Shift Of Band Edge Research Articles

Magnetism-Induced Band-Edge Shift as the Mechanism for Magnetoconductance in CrPS4 Transistors.

Transistors realized on the 2D antiferromagnetic semiconductor CrPS4 exhibit large magnetoconductance due to magnetic-field-induced changes in the magnetic state. The microscopic mechanism coupling the conductance and magnetic state is not understood. We identify it by analyzing the evolution of the parameters determining the transistor behavior─carrier mobility and threshold voltage─with temperature and magnetic field. For temperatures T near the Néel temperature TN, the magnetoconductance originates from a mobility increase due to the applied magnetic field that reduces spin fluctuation induced disorder. For T ≪ TN, instead, what changes is the threshold voltage, so that increasing the field at fixed gate voltage increases the density of accumulated electrons. The phenomenon is explained by a conduction band-edge shift correctly predicted by the ab initio calculations. Our results demonstrate that the band structure of CrPS4 depends on its magnetic state and reveal a mechanism for magnetoconductance that had not been identified earlier.

Thermally tunable GeSi electro-absorption modulator with a wide effective operating wavelength range

We demonstrate a GeSi electro-absorption modulator with on-chip thermal tuning for the first time, to the best of our knowledge. Theoretical simulation proves that the device temperature can be tuned and the effective operating wavelength range can be broadened. When the heater power is 4.63 mW, the temperature of the waveguide increases by about 27 K and the theoretical operating wavelength range is broadened by 23.7 nm. The experimental results show that the optical transmission line shifted to the longer wavelength by 4.8 nm by every 1 mW heater power. The effective static operating wavelength range of the device is increased from 34.4 nm to 60.1 nm, which means it is broadened by 25.7 nm. The band edge shift coefficient of 0.76 nm/K is obtained by temperature simulation and linear fitting of the measured data. The device has a 3 dB EO bandwidth of 89 GHz at 3 V reverse bias, and the eye diagram measurement shows a data rate of 80 Gbit/s for non-return-to-zero on–off keying modulation and 100 Gbit/s for 4 pulse amplitude modulation in the 1526.8 nm to 1613.2 nm wavelength range as the heater power increases from 0 mW to 10.1 mW.

Bandgap narrowing and hole self-trapping reduction in Ga2O3 by Bi2O3 alloying

Ga2O3 is an emerging material with attractive electrical properties for improving the performance of high-voltage power electronics, and it is widely accepted that engineering its band edge energies will expand its applications, especially for bipolar devices. In this work, monoclinic phase (BixGa1−x)2O3 ternary alloys are fabricated on c-plane sapphire via magnetron co-sputtering of Ga2O3 and Bi2O3. The bandgap of Ga2O3 is found to decrease from 4.97 to 4.78 eV by alloying with a Bi x-fraction of 0.04, consistent with the theoretical prediction that alloying with Bi2O3 causes the up-shift of the valence band. Concurrent temperature-resolved cathodoluminescence (CL) measurements of the Ga2O3 and (Bi0.04Ga0.96)2O3 are employed to investigate their intrinsic ultraviolet (UV) luminescence and defect-related visible bands with increasing temperature from 80 K. The CL results reveal a more rapid thermal quenching of the self-trapped hole (STH) emission with an activation energy of only 32 meV, suggesting that alloying with Bi2O3 lowers the self-trapping energy for holes. Temperature-dependent electrical measurements reveal the conductivity of the (Bi0.04Ga0.96)2O3 film is one order of magnitude lower than that of the undoped Ga2O3 counterpart; however, both possess an electrical activation energy of ∼ 26 meV, likely associated with an impurity-related shallow donor. The low electrical conductivity of (Bi0.04Ga0.96)2O3 can be attributed to the compensation of shallow donors by acceptors activated by the Bi2O3-induced upward shift of the valence band edge. The frequency-dependent conduction and ionic polarization mechanisms up to 107 Hz are found to be identical for Ga2O3 and (Bi0.04Ga0.96)2O3, indicating that the conduction in this ternary alloy does not involve the activation of Bi acceptors.

