scholarly journals Magnetotransport property of negative band gap HgCdTe bulk material

2017 ◽  
Vol 66 (24) ◽  
pp. 247301
Author(s):  
Shen Dan-Ping ◽  
Zhang Xiao-Dong ◽  
Sun Yan ◽  
Kang Ting-Ting ◽  
Dai Ning ◽  
...  
Keyword(s):  
Band Gap ◽  
Bulk Material ◽  
Magnetotransport Property ◽  
Negative Band

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.

scholarly journals Optical, Magnetic and Adsorptive Properties of Prepared Copper(II) Oxide

2020 ◽  
Vol 68 (1) ◽  
pp. 7-12
Author(s):  
Md Ataur Rahman ◽  
Tajmeri SA Islam ◽  
Md Mufazzal Hossain
Keyword(s):  
Infrared Spectroscopy ◽  
Band Gap ◽  
Surface Characterization ◽  
Bulk Material ◽  
Adsorbed Layer ◽  
Attenuated Total Reflection ◽  
Layer By Layer ◽  
X Ray ◽  
Direct Band ◽  
Visible Reflectance

We report the surface morphology, structural propertiesand surface characterization of copper(II) oxide by scanning electron microscope, energy dispersive X-ray spectroscopy, Fourier transformation infrared spectroscopy, attenuated total reflection infrared spectroscopy and X-ray diffraction. All the data of analysis were consistent with each other and bear the evidence for the purity of the prepared oxide. Kubelka-Munk (K-M) theory is used for the determination of direct band gap of the prepared oxide from UV-visible reflectance spectrum. The band gap value of the bulk material was found to be 4.15 0.05 eV from F(R) versus energy and (F(R) hv)n versus energy plots, with n=1/2 and n=2 Molar magnetic susceptibility and effective magnetic moment of the oxide are 3.393×10-4(cgs) and 0.895 BM respectively which suggest that the oxide is paramagnetic. Catalytic activity was investigated by the study of adsorption of brilliant red (BR) on the surface of prepared oxide in aqueous medium at room temperature. Adsorption isotherm shows that BR moleculesare adsorbed layer by layer on the surface of oxide. Study of the adsorption phenomenon in this work suggest that copper(II) oxide has significant adsorptive and catalytic property. Dhaka Univ. J. Sci. 68(1): 7-12, 2020 (January)

Proteome Mediated Synthesis of Biocompatible Green Fluorescence Cerium Oxide Quantum Dots with Enhanced Antioxidant Activity

2020 ◽  
Vol 12 (6) ◽  
pp. 831-839
Author(s):  
Amita A. Bhagit ◽  
Sveeta V. Mhatre ◽  
R. P. Yadav
Keyword(s):  
Quantum Dots ◽  
Antioxidant Activity ◽  
Band Gap ◽  
Cerium Oxide ◽  
Bulk Material ◽  
Degree Of Crystallinity ◽  
Light Quantum ◽  
Vis Spectroscopy

Biocompatibility of quantum dots make good candidature for in vivo and in vitro diagnostic applications. In this study biocompatible cerium oxide quantum dots (CeO2 QDs) were synthesized from proteome of Justicia adhatoda leaf using simple aqueous protocol. Synthesized cerium oxide nanoparticle possessed green colored fluorescence under UV light. Quantum yield of CeO2 QDs was found to be 31.13% and were stable for 3 month at 4 °C. The band gap was found to be 3.26 eV which was higher than the band gap of bulk material i.e., 3.19 eV. The concentration of synthesized CeO2 QDs was determined as 165.96 ppm. These quantum dots were also characterized using an UV-Vis spectroscopy, Fourier Transform Infra-red Spectroscopy (FT-IR) and Transmission Electron Microscopy (TEM) respectively. It displayed distinct absorbance peak at 380 nm under UV-Visible spectrum. TEM images showed monodispersity of 2–5 nm spherical shaped CeO2 QDs and higher degree of crystallinity was observed by the pattern of selected area electron diffraction. In FTIR, the stretching observed at 621.65 cm–1 is assigned to Ce-O which confirmed the CeO2QDs formation. In view of biocompability, synthesized CeO2QDs were also characterised in reference to cell toxicity. Generated CeO2QDs has not showed any toxicity to J774A.1, Raw 264.7 and 3T3 cell lines in vitro cell viability assay. Significant enhancement in antioxidant activity of synthesized cerium oxide nanoparticles was observed from bulk material. This process offers plenty of advantages such as simple protocol, mild environment operation, potential for large scale commercial production of biocompatible CeO2QD. These QDs might find potential applications in both in vitro and in vivo diagnostics.

