Determination of band gap in polycrystalline Si/Ge thin film multilayers

The valence band (VB) photoemission supported by ultraviolet–visible–near infrared spectroscopy techniques were used to determine the band gap values of polycrystalline Si and Ge single layers as well as of Si/Ge multilayer structures. The band gap values obtained from VB photoemission measurements for these structures were found to be much larger than their corresponding bulks and to match well with those determined from standard optical absorption measurements. In each case, the VB offset values were obtained by considering the corresponding VB maximum as a reference. The increase in band gap in case of thin single layers of Si and Ge with respect to bulks were interpreted in terms of quantum confinement effect, while in case of multilayer sample, the effect of various factors such as (i) intermixing leading to the formation of SiGe alloy, (ii) roughness at the interface, (iii) particle size, and (iv) strain seem to play an important role in the observed change in band gap.

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Self-sacrifice Te template synthesis of new phase PbmSb2nTem+3n nanorods via Pb2+/Sb3+ synergistic effect

RSC Advances ◽

10.1039/c5ra22381d ◽

2015 ◽

Vol 5 (127) ◽

pp. 105379-105392 ◽

Cited By ~ 3

Author(s):

Ziming Su ◽

Qun Wang ◽

Jianhuan Li ◽

Guangjun Zhang

Keyword(s):

Synergistic Effect ◽

Band Gap ◽

Template Synthesis ◽

Quantum Confinement ◽

Quantum Confinement Effect ◽

Confinement Effect ◽

New Phase ◽

Topotactic Transformation ◽

Gap Values

New phase PbmSb2nTem+3n nanorods were synthesized using Te self-sacrifice template via Pb2+/Sb3+ synergistic effect topotactic transformation, which showed bigger band gap values due to the quantum confinement effect.

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Effects of Quantum Confinements in Tin Sulphide Nanocrystals Produced by Wet-Solution Technique

Asia Pacific Journal of Energy and Environment ◽

10.18034/apjee.v6i1.261 ◽

2019 ◽

Vol 6 (1) ◽

pp. 37-42

Author(s):

Cliff Orori Mosiori

Keyword(s):

Thin Film ◽

Band Gap ◽

Quantum Confinement ◽

Theoretical Calculations ◽

Quantum Confinement Effect ◽

Energy Levels ◽

Particle Energy ◽

Ion Source ◽

Solution Technique ◽

Tin Chloride

In thin film nano-crystals studies, electron energy levels are known not continuous in the bulk thin films but are rather discrete(finite density of states) because of confinement of their electron wave functions to the physically dimensions of the particles. This phenomenon is called Quantum confinement and therefore nano-crystals are also referred to Quantum dots. The quantum confinement effect is mainly observed when the size of the particle involved is too small to be comparable to the wavelength of the electron. To understand this effect, this study broke the words confinement to mean to confine the motion of randomly moving electron to restrict its motion in specific energy levels (discreteness) and the term quantum to reflect the atomic realm of particles involved in this study. So as the size of a particle decrease to a nano scale, then the decrease in confining dimension causes the particle energy levels to be too discrete and at the same time widens up the band gap. As a result the ultimately effect is that the band gap energy increases. In this study, nanocrystalline tin sulphide (SnS) powder was prepared using tin chloride (SnCl2) as a tin ion (Sn+2) source and sodium sulfide (Na2S) as a sulfur (S-2) ion source using solution magneto DC sputtering technique. The as-synthesized thin film in form of nanoparticles were then qualitatively and quantitatively analyzed and characterized in terms of their morphological, structural and optical properties and found to have an orthorhombic structure whose direct band gap had blue shifted (1.74 eV) and was confirmed using theoretical calculations of exciton energy based on the potential morphing method (PMM) in the Hartree Fock approximation.

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Tunable Quantum Confinement Effect on Non-volatile Thin Film Polymer Memory Device

10.1557/proc-1134-bb05-04 ◽

2008 ◽

Author(s):

Augustin J. Hong ◽

Kang L. Wang ◽

Wei Lek Kwan ◽

Yang Yang ◽

Dayanara Parra ◽

...

Keyword(s):

Thin Film ◽

Quantum Confinement ◽

Quantum Confinement Effect ◽

Memory Device ◽

Confinement Effect ◽

Film Polymer ◽

Polymer Memory

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Augmented band gap tunability in indium-doped zinc sulfide nanocrystals

Nanoscale ◽

10.1039/c8nr08830f ◽

2019 ◽

Vol 11 (7) ◽

pp. 3154-3163 ◽

Cited By ~ 5

Author(s):

Enrico Della Gaspera ◽

Joseph Griggs ◽

Taimur Ahmed ◽

Sumeet Walia ◽

Edwin L. H. Mayes ◽

...