Enhanced Photovoltaic Property and Panchromatic Photocatalytic by Forming D‐π‐A‐Bacteriochlorin Dyads: A Computational Investigation

The photovoltaic characteristics and panchromatic photocatalysis based on monomers and bithiophene‐chlorophyll dyads is investigated. The optical properties and the electron transport capacity of the titled dyes are explicated by investigating the geometry, electronic structure, electron injection, and recombination, intramolecular charge transfer, regeneration process, dye aggregation, and light‐harvesting. The results manifest that the original 3,3′‐dithioalkyl‐2,2′‐bithiophene (SBT)‐based molecule behaves better with photovoltaic performance and an enhanced JSC and VOC. For molecular design, the designed dyads not only show the enhanced absorption range and prolonged excited lifetimes but also noticeable electron transfer ability. Moreover, the strong interfacial interaction, fast electron transfer process, long recombination distance, inhibition in dye aggregate, enhanced regenerative interaction energy are elucidated, which is beneficial for a better photocurrent response. However, the slight shift of the conduction band edge in dyads significantly reduces the VOC, especially for SBT‐Chl. Among dyads, SBT‐BChl exhibits outstanding photovoltaic performance of 14%. Besides, photocatalysis analysis manifests that the dyad composites behave with red‐shifted spectra, enhanced dipole moments, better interfacial interaction to ensure electron transfer, which significantly improved the photocatalytic performance of TiO2. Our study is expected to offer theoretical guidelines for further screening the promising D‐π‐A‐bacteriochlorin dyads in photoelectric functional materials.

The MoS2-Graphene-Sapphire Heterostructure: Influence of Substrate Properties on the MoS2 Band Structure

Van der Waals MoS2/graphene heterostructures are promising candidates for advanced electronics and optoelectronics beyond graphene. Herein, scanning probe methods and Raman spectroscopy were applied for analysis of the electronic and structural properties of monolayer (ML) and bilayer 2H-MoS2 deposited on single-layer graphene (SLG)-coated sapphire (S) substrates by means of an industrially scalable metal organic chemical vapor deposition process. The SLG/S substrate shows two regions with distinctly different morphology and varied interfacial coupling between SLG and S. ML MoS2 nanosheets grown on the almost free-standing graphene show no detectable interface coupling to the substrate, and a value of 2.23 eV for the MoS2 quasiparticle bandgap is determined. However, if the graphene is involved in hydrogen bonds to the hydroxylated sapphire surface, an increased MoS2/graphene interlayer coupling results, marked by a shift of the conduction band edge toward Fermi energy and a reduction of the ML MoS2 quasiparticle bandgap to 1.98 eV. The surface topography reveals a buckle structure of ML MoS2 in conformity with SLG that is used to determine the dependence of the ML MoS2 bandgap on the interfacial spacing of this heterostructure. In addition, an in-gap acceptor state about 0.9 eV above the valence band minimum of MoS2 has been observed on locally elevated positions on both SLG/S regions, which is attributed to local bending strain in the grown MoS2 nanosheets. These fundamental insights reveal the impact of the underlying substrate on the topography and the band alignment of the ML MoS2/SLG heterostructure and provide the possibility for engineering the quasiparticle bandgap of ML MoS2/SLG grown on controlled substrates that may impact the performance of electronic and optoelectronic devices therewith.

Post-Ammonia-Treated V2CTx MXene at Different Pressures: Effects on Morphology, Electronic, and Optical Properties

In the present work, vanadium carbide (V2CTx) MXene was synthesized successfully and then treated with an ammonia solution (NH4OH) under different pressures using a hydrothermal process. The sample morphology reveals that the V2CTx MXene gradually changed from uneven multilayered micrometre-size sheets to uniform few-layered nanometer-size sheets as the pressure increased. The optical emission spectra show broad emission and a blue shift due to nitrogen-related defects and quantum confinement. X-ray photoelectron spectroscopy shows the presence of nitrogen in all of the samples. The ultraviolet photoelectron spectroscopy study shows a modified density of states near the Fermi level and a maximum of ∼0.6 eV valence band edge shift towards a higher binding energy side after post-treatment with ammonia. More interestingly, the E1g Raman band becomes degenerate and the E1g band upshifts (∼15 cm–1) with increasing pressure treatment. The Raman results suggest that the induced lattice strain due to post-ammonia treatment plays a crucial role in deciding the optical and electronic properties.

