Optical Band Gaps and Electrical Conductance of Si Nanocrystals in SiO2 Matrix for Optoelectronic Applications

2013 ◽  
Vol 545 ◽  
pp. 134-140 ◽  
Author(s):  
Thipwan Fangsuwannarak ◽  
K. Khunchana ◽  
S.T. Rattanachan
Keyword(s):  
Silicon Oxide ◽  
Energy Gap ◽  
Electrical Conductance ◽  
Oxide Phase ◽  
Considerable Effect ◽  
Density Level ◽  
Optical Energy Gap ◽  
Force Microscopy ◽  
Tauc Plot ◽  
Si Nanocrystals

In this study, silicon nanocrystal (Si-nc) films were synthesized by compositing of Si-nc powder embedded in silicon oxide phase. The Si-nc film produced by the spin-coating methode using Tetraethylorthosilicate, ethanol, phosphoric acid, and Si-nc powder as suspension precursors. The variation in structural and optical properties of Si-nc sol films with the amounts of Si-nc powder have been characterized. Atomic force microscopy (AFM) shows that low density level of Si-nc power can result in the amount of porosity in the Si-nc films. It is found that when the Si-nc films have the higher Si-nc density, the small pores in the SiO2 phase were removed. In addition, optical energy gap (Eg) of Si-nc samples was evaluated by the Tauc plot method. It is a crucial attribute for a promising photonic device. The obtained optical bang gap values were extended from 1.10 eV to 1.40 eV as compared with the typical Si bulk. In addition, density of Si-nc clusters has a considerable effect on the electrical conductance of the Si-nc films measured at room temperature.

Charging effects in Si quantum dots for Non Volatile Memories applications monitored by Electrostatic Force Microscopy

2003 ◽  
Vol 794 ◽  
Author(s):  
R.A. Puglisi ◽  
G. Nicotra ◽  
S. Lombardo ◽  
C. Spinella ◽  
G. Ammendola ◽  
...  
Keyword(s):  
Silicon Oxide ◽  
Electrostatic Force ◽  
Chemical Vapour ◽  
Nanoscale Structures ◽  
Force Microscopy ◽  
Si Nanocrystals ◽  
Potential Applications ◽  
P Type ◽  
Mos Structures ◽  
Si Quantum Dots

ABSTRACTNanoscale structures have been recently proposed as charge storage nodes due to their potential applications for future nanoscale memory devices. Our approach is based on the idea of using Si nanodots as discrete floating gates. To experimentally investigate such potential, we have fabricated MOS structures with Si nanocrystals. The dots have been deposited onto an ultra-thin tunnel oxide by chemical vapour deposition, and then annealed at 1000 °C for 40 s, to crystallize all the dots. After deposition the dots have been covered by a CVD SiO2 layer, thus resulting in dots completely embedded in stoichiometric silicon oxide. The nanocrystal density and size have been studied by energy filtered TEM (EFTEM) analysis. An electrostatic force microscope has been used to locally inject the charge. By applying a relatively large tip voltage a few dots have been charged, and the shift in the tip phase has been monitored. The shift in the phase is attributed to the presence of the charge in the sample. A comparison between n and p type samples is also shown.

scholarly journals ESTIMASI CELAH ENERGI SENYAWA HASIL EKSTRAK DAUN SIRSAK (ANNONA MURICATA L.) MENGGUNAKAN METODE TAUC PLOT

2019 ◽  
Vol 4 (1) ◽  
pp. 48-51
Author(s):  
Marselinus E. Dandara ◽  
Redi Kristian Pingak ◽  
Albert Zicko Johannes
Keyword(s):  
Absorption Spectrum ◽  
Leaf Extract ◽  
Energy Gap ◽  
Annona Muricata ◽  
Optical Energy Gap ◽  
Optical Energy ◽  
Tauc Plot ◽  
Vis Spectroscopy ◽  
Viscous Solution

Abstrak  Dalam artikel ini, celah energi optik senyawa hasil ekstrak daun Annona Muricata L. diestimasi menggunakan metode Tauc plot. Daun sirsak yang diambil dari Kabupaten Sumba Barat Daya dikeringkan dan dihaluskan kemudian diekstraksi secara maserasi. Selanjutnya, hasil ekstrak ini dievaporasi untuk menghasilkan larutan kental ekstrak daun sirsak. Larutan kental ini kemudian diencerkan kembali untuk memperoleh larutan dengan konsentrasi 100 ppm, 200 ppm dan 300 ppm, yang selanjutnya dikarakterisasi menggunakan spektrofotometer UV-Vis. Spektrum serapan UV-Vis yang diperoleh kemudian dianalisis untuk menentukan celah energi optik senyawa hasil ekstrak daun sirsak. Dengan menggunakan metode Tauc plot, diperoleh nilai celah energi optik rata-rata sebesar 1,830 eV.  Kata kunci: celah energi; daun sirsak; spektroskopi UV-Vis, Tauc plot   Abstract  Estimation of energy gap of compounds extracted from Annona Muricata L. Leaves using Tauc Plot. In this article, optical energy gap of compounds from Annona Muricata L. leaves is estimated using Tauc plot. The leaves taken from Sumba Barat Daya are dried and mashed to become powder, which is then extracted by maceration. The extract is then evaporated to obtain a viscous solution of the leaf extract. The solution is further diluted to obtain solutions with concentration of 100 ppm, 200 ppm and 300 ppm. The solutions are then characterized using UV-Vis spectrophotometer. UV-Vis absorption spectrum obtained is then analyzed to obtain optical energy gap of the material. Using Tauc plot method, the average optical energy gap of the extract is found to be 1,830 eV Keywords: energy gap; Annona Muricata L; UV-Vis Spectroscopy; Tauc Plot

