Electronic State and Piezoresistivity Analysis of Zinc Oxide Nanowires for Force Sensing Devices

2015 ◽  
Vol 644 ◽  
pp. 16-21 ◽  
Author(s):  
Koichi Nakamura
Keyword(s):  
Band Gap ◽  
Compressive Strain ◽  
Force Sensing ◽  
Wall Structure ◽  
Direct Band Gap ◽  
Direct Band ◽  
The Difference ◽  
Piezoresistance Coefficient ◽  
Indirect Band Gap ◽  
P Type

The piezoresistivity for force sensing in wurtzite-ZnO nanowires with [0001] orientation has been simulated on the basis of the first-principles calculations of model structures. According to the difference in wall structure, our devised nanowire models can be divided into three groups by their conductivities; no band-gap conducting models, direct band-gap semiconducting models, and indirect band-gap semiconducting models. The strain responses to carrier conductivity of n-or p-doped semiconducting wurtzite-ZnO[0001] nanowire models were calculated using band carrier densities and their corresponding effective masses derived from the one-dimensional band diagram by our original procedure for a small amount of carrier occupation. The conductivities of p-type direct band-gap models change drastically due to longitudinal uniaxial strain in the simulation: the longitudinal piezoresistance coefficient is 120 × 10–11 Pa–1 for p-type (ZnO)24 nanowire model with 1% compressive strain at room temperature.

scholarly journals Strain and Electric Field Modulated Indirect to Direct Band Transition of Monolayer GaInS2

2021 ◽  
Author(s):  
Atanu Betal ◽  
Jayanta Bera ◽  
Satyajit Sahu
Keyword(s):  
Optical Properties ◽  
Electric Field ◽  
Band Gap ◽  
Density Functional ◽  
Compressive Strain ◽  
Direct Band Gap ◽  
Td Dft ◽  
Direct Band ◽  
Band Transition ◽  
Indirect Band Gap

Abstract Strain and electric field dependent electronic and optical properties have been calculated using density functional theory (DFT) and time-dependent DFT (TD-DFT) for GaInS2 monolayer. GaInS2 monolayer shows an indirect band gap of 1.79 eV where valance band maxima (VBM) and conduction band maxima (CBM) rest between K and Γ point and at Γ point, respectively. Under a particular tensile strain (8%), a phase change from semiconductor to semimetal has been noticed. While at 4% compressive strain, the material changes from indirect to direct band gap of 2.22 eV having VBM and CBM at Γ point. With further increase in compressive strain, CBM shifted from Γ to M point, which leads to an indirect band gap again. The electric field also affects the band structure of monolayer GaInS2 and shows the transition between indirect to direct band gap at positive electric field of 4 V/nm, which acts normal to the surface. The strain-dependent optical properties are also calculated, which suggests that the absorption coefficient increases with compressive strain.

scholarly journals Transparent All-Oxide Hybrid NiO:N/TiO2 Heterostructure for Optoelectronic Applications

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 988
Author(s):  
Chrysa Aivalioti ◽  
Alexandros Papadakis ◽  
Emmanouil Manidakis ◽  
Maria Kayambaki ◽  
Maria Androulidaki ◽  
...  
Keyword(s):  
Band Gap ◽  
Single Phase ◽  
Structural Disorder ◽  
Energy Band Gap ◽  
Nitrogen Doped ◽  
Nio Thin Film ◽  
Direct Band ◽  
Output Characteristics ◽  
Indirect Band Gap ◽  
P Type

Nickel oxide (NiO) is a p-type oxide and nitrogen is one of the dopants used for modifying its properties. Until now, nitrogen-doped NiO has shown inferior optical and electrical properties than those of pure NiO. In this work, we present nitrogen-doped NiO (NiO:N) thin films with enhanced properties compared to those of the undoped NiO thin film. The NiO:N films were grown at room temperature by sputtering using a plasma containing 50% Ar and 50% (O2 + N2) gases. The undoped NiO film was oxygen-rich, single-phase cubic NiO, having a transmittance of less than 20%. Upon doping with nitrogen, the films became more transparent (around 65%), had a wide direct band gap (up to 3.67 eV) and showed clear evidence of indirect band gap, 2.50–2.72 eV, depending on %(O2-N2) in plasma. The changes in the properties of the films such as structural disorder, energy band gap, Urbach states and resistivity were correlated with the incorporation of nitrogen in their structure. The optimum NiO:N film was used to form a diode with spin-coated, mesoporous on top of a compact, TiO2 film. The hybrid NiO:N/TiO2 heterojunction was transparent showing good output characteristics, as deduced using both I-V and Cheung’s methods, which were further improved upon thermal treatment. Transparent NiO:N films can be realized for all-oxide flexible optoelectronic devices.