Band Alignment of 2D Material–Water Interfaces

Two-dimensional (2D) materials are presently being extensively studied in photo(electro)catalysis due to their excellent light absorption, high specific surface area, and readily tunable electronic properties. Electronic structure calculations are of great importance for improving our understanding of the activities of 2D materials. In this work, we perform density functional theory based molecular dynamics (DFTMD) simulations to simulate the explicit 2D material–water interfaces and study the water effects on band gaps and band edge positions in detail. Nine 2D materials with three kinds of typical surface structures are considered, including BN, MoS2, WS2, Black-P, GaSe, GaTe, CrCl3, MoO3, and V2O5. We find that the band gap will decrease when interacting with water, which is induced by a combination of structural and electronic effects. Especially, overlaps between electron densities of solid surfaces and liquid water molecules may change the band gap significantly. The band edge shifts are mainly determined by the net orientation of water molecules at the interfaces. More importantly, our results show that water dipoles are related to surface structures and may not be negligible. Our findings emphasize the water effects on electronic structures and pave the way to screen low-cost and high-efficiency 2D material photocatalysts.

Continuously broken ergodicity and reversible photo-darkening in As-Ch glass

The exact mechanism responsible for reversible photo-darkening in As-Ch glasses has been an open question. Many mechanisms have been suggested. Here I assume that self trapped excitons (STE) cause a local structural relaxation and end up in mid band states. I show that such an excitonic state produces a local frustration field which distorts the lattice. These states most probably decay non-radiatively through excitation of localized modes satisfying quantum statistics. I posit that these localized modes are the result of continuously broken ergodicity. These modes can channel to form local oscillations, which would act to raise the temperature, or couple to the valence electronic energy, which results in a local structural modification. I show the observed temperature dependence of both the band edge shift and the volume increase are predicted by the latter mechanism.

Amine Hole Scavengers Facilitate Both Electron and Hole Transfer in a Nanocrystal/Molecular Hybrid Photocatalyst

A well-known catalyst, fac-Re(4,4'-R2-bpy)(CO)3Cl (bpy = bipyridine; R = COOH) (ReC0A), has been widely studied for CO2 reduction; however, its photocatalytic performance is limited due to its narrow absorption range. Quantum dots (QDs) are efficient light harvesters that offer several advantages, including size tunability and broad absorption in the solar spectrum. Therefore, photoinduced CO2 reduction over a broad range of the solar spectrum could be enabled by ReC0A catalysts heterogenized on QDs. Here, we investigate interfacial electron transfer from Cd3P2 QDs to ReC0A complexes covalently bound on the QD surface, induced by photoexcitation of the QD. We explore the effect of triethylamine, a sacrificial hole scavenger incorporated to replenish the QD with electrons. Through combined transient absorption spectroscopic and computational studies, we demonstrate that electron transfer from Cd3P2 to ReC0A can be enhanced by a factor of ∼4 upon addition of triethylamine. We hypothesize that the rate enhancement is a result of triethylamine possibly altering the energetics of the Cd3P2-ReC0A system by interacting with the quantum dot surface, deprotonation of the quantum dot, and preferential solvation, resulting in a shift of the conduction band edge to more negative potentials. We also observe the rate enhancement in other QD-electron acceptor systems. Our findings provide mechanistic insights into hole scavenger-quantum dot interactions and how they may influence photoinduced interfacial electron transfer processes.

Investigation into complex defect properties of near-stoichiometric Cu2ZnSnSe4 thin film

In this work, a systematic investigation of the effects of point defects on the efficiency of a Cu2ZnSnSe4 (CZTSe) thin film solar cell was conducted using temperature-/power-dependent photoluminescence (PL) and time-resolved photo-luminescence (TRPL). The studied stoichiometric CZTSe absorber layer for a CZTSe solar cell with an efficiency of 4.4 % was prepared using the low-toxicity selenization process. The fitting to the Arrhenius plot and the stretched tail at the long-wavelength side of PL spectrum obtained at 10 K indicated a high concentration of zinc on copper (CuZn) point defects. The dispersive-photon-energy-dependent TRPL at 10 K exhibited non-exponential stretched PL decay at all photon energies and, in particular, revealed the highly fluctuating potential of CZTSe that caused carrier localization. This effect was observed to be caused by [2CuZn− + SnZn2+] defect clusters, which produce a significant conduction/valence band-edge shift in their vicinity in CZTSe and can cause shunt leakage and an increase in series resistance. This systematic investigation presents the experimental characterization of [2CuZn− + SnZn2+] defect clusters and provides perspective to help clarify the performance deterioration of CZTSe solar cells.

