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

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.

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

2006 ◽  
Vol 21 (3) ◽  
pp. 623-631 ◽  
Author(s):  
S. Tripathi ◽  
R. Brajpuriya ◽  
C. Mukharjee ◽  
S.M. Chaudhari
Keyword(s):  
Thin Film ◽  
Particle Size ◽  
Band Gap ◽  
Quantum Confinement ◽  
Near Infrared ◽  
Quantum Confinement Effect ◽  
Multilayer Structures ◽  
Absorption Measurements ◽  
Gap Values

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.

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

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

scholarly journals Augmented band gap tunability in indium-doped zinc sulfide nanocrystals

Nanoscale ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 3154-3163 ◽  
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.

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

MRS Advances ◽  
2016 ◽  
Vol 1 (22) ◽  
pp. 1613-1618 ◽  
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.

scholarly journals Excitonic quantum confinement modified optical conductivity of monolayer and few-layered MoS2

2016 ◽  
Vol 4 (37) ◽  
pp. 8822-8828 ◽  
Author(s):  
Guang Yi Jia ◽  
Yue Liu ◽  
Jing Yu Gong ◽  
Dang Yuan Lei ◽  
Dan Li Wang ◽  
...  
Keyword(s):  
Optical Conductivity ◽  
Quantum Confinement ◽  
Theoretical Calculations ◽  
Quantum Confinement Effect ◽  
Confinement Effect ◽  
Layered Mos2

Theoretical calculations reveal that the excitonic quantum confinement effect significantly modifies the optical conductivities of monolayer and few-layered MoS2.

Deep Levels in Superlattices

1989 ◽  
Vol 163 ◽  
Author(s):  
John D. Dow ◽  
Shang Yuan Ren ◽  
Jun Shen ◽  
Min-Hsiung Tsai
Keyword(s):  
Band Gap ◽  
Quantum Confinement ◽  
Deep Level ◽  
Energy Levels ◽  
Deep Trap ◽  
Shallow Donor ◽  
Deep Levels ◽  
Band Gap Engineering ◽  
Substitutional Impurities ◽  
Superlattice Period

AbstractThe physics of deep levels in semiconductors is reviewed, with emphasis on the fact that all substitutional impurities produce deep levels - some of which may not lie within the fundamental band gap. The character of a dopant changes when one of the deep levels moves into or out of the fundamental gap in response to a perturbation such as pressure or change of host composition. For example, Si on a Ga site in GaAs is a shallow donor, but becomes a deep trap for x>0.3 in AℓxGa1-xAs. Such shallow-deep transitions can be induced in superlattices by changing the period-widths and quantum confinement. A good rule of thumb for deep levels in superlattices is that the energy levels with respect to vacuum are relatively insensitive (on a >0.1 eV scale) to superlattice period-widths, but that the band edges of the superlattices are sensitive to changes of period. Hence the deep level positions relative to the band edges are sensitive to the period-widths, and shallow-deep transitions can be induced by band-gap engineering the superlattice periods.

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

2007 ◽  
Vol 131-133 ◽  
pp. 559-562 ◽  
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.

scholarly journals Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1935 ◽  
Author(s):  
Daichi Koretomo ◽  
Shuhei Hamada ◽  
Yusaku Magari ◽  
Mamoru Furuta
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Quantum Confinement ◽  
Carrier Transport ◽  
Simulation Analysis ◽  
Quantum Confinement Effect ◽  
Energy Band Diagram ◽  
Confinement Effect ◽  
Gate Insulator ◽  
Conduction Band Offset

Electrical and carrier transport properties in In–Ga–Zn–O thin-film transistors (IGZO TFTs) with a heterojunction channel were investigated. For the heterojunction IGZO channel, a high-In composition IGZO layer (IGZO-high-In) was deposited on a typical compositions IGZO layer (IGZO-111). From the optical properties and photoelectron yield spectroscopy measurements, the heterojunction channel was expected to have the type–II energy band diagram which possesses a conduction band offset (ΔEc) of ~0.4 eV. A depth profile of background charge density indicated that a steep ΔEc is formed even in the amorphous IGZO heterojunction interface deposited by sputtering. A field effect mobility (μFE) of bottom gate structured IGZO TFTs with the heterojunction channel (hetero-IGZO TFTs) improved to ~20 cm2 V−1 s−1, although a channel/gate insulator interface was formed by an IGZO−111 (μFE = ~12 cm2 V−1 s−1). Device simulation analysis revealed that the improvement of μFE in the hetero-IGZO TFTs was originated by a quantum confinement effect for electrons at the heterojunction interface owing to a formation of steep ΔEc. Thus, we believe that heterojunction IGZO channel is an effective method to improve electrical properties of the TFTs.

Electronic and Transmission Properties of Low Buckled GaAs Armchair Nanoribbons

2017 ◽  
Vol 33 (3-4) ◽  
pp. 91 ◽  
Author(s):  
B. P. Pandey
Keyword(s):  
Band Gap ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Thermal Conductance ◽  
First Principle ◽  
Great Flexibility ◽  
Direct Band Gap ◽  
Transmission Properties ◽  
Direct Band ◽  
Principle Theory

The electronic and transmission properties of N atom width (N: 4, 8, 12, 16)low-buckled (LB) armchair GaAs hydrogen (H) passivated nanoribbons (NA GaAs NRs) are studied with the help of first-principle theory. In low buckled armchair GaAs nanoribbon, quantum confinement effect is observed due to which all of the investigated NA GaAs NRs with H passivated are found to be semiconducting. The fundamental direct band gap at k-point Г (gamma) have been calculated, which exhibit interesting width dependent (N: 4~16) behaviour of bandgap. The H passivated edge of NA GaAs NRs with different width of nanoribbons provides great flexibility to modulate fundamental bandgap. The transmission coefficient is calculated from which thermal conductance has been calculated forall width of GaAs armchair nanoribbon.

Sign in / Sign up

Export Citation Format

Share Document