Possible Sequence of Hole Injection in YBa2Cu3O6+y and Reverse Model of Metallization for La2CuO4/Nd2CuO4 by Impurity Hole/Electron Levels in the Band Gap

Author(s):  
H. Tolentino ◽  
A. Fontaine ◽  
A. M. Flank ◽  
P. Lagarde ◽  
J.-Y. Henry ◽  
...  
Keyword(s):  
Band Gap ◽  
2020 ◽  
Vol 32 (19) ◽  
pp. 8158-8168
Author(s):  
Linda Nhon ◽  
Aaron D. Taggart ◽  
Taylor Moot ◽  
M. Kyle Brennaman ◽  
Pradeepkumar Jagadesan ◽  
...  

Author(s):  
B Chettri ◽  
P. K. Patra ◽  
Lalmuan Chhana ◽  
Lalhriat Zuala ◽  
Swati Verma ◽  
...  

We have reported the electronic, magnetic, and optical properties of the top layer carbon-doped hexagonal Boron Nitride(h-BN) bilayer at B/N-sites using the density functional theory implemented in Quantumwise VNL-ATK package. The calculated structural and electronic properties of the h-BN bilayer are in agreement with the previously reported results. A single carbon doping on B and N sites modifies the large band gap semiconducting behaviour of h-BN bilayer similar to dilute magnetic semi-conducting material with a net magnetic moment of 1.001 μ B and 0.998 μ B , respectively. For double doping at B/N sites net magnetic moment increases to 1.998 μ B and 1.824 μ B , respectively. Whereas for triply carbon doped bilayer system at B/N sites, the system changes to metallic behaviour. Upon carbon doping at N-site, we obtained transition from Non-Magnetic semiconductor(Pristine) → Magnetic semiconductor(1C) → Half-Metal ferromagnetic(2C) → Metal(3C). Whereas, in case of doping at the B-site, we observed transition from Non-Magnetic Semiconductor(Pristine) → Magnetic Semiconductor(1C) → Metal (2C, 3C). Analysis from the PDOS plot of the car- bon doped systems reveals that the net magnetic moments are contributed by the 2p orbitals of carbon and partial contribution from the neighboring nitrogen and boron atoms, respectively. As 1,2C doping at the B-site reduces the energy band gap to 0.81-1.8 eV which falls in the visible spectrum and thus such system further opens up an opportunity to be utilised as a photocatalys material. Our carbon doped systems show a magnetic semiconducting behavior with a nite magnetic moment which is one of the criteria for a spintronic material. So, our system looks promising in this regard. Also, Carbon doping can be considered as a simple approach to tune the band gap of the Boron Nitride bilayer system.


Author(s):  
Joanna L. Batstone

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.


Author(s):  
J.M. Bonar ◽  
R. Hull ◽  
R. Malik ◽  
R. Ryan ◽  
J.F. Walker

In this study we have examined a series of strained heteropeitaxial GaAs/InGaAs/GaAs and InGaAs/GaAs structures, both on (001) GaAs substrates. These heterostructures are potentially very interesting from a device standpoint because of improved band gap properties (InAs has a much smaller band gap than GaAs so there is a large band offset at the InGaAs/GaAs interface), and because of the much higher mobility of InAs. However, there is a 7.2% lattice mismatch between InAs and GaAs, so an InxGa1-xAs layer in a GaAs structure with even relatively low x will have a large amount of strain, and misfit dislocations are expected to form above some critical thickness. We attempt here to correlate the effect of misfit dislocations on the electronic properties of this material.The samples we examined consisted of 200Å InxGa1-xAs layered in a hetero-junction bipolar transistor (HBT) structure (InxGa1-xAs on top of a (001) GaAs buffer, followed by more GaAs, then a layer of AlGaAs and a GaAs cap), and a series consisting of a 200Å layer of InxGa1-xAs on a (001) GaAs substrate.


2020 ◽  
Vol 91 (3) ◽  
pp. 30201
Author(s):  
Hang Yu ◽  
Jianlin Zhou ◽  
Yuanyuan Hao ◽  
Yao Ni

Organic thin film transistors (OTFTs) based on dioctylbenzothienobenzothiophene (C8BTBT) and copper (Cu) electrodes were fabricated. For improving the electrical performance of the original devices, the different modifications were attempted to insert in three different positions including semiconductor/electrode interface, semiconductor bulk inside and semiconductor/insulator interface. In detail, 4,4′,4′′-tris[3-methylpheny(phenyl)amino] triphenylamine (m-MTDATA) was applied between C8BTBTand Cu electrodes as hole injection layer (HIL). Moreover, the fluorinated copper phthalo-cyanine (F16CuPc) was inserted in C8BTBT/SiO2 interface to form F16CuPc/C8BTBT heterojunction or C8BTBT bulk to form C8BTBT/F16CuPc/C8BTBT sandwich configuration. Our experiment shows that, the sandwich structured OTFTs have a significant performance enhancement when appropriate thickness modification is chosen, comparing with original C8BTBT devices. Then, even the low work function metal Cu was applied, a normal p-type operate-mode C8BTBT-OTFT with mobility as high as 2.56 cm2/Vs has been fabricated.


2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.


1981 ◽  
Vol 42 (C4) ◽  
pp. C4-59-C4-62
Author(s):  
H. Leschke ◽  
B. Kramer
Keyword(s):  
Band Gap ◽  

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-1025-C4-1028 ◽  
Author(s):  
R. Carius ◽  
R. Fischer ◽  
E. Holzenkämpfer
Keyword(s):  

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