Formation of a one-dimensional hole channel in MoS2 by structural corrugation

We have investigated the energetics and electronic structure of monolayer MoS2 with periodic structural corrugations by density functional theory. The total energy of corrugated MoS2 slightly increases with increasing corrugation height, which indicates that the MoS2 sheet intrinsically and extrinsically possesses nanometer scale structural corrugation. The corrugation causes an upward shift of the valence band edge and a downward shift of the conduction band edge owing to the local strain at the wrinkle peak. Accordingly, by injecting holes using the external electric field, the corrugation leads to a one-dimensional conducting channel in the MoS2 sheet. This indicates that corrugation is a plausible procedure to control the dimensionality of the electrons and holes in two-dimensional materials without implementing one-dimensional boundary conditions.

Electron–phonon effects and temperature-dependence of the electronic structure of monoclinic β-Ga2O3

Gallium oxide (Ga2O3) is a promising semiconductor for next-generation high-power electronics due to its ultra-wide bandgap and high critical breakdown field. To utilize its unique electrical properties for real-world applications, an accurate description of its electronic structure under device-operating conditions is required. Although the majority of first-principles models focus on the ground state, temperature effects govern the key properties of all semiconductors, including carrier mobility, band edge positions, and optical absorption in indirect gap materials. We report on the temperature-dependent electronic band structure of β-Ga2O3 in a wide temperature range from T = 0 to 900 K using first-principles simulations and optical measurements. Band edge shifts from lattice thermal expansion and phonon-induced lattice vibrations known as electron–phonon renormalization are evaluated by utilizing the quasi-harmonic approximation and the recently developed “one-shot” frozen phonon method, respectively. Electron–phonon effects and thermal expansion together induce a substantial temperature-dependence on the bandgap, reducing it by more than 0.5 eV between T = 0 and 900 K, larger than that observed in other wide bandgap materials. Key implications, including an increase in carrier concentrations, a reduction in carrier mobilities due to localization of band edge states, and an ∼20% reduction in the critical breakdown field, are discussed. Our prediction of temperature-dependent bandgap matches very well with experimental measurements and highlights the importance of accounting for such effects in first-principles simulations of wide bandgap semiconductors.

Triphenylphosphine assisted phosphorization of g-C3N4 for enhanced photocatalytic activity

It is an effective strategy to regulate the structure of photocatalysts for enhanced photocatalytic hydrogen evolution. In this work, a facile method was developed to introduce P atoms into g-C3N4via the thermal calcination treatment. In contrast to pristine g-C3N4, the obtained P-CN(PPh3) exhibited a negative shift of conduction band edge with enhanced light absorption after the introduction of P atoms into g-C3N4, thus benefiting the photocatalytic hydrogen evolution. Moreover, the introduction of P element in g-C3N4 can also improve the charge separation during the photocatalytic hydrogen reaction, significantly accelerating the photocatalytic hydrogen production rate of P-CN(PPh3).

Cation doped approach for photodegradation of 4-chlorophenol by highly efficient solar active NiS photocatalyst: The case of Cu2+ doping

This study reports an efficient photodegradation of 4-chlorophenol using Cu2+ doped nickel sulfide (NiS) nanoparticles. Our study provides a facile method to synthesize Cu2+ doped NiS nanoparticles by partial polyol method and structurally validates the formation of single phased random-shaped particles. Cu2+ doping in NiS matrix results in a red shift of the absorption band edge, thus lowering the band gap from 3.62 to 2.98 eV and creating electron trapping centers that prevent electron-hole recombination. The presence of such electron trapping centers was attributed to oxygen vacancies which were justified from the appearance of g-signal in electron paramagnetic resonance analysis. Photodegradation study of 4-chlorophenol by Cu2+ doped NiS nanoparticles under ambient solar light showed significant improvement in degradation efficiency up to 90 % as compared to 19 % for undoped NiS nanoparticles. Furthermore, increased degradation efficiency was also backed by total organic carbon (TOC) analysis of the mineralization ability of Cu2+ doped NiS nanoparticles. Moreover, scavenging trapping analysis showed holes, ⋅OH and superoxide radicals as reactive oxidative species (ROS) primarily responsible for increased photodegradation efficiency. Thus, the synthesized Cu doped NiS nanoparticles proved to be an efficient catalyst, which could be used as a potential candidate for industrial photocatalytic applications under ambient solar light.

