Selective Photochemical Dry Etching of Compound Semiconductors: Enhanced Control Through Secondary Electronic Properties

1988 ◽  
Vol 129 ◽  
Author(s):  
Carol I. H. Ashby
Keyword(s):  
Quantum Yield ◽  
Band Gap ◽  
Electronic Properties ◽  
Compound Semiconductors ◽  
Dry Etching ◽  
Band Gap Energy ◽  
Carrier Generation ◽  
Gap Energy ◽  
Free Carriers ◽  
Carrier Recombination

ABSTRACTWhen laser-driven etching of a semiconductor requires direct participation of photogenerated carriers, the etching quantum yield will be sensitive to the electronic properties of a specific semiconductor material. The band-gap energy of the semiconductor determines the minimum photon energy needed for carrier-driven etching since sub-gap photons do not generate free carriers. However, only those free carriers that reach the reacting surface contribute to etching and the ultimate carrier flux to the surface is controlled by more subtle electronic properties than the lowestenergy band gap. For example, the initial depth of carrier generation and the probability of carrier recombination between the point of generation and the surface profoundly influence the etching quantum yield. Appropriate manipulation of process parameters can provide additional reaction control based on such secondary electronic properties. Applications to selective dry etching of GaAs and related materials are discussed here.

Density Functional Theory (DFT) Study: Electronic Properties of Silicene under Uniaxial Strain as H2S Gas Sensor

2016 ◽  
Vol 675-676 ◽  
pp. 15-18 ◽  
Author(s):  
Sasfan Arman Wella ◽  
Irfan Dwi Aditya ◽  
Triati Dewi Kencana Wungu ◽  
Suprijadi
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Band Gap Energy ◽  
Engineering Strain ◽  
Functional Theory ◽  
First Principle Calculation ◽  
Gap Energy ◽  
Center Configuration ◽  
Structural And Electronic Properties

First principle calculation is performed to investigate structural and electronic properties of strained silicene (silicon analogue of graphene) when absorbing the hydrogen sulfide molecule gas. Two configuration of silicene-H2S system, center and hollow configuration, is checked under 0% (pure), 5%, and 10% uniaxial engineering strain. We report that the silicene-H2S system in center configuration has larger binding energy compare to the silicene-H2S system in hollow configuration. The results show that H2S is physisorbed on silicene. In this work, we also find the change of band gap energy (~60 meV) is appearing when H2S interacted with silicene in center configuration, whereas the band gap energy of silicene has no change when interacted with H2S in hollow configuration.

Effect of Blending on the Enhancement of Electronic Properties of Biopolymers

2016 ◽  
Vol 13 (10) ◽  
pp. 6800-6802
Author(s):  
Naziha Suliman Alghunaim
Keyword(s):  
Hydrogen Bonding ◽  
Dipole Moment ◽  
Molecular Modeling ◽  
Band Gap ◽  
Electronic Properties ◽  
Band Gap Energy ◽  
The Other ◽  
Total Dipole Moment ◽  
Gap Energy ◽  
Chitosan Blends

Chitosan (Cs), gelatin (Gel) and starch (Str) are blended together to investigate the effect of blending upon the electronic properties of biopolymers. Three blends namely 25%, 50% and 75% of (Cs/Gel) and (Cs/Str) respectively. FTIR were utilized to ensure the occurrence of the proposed blend. The FTIR spectra show the occurrence of hydrogen bonding which indicated that the assigned blend is formed as a result of hydrogen bonding of NH2 and COOH terminals. Electronic properties are indicated with molecular modeling technique at PM6 semiemperical level. Modeling results indicate that, as far as starch and gelatin ratios increased in chitosan blends, the band gap energy is decreased in one hand while the total dipole moment is increased on the other hand.

scholarly journals Electronic properties of palladium diselenide by density functional theory

2017 ◽  
Vol 13 (3) ◽  
Author(s):  
Ying Xuan Ng ◽  
Rashid Ahmed ◽  
Abdullahi Lawal ◽  
Bakhtiar Ul Haq ◽  
Afiq Radzwan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Band Gap Energy ◽  
Partial Density ◽  
Full Potential ◽  
Functional Theory ◽  
Lattice Constants ◽  
Gap Energy

The knowledge of the structural and electronic properties of a material is important in various applications such as optoelectronics and thermoelectric devices. In this study, we are using full potential linearized augmented plane wave method framed within density functional theory provided by WIEN2k to optimize the structure of PdSe2 in orthorhombic (Pbca) phase and calculate its electronic properties. With the implementation of local density approximation (LDA), Perdew-Burke-Ernzerhof parameterization of generalized gradient approximation (PBE-GGA), Wu-Cohen parameterization of GGA (WC-GGA), and PBE correction for solid GGA (PBEsol-GGA), the computed results of lattice constants are found to be within 5% error with the experiment data. Also, our calculated indirect band gap energy was found to be ~0.24 eV by LDA along with modified Becke-Johnson potential functional (mBJ) with experimental lattice constants and ~0.52 eV by using PBE-GGA with optimized lattice constants. However, the effect of spin-orbit coupling is not found too much on the band gap energy. By analyzing the partial density of states, we identify that d-orbital of Pd is demonstrating a slightly more significant contribution to both the valence and conduction band near to Fermi level which is also in agreement with the previous first principles study.