scholarly journals Structural and optical properties of tungsten doped TiO2 thin films fabricated by spray pyrolysis technique

2020 ◽  
Vol 2 (1) ◽  
pp. 1-8
Author(s):  
Tamilnayagam V ◽  
Keerthika Kumarasamy ◽  
Tamiloli Devendhiran ◽  
Mohanraj K ◽  
Ilavarasan L
Keyword(s):  
Thin Films ◽  
Spray Pyrolysis ◽  
Energy Gap ◽  
Spray Pyrolysis Technique ◽  
Amorphous Structure ◽  
Tio2 Thin Films ◽  
Optical Energy Gap ◽  
Force Microscopy ◽  
Atomic Force ◽  
Double Beam

The pure and tungsten doped titanium oxide WxTi1-xO2 (x=0, 0.1) thin films have been successfully deposited on the glass substrate at 400 °C using spray pyrolysis technique. The structural properties of the prepared films were characterized by X-Ray Diffraction (XRD). From the XRD spectrum, the sample shows the amorphous structure. Their surface morphology was probed using Scanning Electron Microscopy (SEM) and the mechanical properties, topography and surface roughness of the grown films was investigated by Atomic Force Microscopy (AFM). The functional group and optical characteristic of prepared films were analyzed by Fourier Transform Infra-Red (FT-IR) spectroscopy and UV-Vis-double beam spectrometer.  The optical energy gap was determined by transmittance measurement.

scholarly journals PENENTUAN CELAH ENERGI OPTIK EKSTRAK DAUN ALPUKAT (PERSEA AMERICANA MILL) ASAL DESA OINLASI MENGGUNAKAN METODE TAUC PLOT

2018 ◽  
Vol 3 (1) ◽  
pp. 86-90
Author(s):  
Magdalena M. Y. Missa ◽  
Redi K. Pingak ◽  
Hadi Imam Sutaji
Keyword(s):  
Energy Gap ◽  
Electronic Devices ◽  
Persea Americana ◽  
Indirect Transition ◽  
Direct Transition ◽  
Optical Energy Gap ◽  
Tauc Plot ◽  
Forbidden Transition ◽  
Alternative Materials

Abstrak Telah ditentukan celah energi optik ekstrak daun alpukat (Persea Americana Mill) asal Desa Oinlasi menggunakan metode Tauc plot. Penentuan nilai celah energi ditentukan untuk 3 kemungkinan jenis transisi yaitu direct transition, indirect transition, dan direct forbidden transition. Berdasarkan perhitungan menggunakan metode Tauc plot, celah energi rata-rata yang diperoleh untuk masing-masing transisi secara berturut-turut adalah 1,834 eV, 1,829 eV, dan 1,835 eV. Berdasarkan nilai celah energi senyawa hasil ekstrak daun alpukat dapat dikelompokkan sebagai bahan semikonduktor. Oleh karena itu, disimpulkan bahwa ekstrak daun alpukat berpotensi digunakan sebagai bahan alternatif piranti elektronik. Kata kunci : Daun alpukat, celah energi, semikonduktor, Tauc plot Abstract A study on determination optical energy gap of avocado leaves extract (Persea Americana Mill) from Oinlasi Village using Tauc plot method has been done. Determination of energy gap value was done for 3 possible transition types : direct transition, indirect transition, and direct forbidden transition. Based on calculations using Tauc plot method, energy gap average obtained for each transition are 1,834 eV, 1,829 eV, and 1,835 eV, respectively. Based on this energy gap value, the compound of avocado leaves extract can be categorized as a semiconducting material. Therefore, it can be concluded that avocado leaves extract has the potential to be used as alternative materials in electronic devices. Keywords : avocado leaves, energy gap, semiconductor, Tauc plot

scholarly journals Study on some linear and nonlinear optical parameters of glycine hydrofluoride single crystals

2018 ◽  
Vol 36 (4) ◽  
pp. 685-696 ◽  
Author(s):  
A. Abu El-Fadl ◽  
A.M. Abdel-Salam ◽  
A.M. Nashaat
Keyword(s):  
Refractive Index ◽  
Nonlinear Optical ◽  
Grown Crystal ◽  
Elevated Temperatures ◽  
Energy Gap ◽  
Second Harmonic ◽  
Interband Transition ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Tauc Plot