Influence of self-doping on band-edges and Fermi energy of CsPbBr3

The electronic properties of CsPbBr 3 thin films cast through a solution route are known to depend on the stoichiometry of the precursors. In this work, with the aid of Kelvin probe force microscopy (KPFM) and scanning tunneling spectroscopy (STS) studies, a complete energy landscape has been derived for the all-inorganic perovskite formed with a wide range of precursor stoichiometries. While the optical band gap of the perovskite is known to remain unchanged with a variation in the stoichiometry, we show the manner in which their Fermi energy, valence band (VB), and conduction band (CB) edges shift. The variation in the energy levels has been correlated to the presence of defects. Since the formation energy of different intrinsic point defects depends on the growth environment, the nature of defects has depended on the precursor stoichiometry used during the formation of the perovskites. The presence of defects has thereby tuned the Fermi energy and the type of electronic conductivity in CsPbBr 3 as well. Here, the CB and VB edges have responded due to the self-doping process. Finally, we have presented the energy landscape of the perovskite with a variation in the precursor stoichiometry, since the energy levels are indeed crucial in designing any optoelectronic devices based on CsPbBr 3 . • Fermi level and band edges of CsPbBr 3 are affected by the precursor stoichiometry. • Energy landscape of the perovskite derived from a combination of KPFM and STS. • CsPbBr 3 formed with CsBr-rich precursors has p -type conductivity. • CsPbBr 3 formed with PbBr 2 -rich growth condition exhibits an n -type behavior. • Bands moved away from vacuum level in perovskites formed in PbBr 2 -rich environment.

Facile in situ construction of novel hybrid 3D-BiOCl@PDA heterostructures with vacancy induced charge transfer for efficient visible light driven photocatalysis and antibacterial activity

Combining a wide band BiOCl semiconductor with organic π-conjugated systems is critical for increasing its light absorption and charge carrier mobility at heterojunction interfaces for efficient photocatalysis. In this study, we described a bioinspired dopamine-assisted one-pot route as an environmentally benign method to construct multifunctional in situ hybrid 3D-BiOCl@PDA heterostructure photocatalysts in an aqueous medium under mild conditions. The versatile role of dopamine was utilized for the controlled integration of 3D-BiOCl (001) hierarchical microspheres while simultaneously modified their surfaces with thin layers of PDA via its in situ polymerization. TGA, UVDRS, and XPS revealed that PDA thickness and its cooperative chelating effect with BiOCl nanosheet at a hybrid interface allowed effective charge transfers, and band-edge shift, induced oxygen defects for extended visible light absorptions. The resulting hybrids exhibited evidently multifunctional photocatalytic performance for complete RhB dye removal (12 times), enhanced selective benzyl alcohol oxidation (>99 benzaldehyde) and excellent antibacterial activity against Staphylococcus aureus (99.9%) than bare BiOCl under identical conditions. Furthermore, the hybrids showed excellent photostability and recyclability for up to five reaction cycles. These highly enhanced results are attributed to their 3D-structural features and close contact between PDA and BiOCl. Based on the results of active species experiments and ESR spectral analysis a possible Z-scheme photocatalytic mechanism has been proposed for the hybrid heterostructure system. Hence, the present work is an effective noble metal-free strategy for creating novel hybrid BiOCl heterostructures with multifunctional properties for visible light photocatalytic applications.

Third order nonlinear optical absorption studies of Cr3+ doped PbWO4 nanostructures

We report the synthesis of Cr3+ doped PbWO4 nanoparticles with different concentration of Cr3+ through chemical method. The structural, morphological and optical characterization was studied through X-ray diffraction (XRD), Raman, UV–Visible spectra, Photoluminescence, X-ray photo electron spectroscopy (XPS) and Transmission electron Microscopy (HR-TEM). The XRD patterns revealed the tetragonal phase of stolzite and the peaks are highly crystalline structure with no segregation of Cr3+. UV–Vis absorption spectra reveal that the shift of absorption band edge towards higher wavelength upon doping of Cr3+ions. The average particle size of the nanostructure as revealed by the TEM image lies around 47 nm. Third order nonlinearity of Cr3+ doped PbWO4 nanoparticles were analysed by the standard Z-scan technique using 532 nm Nd: YAG laser. The observed nonlinear absorption (NLA) and nonlinear refraction (NLR) behavior is caused by thermal nonlinear effects due to localized heating. Experimental results have demonstrated that an increase in optical nonlinearity occurs with higher Cr3+ concentrations. Based on the observed nonlinearity it is suggested that the synthesized nanostructures could be used in various optical device applications.