Keyword(s):

Band Gap ◽

Zinc Sulfide ◽

Quantum Confinement ◽

Quantum Confinement Effect ◽

Confinement Effect ◽

Indium Doping ◽

Zns Nanocrystals ◽

Sulfide Nanocrystals

Indium doping in ZnS nanocrystals heavily affects the band gap beyond quantum confinement effect with unprecedented tunability in the UVA/UVB range.

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Density Functional Theory Study on Energy Band Gap of Armchair Silicene Nanoribbons with Periodic Nanoholes

MRS Advances ◽

10.1557/adv.2016.123 ◽

2016 ◽

Vol 1 (22) ◽

pp. 1613-1618 ◽

Cited By ~ 4

Author(s):

Sadegh Mehdi Aghaei ◽

Irene Calizo

Keyword(s):

Density Functional Theory ◽

Band Gap ◽

Energy Band ◽

Quantum Confinement ◽

Density Functional ◽

Quantum Confinement Effect ◽

Density Functional Theory Study ◽

Energy Band Gap ◽

Functional Theory ◽

Silicene Nanoribbons

ABSTRACTIn this study, density functional theory (DFT) is employed to investigate the electronic properties of armchair silicene nanoribbons perforated with periodic nanoholes (ASiNRPNHs). The dangling bonds of armchair silicene nanoribbons (ASiNR) are passivated by mono- (:H) or di-hydrogen (:2H) atoms. Our results show that the ASiNRs can be categorized into three groups based on their width: W = 3P − 1, 3P, and 3P + 1, P is an integer. The band gap value order changes from “EG (3P − 1) < EG (3P) < EG (3P + 1)” to “EG (3P + 1) < EG (3P − 1) < EG (3P)” when edge hydrogenation varies from mono- to di-hydrogenated. The energy band gap values for ASiNRPNHs depend on the nanoribbons width and the repeat periodicity of the nanoholes. The band gap value of ASiNRPNHs is larger than that of pristine ASiNRs when repeat periodicity is even, while it is smaller than that of pristine ASiNRs when repeat periodicity is odd. In general, the value of energy band gap for ASiNRPNHs:2H is larger than that of ASiNRPNHs:H. So a band gap as large as 0.92 eV is achievable with ASiNRPNHs of width 12 and repeat periodicity of 2. Furthermore, creating periodic nanoholes near the edge of the nanoribbons cause a larger band gap due to a strong quantum confinement effect.

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Determination of the Quantum Dot Band Gap Dependence on Particle Size from Optical Absorbance and Transmission Electron Microscopy Measurements

ACS Nano ◽

10.1021/nn303130d ◽

2012 ◽

Vol 6 (10) ◽

pp. 9021-9032 ◽

Cited By ~ 88

Author(s):

Doris Segets ◽

J. Matthew Lucas ◽

Robin N. Klupp Taylor ◽

Marcus Scheele ◽

Haimei Zheng ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Particle Size ◽

Quantum Dot ◽

Band Gap ◽

Optical Absorbance ◽

Transmission Electron

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Properties of Nanostructure Formed on SiO2/Si Interface by Laser Radiation

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.131-133.559 ◽

2007 ◽

Vol 131-133 ◽

pp. 559-562 ◽

Cited By ~ 9

Author(s):

Arthur Medvid ◽

Igor Dmitruk ◽

Pavels Onufrijevs ◽

Iryna Pundyk

Keyword(s):

Optical Properties ◽

Laser Radiation ◽

Band Gap ◽

Quantum Confinement ◽

Quantum Confinement Effect ◽

Confinement Effect ◽

Visible Range ◽

Pulsed Nd:Yag Laser ◽

Self Organized ◽

Graded Band Gap

The aim of this work is to study optical properties of Si nanohills formed on the SiO2/Si interface by the pulsed Nd:YAG laser radiation. Nanohills which are self-organized on the surface of Si, are characterized by strong photoluminescence in the visible range of spectra with long wing in the red part of spectra. This peculiarity is explained by Quantum confinement effect in nanohillsnanowires with graded diameter. We have found a new method for graded band gap semiconductor formation using an elementary semiconductor. Graded change of band gap arises due to Quantum confinement effect.

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