scholarly journals Laser Assisted Flow Deposition: a New Method to Grow ZnO

2012 ◽  
Vol 18 (S5) ◽  
pp. 87-88 ◽  
Author(s):  
J. Rodrigues ◽  
M. R. N. Soares ◽  
A. J. S. Fernandes ◽  
T. Monteiro ◽  
F. M. Costa
Keyword(s):  
Zinc Oxide ◽  
Band Gap ◽  
Bulk Material ◽  
Wide Band ◽  
Modern Technology ◽  
New Method ◽  
Wide Band Gap ◽  
Fundamental Science ◽  
Technology Applications

Zinc oxide (ZnO) has been one of the most studied materials in the last decades. Either as bulk material, epilayers or nanostructures, this direct wide band gap semiconductor is known to possess great potential for fundamental science and modern technology applications.

Negative-Band-Gap Quantum Dots

2011 ◽  
Author(s):  
Natalia Malkova ◽  
Garnett W. Bryant ◽  
Giti A. Khodaparast ◽  
Michael B. Santos ◽  
Christopher J. Stanton
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Negative Band

Phenomenological Modeling of Confined Phonon States in TMD Quantum Dots

MRS Advances ◽  
2018 ◽  
Vol 3 (6-7) ◽  
pp. 339-344 ◽  
Author(s):  
Lu Fang ◽  
Tamia Willliam ◽  
Kofi W. Adu ◽  
Mauricio Terrones
Keyword(s):  
Quantum Dots ◽  
Size Effect ◽  
Band Gap ◽  
Bulk Material ◽  
Single Layer ◽  
Interlayer Coupling ◽  
Quantum Size Effect ◽  
Quantum Size ◽  
Indirect Band Gap ◽  
Band Gap Tuning

ABSTRACTSeveral reports have shown band-gap tuning in TMDs, from indirect band gap in the bulk material to a direct gap in single layer due to the absence of interlayer coupling. This unique property stems from the modified electronic states. The phononic properties are extremely modified as well, due to layered effect and quantum size effect. There are several reports on layered effect; however, reports on the confined phonon states in these structures are limited. Thus, we present a preliminary studies of the confined phonon states in TMDs (WS2 and MoS2) quantum dots, and elucidate on the evolution of the phonon lineshape with diameter using a phenomenological model with an envelop function that truncates the phonon wave at the surface of the quantum dot. Furthermore, we delineate the layered effect from the quantum size effect in the phonon lineshape of WS2 and MoS2.

scholarly journals The optical properties of a- (GeS2)100-xGax thin films

2019 ◽  
Vol 11 (21) ◽  
pp. 28-36
Author(s):  
Bushra A. Hasan
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Constants ◽  
Optical Band Gap ◽  
Bulk Material ◽  
Localized States ◽  
Optical Parameters ◽  
Evaporation Technique ◽  
Opposite Manner ◽  
Average Bond

Thin films whose compositions can be expressed by (GeS2)100-xGax (x=0, 6,12,18) formula were obtained by thermal evaporation technique  of bulk material at a base pressure of ~10-5 torr. Optical transmission spectra of the films were taken in the range of 300-1100 nm then the optical band gap, tail width of localized states,  refractive index, extinction coefficient were calculated. The optical constants were found to increase at low concentration of Ga (0 to12%) while they decreases with further addition of Ga. The optical band gap was found to change in opposite manner to that of optical constants. The variation in the optical parameters are explained in terms of average bond energy of the system.

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