Field-Effect Tuning of Electrochemistry at 2D Semiconductor Electrodes: Charge Transfer Kinetics Can be Modulated with a Back Gate Voltage

Semiconductor electrodes are widely used in electrocatalytic reactions. The ability to improve and modulate the heterogeneous charge transfer kinetics on semiconducting electrodes is a major challenge for the electrochemical application of these materials. Instead of changing the electronic occupation of the semiconductor by chemical doping, we adopt an electronic method to modulate band edge alignment and solution electrochemistry at 2D ZnO working electrodes.In our approach, a field-effect transistor with ultrathin ZnO semiconductor (3-5 nm) is fabricated, the heart of which is a metal-insulator-semiconductor (MIS) stack. A high-dielectric-constant material (HfO2) is used as the insulator to realize low-voltage tunability of the device. The ZnO layer of the device functions as the working electrode (WE) for electrochemical reactions. By applying a back gate voltage to this MIS field-effect transistor, charge carriers are electrostatically induced and the ZnO band edges shift at the front face of the ZnO in contact with electrolyte. These effects can be exploited to manipulate the charge transfer kinetics on the ZnO electrode at a given electrode potential. We demonstrate this by focusing on outer-sphere redox chemistry. In order to eliminate mass transfer effects, microfluidic flow cells are coupled to the ZnO devices. Steady state kinetic analysis is carried out to extract the electron transfer rate constant of the redox process as a function of both electrochemical and back gate potentials. The heterogeneous electron transfer rate can be tuned by over an order of magnitude using the back gate voltage. The work demonstrates that a back gate provides another degree of freedom in determining electrochemical reaction kinetics at ultrathin semiconductor working electrodes. The method also opens possibilities for control over a wider range of semiconductor electrochemistry, such as electrocatalytic reactions. Figure 1

Lattice strain and band overlap of the thermoelectric composite Mg2Si1−xSnx

${\mathrm{Mg}}_{2}{\mathrm{Si}}_{1\text{\ensuremath{-}}x}{\mathrm{Sn}}_{x}$ solid solutions show enhanced thermoelectric performance when the Sn mole fraction $x$ is approximately $x=0.7$. This has been discussed in terms of complexity of the electronic structure arising from the crossover of two bottom conduction bands, but direct detailed understanding of the origins and the precise nature of this band convergence is limited. Here, we report first-principles calculations of the band edge changes analyzed by band unfolding and crystal orbital Hamilton population techniques. We find that strain is particularly important at this crossing. ${\mathrm{Mg}}_{2}\mathrm{Si}$ and ${\mathrm{Mg}}_{2}\mathrm{Sn}$ show opposite trends in the conduction band edge shifts leading to a band crossover at $x\ensuremath{\sim}0.625$. However, there are also important effects due to disorder. Transport calculations show that enhancement of the figure of merit $ZT$ value owes to the combined effects of lattice strain, band edge overlap, composition change, and disorder.

Electro-optical properties of APS and APhS linkers on silicon thin film: A DFT study

APS (3-Aminopropyl) trimethoxysilane) and APhS (p-Aminophenyl) trimethoxysilane) are the most commonly used linkers on a silicon surface. We investigate the surface properties of the structures, including APS or APhS on a silicon substrate. The studied structures consist of APS or APhS linkers with one, two, or three bonds with a substrate, which is a thin layer of Si with crystal orientation 〈100〉 or 〈111〉. Using a first-principles study based on density functional theory (DFT), we investigated the electronic and optical properties of the silicon-linker interface, such as interface states, orbital location, dielectric function, and photon absorption. The effects of linker type, number of linker-substrate bonds, and crystal orientation on density of states are investigated as a most important electrical property. In addition, we calculated the orbital location and dielectric function in the structures consisting of the substrate with the linker molecules. In this study, we propose techniques to reduce band edge shifts due to surface states and enhance the current mobility in structures with APS or APhS on a silicon substrate. The obtained results show that the use of APS linker molecules instead of APhS can reduce the conduction band shift by up to 50% and the density of interface states are sharply reduced at a depth of approximately 5 Å from the silicon surface. Also, simulation results show that the effect of linkers on the dielectric function can be negligible in the case of using linkers with one or two bonds with the substrate at low energies (lower than 5 eV).