversible photoisomerizations through haptotropic rearrangements. The compounds [(2-Îș2P,Îș6C)Mo(CO)2][OTf] (3âa[OTf]), [(2-Îș2P,Îș6C)Fe(CO)][OTf] (3âb[OTf]), and [(2-Îș2P)Fe(CO)4][OTf] (4[OTf]) were prepared using the triflate salt [(LC)P=P(Dipp)][OTf] (2[OTf) as a precursor (LC=4,5-dichloro-1,3-bis(2,6-diisiopropylphenyl)-imidazolin-2-yl; Dipp=2,6-diisiopropylphenyl, OTf=triflate). Upon exposure to blue or UV light (λ=400â
nm, 470â
nm), the initially red-colored η2-diphosphene complexes 3âa,b[OTf] readily undergo isomerization to form blue-colored η1-complexes [(2-Îș1P,Îș6C)M(CO)n][OTf] (5âa,b[OTf]; a: M=Mo, n=2; b: M=Fe, n=1). This haptotropic rearrangement is reversible, and the (Îș2P,Îș6C)-coordination mode gradually reverts back upon dissolution in coordinating solvents or more rapidly upon exposure to yellow or red irradiation (λ=590â
nm, 630â
nm). The electronic reasons for the reversible visible-light-induced photoswitching observed for 3âa,b[OTf] are elucidated by DFT calculations. These calculations indicate that the photochromic isomerization originates from the S1 excited state and proceeds through a conical intersection
Alkyne-Functionalized Cyclooctyne on Si(001): Reactivity Studies and Surface Bonding from an Energy Decomposition Analysis Perspective
The reactivity and bonding of an ethinyl-functionalized cyclooctyne on Si(001) is studied by means of density functional theory. This system is promising for the organic functionalization of semiconductors. Singly bonded adsorption structures are obtained by [2 + 2] cycloaddition reactions of the cyclooctyne or ethinyl group with the Si(001) surface. A thermodynamic preference for adsorption with the cyclooctyne group in the on-top position is found and traced back to minimal structural deformation of the adsorbate and surface with the help of energy decomposition analysis for extended systems (pEDA). Starting from singly bonded structures, a plethora of reaction paths describing conformer changes and consecutive reactions with the surface are discussed. Strongly exothermic and exergonic reactions to doubly bonded structures are presented, while small reaction barriers highlight the high reactivity of the studied organic molecule on the Si(001) surface. Dynamic aspects of the competitive bonding of the functional groups are addressed by ab initio molecular dynamics calculations. Several trajectories for the doubly bonded structures are obtained in agreement with calculations using the nudged elastic band approach. However, our findings disagree with the experimental observations of selective adsorption by the cyclooctyne moiety, which is critically discussed
Alkyne-Functionalized Cyclooctyne on Si(001): Reactivity Studies and Surface Bonding from an Energy Decomposition Analysis Perspective
The reactivity and bonding of an ethinyl-functionalized cyclooctyne on Si(001) is studied by means of density functional theory. This system is promising for the organic functionalization of semiconductors. Singly bonded adsorption structures are obtained by [2 + 2] cycloaddition reactions of the cyclooctyne or ethinyl group with the Si(001) surface. A thermodynamic preference for adsorption with the cyclooctyne group in the on-top position is found and traced back to minimal structural deformation of the adsorbate and surface with the help of energy decomposition analysis for extended systems (pEDA). Starting from singly bonded structures, a plethora of reaction paths describing conformer changes and consecutive reactions with the surface are discussed. Strongly exothermic and exergonic reactions to doubly bonded structures are presented, while small reaction barriers highlight the high reactivity of the studied organic molecule on the Si(001) surface. Dynamic aspects of the competitive bonding of the functional groups are addressed by ab initio molecular dynamics calculations. Several trajectories for the doubly bonded structures are obtained in agreement with calculations using the nudged elastic band approach. However, our findings disagree with the experimental observations of selective adsorption by the cyclooctyne moiety, which is critically discussed
Machine learning for accelerated bandgap prediction in strain-engineered quaternary III-V semiconductors
Quaternary III-V semiconductors are one of the major promising material
classes in optoelectronics. The bandgap and its character, direct or indirect,
are the most important fundamental properties determining the performance and
characteristics of optoelectronic devices. Experimental approaches screening a
large range of possible combinations of III- and V-elements with variations in
composition and strain are impractical for every target application. We present
a combination of accurate first-principles calculations and machine learning
based approaches to predict the properties of the bandgap for quaternary III-V
semiconductors. By learning bandgap magnitudes and their nature at density
functional theory accuracy based solely on the composition and strain features
of the materials as an input, we develop a computationally efficient yet highly
accurate machine learning approach that can be applied to a large number of
compositions and strain values. This allows for a computationally efficient
prediction of a vast range of materials under different strains, offering the
possibility for virtual screening of multinary III-V materials for
optoelectronic applications
Organosulfide Inhibitor Instigated Passivation of Multiple Substrates for Area-Selective Atomic Layer Deposition of HfO<sub>2</sub>
With
recent advancements in semiconductor technology, continuous
efforts are being made to meet the requirements for further reductions
in the feature sizes of electronic interconnects in semiconductor
devices. Efforts to improve area-selective deposition (ASD) processes
have led to researchers manipulating deposition surfaces using surface
inhibitors as tools for area-selective atomic layer deposition (AS-ALD).
In this study, organosulfide small-molecule inhibitors (SMIs) were
utilized for AS-ALD on metal, oxide, and nitride surfaces such as
Cu, SiO2, and TiN, respectively. Upon high-temperature
exposure, the organosulfide SMI decomposes to assist the adsorption
of its fragmentation products on the Cu and SiO2 substrates,
thereby simultaneously adsorbing and passivating the two surfaces
upon SMI exposure. The surface chemistry and reactivity were explained
by calculations using density functional theory with the slab approach
and Monte Carlo simulations. Furthermore, the blocking potential of
the SMIs was evaluated using atomic layer deposition (ALD) of HfO2. The SMI-covered Cu substrate showed inhibition against ALD
growth of HfO2 with a selectivity of approximately 98%
over 25 growth cycles compared to the uncovered Cu substrate successfully
blocking approximately 3 nm of HfO2 ALD. The SMI-covered
SiO2 substrate showed a lowered selectivity compared to
the SMI-covered Cu substrate but still, a substantial selectivity
was present compared to bare SiO2 and TiN substrates where
no blocking was observed. These results agree with the theoretical
findings. This possibility to block two important surfaces in semiconductor
manufacturing (Cu and SiO2) while leaving a third one (TiN)
unblocked for ALD growth is an important step for the future application
of ASD in the production of ever smaller semiconductor devices