scholarly journals Effect of hydration on the physical properties of glucose

2019 ◽  
Vol 9 (4) ◽  
pp. 4114-4118 ◽  
Keyword(s):  
Quantum Mechanics ◽  
Dipole Moment ◽  
Band Gap ◽  
Electronic Properties ◽  
Band Gap Energy ◽  
Molecular Electrostatic Potentials ◽  
Total Dipole Moment ◽  
Gap Energy ◽  
Homo Lumo ◽  
Electro Negativity

The effect of hydration on the electronic properties of glucose (Gl) is studied by quantum mechanics by using DFT procedures atB3LYP/6-31g(d,p). Total dipole moment, the highest and the lowest occupied molecular orbital (HOMO/LUMO band gap energy) and molecular electrostatic potentials (ESPs) are calculated at the same level of theory for all model molecules. The results indicated that there is an enhancement in the electronic properties of Gl where TDM of Gl is increased from2.5454Debye to 4.3157Debye while HOMO/LUMO band gap energy is decreased from 13.0994 eV to 3.2749 eV. Also, the calculated ESP results are indicated that the electro-negativity is increased due to hydration which means that the reactivity is increased and hence the electronic properties are improved.

Phase Transition and Electronic Properties of LiBH4 via First-Principles Calculations

2014 ◽  
Vol 971-973 ◽  
pp. 119-122
Author(s):  
Hai Ping Wang
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Band Gap Energy ◽  
First Principles Calculations ◽  
Volume Data ◽  
Functional Theory ◽  
Gap Energy ◽  
Phase Sequence

The transition phase and electronic properties of LiBH4 were investigated by ab initio plane-wave pseudopotential density functional theory method. According to the theoretical calculation, the phase sequence Pnma → P21/c → Cc is obtained. The phase transitions Pnma → P21/c and P21/c → Cc are at the pressure of 1.64 GPa and 2.83 GPa, respectively, by total energy-volume data. As the pressure increases, the value of the band gap energy is reduced from 7.1 (Pnma) to 6.1 eV (Cc). Moreover, the electronic properties of the high pressure phases are discussed. The electronic properties are linked to the band gap energy, total (partly) density of states and atoms (bond) populations.

Pressure-dependent modifications in the optical and electronic properties of Fe(IO3)3: The role of Fe 3d and I 5p lone-pair electrons

2021 ◽  
Author(s):  
Akun Liang ◽  
Placida Rodríguez-Hernandez ◽  
Alfonso Munoz ◽  
Saqib Raman ◽  
Alfredo Segura ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Band Gap ◽  
Electronic Properties ◽  
Lone Pair ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Optical And Electronic Properties ◽  
Indirect Band Gap ◽  
Lone Pair Electrons

We have determined by means of optical-absorption experiments that Fe(IO3)3 is an indirect band-gap material with a band-gap energy of 2.1 eV. This makes this compound the iodate with the...

scholarly journals Effect of Metal Oxides and Graphene Upon The Electronic Properties of Polyvinyl Alcohol

2021 ◽  
Author(s):  
Maroof A. Hegazy ◽  
Hend A. Ezzat ◽  
Ibrahim S. Yahia ◽  
Heba Y. Zahran ◽  
Hanan Elhaes ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Metal Oxides ◽  
Band Gap ◽  
Electronic Properties ◽  
Electrostatic Potential ◽  
Molecular Electrostatic Potential ◽  
Graphene Quantum Dots ◽  
Band Gap Energy ◽  
Electrical Characteristics ◽  
Gap Energy

Abstract Nanomaterials improve the physical and electronic characteristics of polymer matrices, allowing the matrices to be used as low cost, easy to handle sensors. Nano ZnO oxide is forming nanocomposite with PVA modified with graphene. Rather than ZnO other metal oxides are assumed to enhance the electronic properties of PVA modified with graphene (G). Accordingly, Density Function Theory (DFT) was used to analyze model molecules of Polyvinyl Alcohol (PVA) that improved with various metal oxides and graphene quantum dots (GQDs). To show the influence of nanomaterials on PVA matrix behavior, HOMO/LUMO molecular orbitals and Molecular Electrostatic Potential (MESP) mapping were calculated. The B3LYPL/LAN2DZ model was used to calculate the band gap energy ∆E, total dipole moment (TDM), and Molecular Electrostatic Potential (MESP). The obtained results indicated that PVA interacted with MgO, led to a significant improvement in the electrical characteristics. The incorporation of GQDs into PVA/MgO resulted in a novel nanocomposite with good electrical characteristics and a band gap energy ∆E of 0.201 eV, which is intended to be used as a humidity sensor.

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

Sign in / Sign up

Export Citation Format

Share Document