AbstractSingle crystal of glycine hydroflruoride (GHF) was grown from aqueous solution by slow evaporation technique. The structure of the grown crystal was tested and analyzed through X-ray powder diffraction. The functional groups have been identified from the FT-IR spectra. Slabs cut normal to the b-axis from the grown crystal were subjected to incident radiation with a wavelength range of 200 nm to 800 nm to investigate the transmittance and reflectance spectra. Linear optical parameters such as extinction coefficient k, refractive index n and both the real and imaginary parts: ∊real and ∊im of the dielectric permittivity were calculated as functions of the incident photon energy. The dispersion of the refractive index was fitted in terms of Cauchy formula and Wemple-DiDomenico single oscillator model. GHF crystals exhibited indirect optical interband transition and the optical energy gap Eg was determined by using Tauc plot. The indirect band gaps at elevated temperatures were determined and their temperature dependence was estimated. Optical band gap Eg values were found to decrease with an increase in crystal temperature; however, the band tail width exhibited opposite behavior. The nonlinear optical potential was examined by the second harmonic generation (SHG) test.

scholarly journals SYNTHESIS OF CARBON DOTS (CDS) AND DETERMINATION OF OPTICAL GAP ENERGY WITH TAUC PLOT METHOD

2021 ◽  
Vol 3 (2) ◽  
pp. 73-86
Author(s):  
Jumardin Jumardin ◽  
Akhiruddin Maddu ◽  
Koekoeh Santoso ◽  
Isnaeni Isnaeni
Keyword(s):  
Carbon Dots ◽  
Energy Gap ◽  
Indirect Transition ◽  
Optical Energy Gap ◽  
Time Duration ◽  
Optical Energy ◽  
Laser Ablation Method ◽  
Tauc Plot ◽  
Optical Gap Energy

Carbon Dots (CDs) which have been synthesized using the laser ablation method show the presence of UV-Vis absorption in the wavelength range of 303 nm to 333 nm for absorbance and 495 nm to 503 nm for fluorescence. Changes in the time duration 1, 2, 3 hours of CDs resulted in changes in the optical energy gap. The optical energy gap valuesare distinguished by the type of indirect transition (n=2) is 3.40 eV (1 hour), 3.15 eV (2 hour), 2.85 eV (3 hour) and direct transition (n=1/2) is 2.58 eV (1 hour), 2.31 eV (2 hour), 1.70 eV (1 hour).

Effect of the structural changes on the mechanical properties of the sintered films

2016 ◽  
Vol 12 (1) ◽  
pp. 4141-4144
Author(s):  
Garima Jain
Keyword(s):  
Crystallite Size ◽  
Lattice Constant ◽  
Structural Changes ◽  
Structural Investigation ◽  
Energy Gap ◽  
Lattice Parameter ◽  
Metal Chalcogenides ◽  
Optical Energy Gap ◽  
Tin Telluride ◽  
Physical Quantities

Polycrystalline films of tin telluride were prepared by sintering technique. The structural investigation of the films with different thicknesses enables to determine lattice parameter, crystallite size and strain existing in the films. The XRD traces showed that strain was tensile in nature. The crystallite size increases with thickness while strain decreases. Higher the value of tensile strain, larger is the lattice constant. The optical energy gap shows a descending nature with increasing strain and so with the lattice constant. Such an attempt made to delve into interdependence of basic physical quantities helps to explore the properties of SnTe and utilize it as an alternative to heavy metal chalcogenides in various technological applications.  

scholarly journals Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5970
Author(s):  
Nabil Al-Zaqri ◽  
Mohammed Suleiman ◽  
Anas Al-Ali ◽  
Khaled Alkanad ◽  
Karthik Kumara ◽  
...  
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Structural Parameters ◽  
Population Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Optical Energy Gap ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
Td Dft

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2–sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV–Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric–derivative thermogravimetric analysis, indicating its stability up to 95 °C.

High Temperature Annealing Behaviors of Luminescent Siox:H Films

1999 ◽  
Vol 560 ◽  
Author(s):  
Zhixun Ma ◽  
Xianbi Xiang ◽  
Shuran Sheng ◽  
Xianbo Liao ◽  
Chunlin Shao ◽  
...  
Keyword(s):  
High Temperature ◽  
Absorption Edge ◽  
Optical Transition ◽  
Stokes Shift ◽  
Transition Process ◽  
Ir Absorption ◽  
High Temperature Annealing ◽  
Force Microscopy ◽  
Atomic Force ◽  
Si Nanocrystals

ABSTRACTThe effects of high temperature annealing on the microstructure and optical properties of luminescent SiOx:H films have been investigated. Micro-Raman scattering and IR absorption, in combination with atomic force microscopy (AFM), provide evidence for the existence of both a-Si clusters in the as-grown a-SiOx:H and Si nanocrystals in the 1170°C annealed films. The dependence of optical coefficients (μ) on photon energy (hv) near the absorption edge (Eg) is found to follow the square root law: (μhv)½ μ (Eg – hv), indicating that nano-Si embedded in Si02 is still an indirect material. A comparison of the deduced absorption edge with the PL spectra shows an obvious Stokes shift, suggesting that phonons should be involved in the optical transition process.

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