New approach to the problem of determination of optical band gap of crystals with exponential absorption edge

1999 ◽  
Author(s):  
V. V. Bogoboyashchiy
2015 ◽  
Vol 42 ◽  
pp. 193-198 ◽  
Author(s):  
Mart-Mari Duvenhage ◽  
Martin Ntwaeaborwa ◽  
Hendrik G. Visser ◽  
Pieter J. Swarts ◽  
Jannie C. Swarts ◽  
...  
Keyword(s):  
Band Gap ◽  

2015 ◽  
Vol 127 (4) ◽  
pp. 1286-1288 ◽  
Author(s):  
K.O. Čajko ◽  
S.R. Lukić-Petrović ◽  
D.D. Štrbac

2005 ◽  
Vol 5 (10) ◽  
pp. 1825-1829 ◽  
Author(s):  
Elias Saion ◽  
Susilawati . ◽  
A. Doyan . ◽  
S. Zainal Abidin . ◽  
Z. Azmi . ◽  
...  

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2320 ◽  
Author(s):  
Ahang M. Hussein ◽  
Elham M. A. Dannoun ◽  
Shujahadeen B. Aziz ◽  
Mohamad A. Brza ◽  
Rebar T. Abdulwahid ◽  
...  

In the current study, the film fabrication of polystyrene (PS) based polymer nanocomposites (NCs) with tuned refractive index and absorption edge was carried out using the solution cast method. X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) light characterization techniques were performed. The structural and optical properties of the prepared films were specified. The hump of PS decreased significantly when SnTiO3 nanoparticles (NPs) were introduced. Sharp and high intense peaks of SnTiO3 NPs at a high filler ratio were observed. The crystalline size was determined for SnTiO3 NPs from the sharp crystalline peaks using Debye-Scherrer’s equation and was found to be 25.179 nm, which is close enough to that described by the supplier. Several optical parameters, such as absorption coefficient (α), refractive index (n), and optical dielectric properties, were investigated. The absorption spectra were tuned with increasing SnTiO3NPs. Upon the addition of the NPs to the PS host polymer, the absorption edge undergoes shifting to lesser photon energy sides. The optical dielectric constant (ε′) was correlated to the refractive index. The study of the optical band gap was conducted in detail using both Tauc’s model and the optical dielectric loss (ε″) parameter. The results showed that the ε″ parameter is noteworthy to be measured in the optical band gap study of materials.


2015 ◽  
Vol 5 (2) ◽  
pp. 146-154 ◽  
Author(s):  
George Varughese ◽  
P. Jithin ◽  
K. Usha

2007 ◽  
Vol 254 (1) ◽  
pp. 412-415 ◽  
Author(s):  
L. Escobar-Alarcón ◽  
A. Arrieta ◽  
E. Camps ◽  
S. Muhl ◽  
S. Rodil ◽  
...  

2021 ◽  
Author(s):  
N. S. Anad ◽  
Zakaria M Abd El-Fattah ◽  
M. Attallah ◽  
Hanaa M. Ahmed ◽  
Mohammed M. El-Okr ◽  
...  

Abstract Pristine and chromium-doped ZnO nanowires were prepared following the traditional co-precipitation method. X-ray diffraction data identified a pure wurtzite hexagonal crystal structure characteristic for ZnO, irrespective of the doping level. The particle size, as deduced form Williamson–Hall plots, was found to be 45-55 nm for all samples. Scanning electron microscopy revealed a clear nanowires morphology for the pure and doped samples, while elemental analysis ensured the successful Cr-doping. Distinct spectroscopic signatures of Cr-doping were revealed from a detailed deconvolution process applied to optical spectra of doped samples, where Cr 3+ optical transitions were unambiguously identified at ~420 and ~665 nm. Particularly relevant, is the spectral decomposition here performed for the superimposed absorption edge (~385 nm) and Cr 3+ optical resonance at ~420 nm, allowing to claim practically doping-independent optical band gap behavior in the present doping regime. This is further supported by identifying the characteristic ZnO near edge photoluminescence peak (~ 392 nm) which maintains fixed wavelength after Cr-doping. These findings contrast earlier studies on Cr-doped semiconductor nanoparticles and glass systems where the optical band gap has been largely underestimated. We attribute the inconsistence band gap values reported in literature for Cr-doped semiconductors to the proximity of Cr optical transitions to the semiconductor absorption edge.


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