Optical Studies of Poly (N-Carbazole) (PVK) Blending with Polyvinylpyrrolidone (PVP) Using Tauc/Davis-Mott Model

2013 ◽  
Vol 652-654 ◽  
pp. 527-531 ◽  
Author(s):  
A.N. Alias ◽  
T.I. Tunku Kudin ◽  
Z.M. Zabidi ◽  
M.K. Harun ◽  
Ab Malik Marwan Ali ◽  
...  
Keyword(s):  
Band Gap ◽  
Urbach Energy ◽  
Quartz Substrate ◽  
Optical Studies ◽  
Direct Band Gap ◽  
Mott Model ◽  
Blended Polymer ◽  
Electronic Parameters ◽  
Direct Band ◽  
Indirect Band Gap

The optical absorption spectra of blended poly (N-carbazole) (PVK) with polyvinylpyrrolidone (PVP) in various compositions are investigated. A doctor blade technique was used to coat the blended polymer on a quartz substrate. The electronic parameters such as absorption edge (Ee), allowed direct band gap (Ed), allowed indirect band gap (Ei), Urbach edge (Eu) and steepness parameter (γ) were calculated using Tauc/Davis-Mott Model. The results reveal that the Ee, Ed and Ei increase with increasing of PVP ratio. There also have variation changing in Urbach energy and steepness parameter.

scholarly journals Biaxial strain modulated the electronic structure of hydrogenated 2D tetragonal silicene

RSC Advances ◽  
2019 ◽  
Vol 9 (72) ◽  
pp. 42245-42251
Author(s):  
Haoran Tu ◽  
Jing Zhang ◽  
Zexuan Guo ◽  
Chunyan Xu
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Biaxial Strain ◽  
Direct Band Gap ◽  
Direct Band ◽  
Indirect Band Gap

Hydrogenation can open the band gap of 2D tetragonal silicene, α-SiH is semiconductors with a direct band gap of 2.436 eV whereas β-SiH is indirect band gap of 2.286 eV. The band gap of α-SiH, β-SiH and γ-SiH can be modulated via biaxial strain.

LASER-INDUCED MULTIPHOTON PHOTOCONDUCTIVITY IN DIRECT AND INDIRECT BAND GAP CRYSTALS USING Z-SCAN TECHNIQUE

2009 ◽  
Vol 23 (23) ◽  
pp. 2783-2789 ◽  
Author(s):  
ARUN GAUR ◽  
D. K. SHARMA ◽  
K. S. SINGH ◽  
NAGESHWAR SINGH
Keyword(s):  
Absorption Coefficient ◽  
Band Gap ◽  
Laser Pulses ◽  
Beam Waist ◽  
Photon Absorption ◽  
Nanosecond Laser ◽  
Direct Band Gap ◽  
Direct Band ◽  
Nanosecond Laser Pulses ◽  
Indirect Band Gap

Nanosecond laser pulses have employed the photoconductive Z-scan technique. Photoconductivity traces measured by moving the sample across the laser beam waist were used for measuring two and three-photon absorption processes. The value of the three-photon absorption coefficient β3=9.6×10-10 cm 3/ GW 2 in the case of direct, and 8.96×10-12 cm 3/ GW 2 and 5.0×10-12 cm 3/ GW 2 in the case of indirect band gap crystals have been estimated from a comparison of traces measured by exciting the sample with the first and second harmonics of Nd : YAG laser. The low value of β3 in the case of indirect band gap crystals compared to direct band gap crystals is attributed to phonon-assisted transitions.

SHIFT OF BAND GAP FROM DIRECT TO INDIRECT AND OPTICAL RESPONSE OF LiF UNDER PRESSURE

2013 ◽  
Vol 27 (09) ◽  
pp. 1350061 ◽  
Author(s):  
A. SAJID ◽  
G. MURTAZA ◽  
A. H. RESHAK
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Lithium Fluoride ◽  
Pressure Range ◽  
Pressure Effect ◽  
Indirect Transition ◽  
Direct Band Gap ◽  
Direct Band ◽  
Indirect Band Gap

We hereby are reporting the transition pressure at which lithium fluoride ( LiF ) compound transforms from direct band gap to indirect band gap insulator on the basis of FP-LAPW calculations. The fundamental band gap of LiF compound suffers direct to indirect transition at a pressure of 70 GPa. The study of the pressure effect on the optical properties e.g. dielectric function, reflectivity, refractive index and optical conductivity of LiF in the pressure between 0–100 GPa, shows that this pressure range is very critical for LiF compound as there are significant changes in the optical properties of this compound.

Single pot synthesis of indirect band gap 2D CsPb2Br5 nanosheets from direct band gap 3D CsPbBr3 nanocrystals and the origin of their luminescence properties

Nanoscale ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 4001-4007 ◽  
Author(s):  
Paribesh Acharyya ◽  
Provas Pal ◽  
Pralok K. Samanta ◽  
Arka Sarkar ◽  
Swapan K. Pati ◽  
...  
Keyword(s):  
Band Gap ◽  
Luminescence Properties ◽  
Direct Band Gap ◽  
Amine Complexes ◽  
Lead Bromide ◽  
Direct Band ◽  
Indirect Band Gap

The origin of the luminescence properties of CsPb2Br5 is ascribed to the presence of different amorphous lead bromide amine complexes.

Carbon nanotube: An indirect ~ 0 eV band gap material

2016 ◽  
pp. 3546-3550
Author(s):  
Maheshwar Sharon ◽  
S. S. Kawale ◽  
Rakesh Afre ◽  
Madhuri Sharon ◽  
C. H. Bhosale
Keyword(s):  
Thin Film ◽  
Carbon Nanotube ◽  
Band Gap ◽  
Carrier Concentration ◽  
Hydrogen Atmosphere ◽  
Sem Analysis ◽  
Direct Band Gap ◽  
Direct Band ◽  
Indirect Band Gap ◽  
First Time

Thin film of carbon was synthesized from camphor (C10H16O) by CVD technique in hydrogen atmosphere. For the first time it is confirmed the presence of almost zero indirect band gap in addition to its direct band gap.. Carrier concentration with intrinsic carbon is found to be around 1021 n/cm3. It is suggested that unless the zero indirect band gap is  increased carbon thin film   cannot be used for making a p:n junction. XRD, Raman and SEM analysis are performed.

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