Journal of Optoelectronical Nanostructures
Volume:5 Issue: 2, Spring 2020

In this paper, a novel tunnel field effect transistor (TFET) is introduced, thatdue to its superior gate controllability, can be considered as a promising candidate forthe conventional TFET. The proposed electrically doped heterojunction TFET(EDHJTFET) has a 3D core-shell nanotube structure with external and internal gatessurrounding the channel that employs electrostatically doping rather than ionimplantationfor creating the tunneling junction. The staggered type InAs/GaAs0.1Sb0.9heterojunction devices, considerably amplifies the band to band tunneling rate. Theeffect of device geometry and physical design parameters on the performance of thedevice are comprehensively investigated and cut off frequency of 200GHz, on/offcurrent ratio of 9.41×108 and subthreshold swing of 8.7 mV/dec are achieved. Thesensitivity analysis reveals that core/shell control gate workfunction and doping densityare critical design parameters that may affect the device performance. Moreover, theinsensitivity of off-state current to the drain voltage variation and channel length scalingsignifies the application of this device in nanoscale regime.

Tetragonal zirconia (t-ZrO2) nanoparticles were synthesized from thezirconium chloride using the co-precipitation technique and characterized by variousmeasurement techniques. FESEM analysis further revealed spherical shaped NPs andHR-TEM analysis determined the size of the particles in the range of 14.5 nm. The bandgap energy was estimated 4.0 eV. The UV (350 nm) emission was observed from PLspectrum. The photocatalytic degradation of the as-prepared ZrO2 nanoparticles werestudied under UV light irradiation using ciprofloxacin (CIP) as a model organicpollutant. Results showed that 50% degradation were achieved within 15 min.

In this paper, we present an analytical model to analysis the kirk effect onstatic and dynamic responses of quantum well heterojunction bipolar transistor lasers(HBTLs). Our analysis is based on solving the kirk current equation, continuityequation and rate equations of HBTL. We compare the performance (current gain,output photon number and small signal modulation bandwidth) of the transistor laserwith different levels of the kirk current. We show that, at high collector currents, thestatic and small signal behavior of HBTL depend on kirk current level. The resultsindicate that, the level of kirk current affect current gain, output photon number andmodulation bandwidth From simulation results, it can befound that, kirk effect hasdestructive influence on HBTL performance. It was found that lower modulationbandwidth and lower current gain occurs at lower kirk current level. For increasing kirkcurrent, the high collector-base voltage and high collector length was proposed.

Zirconium oxide has found extensive applications in various industries becauseof its excellent properties such as high strength; high-temperature resistance;extraordinary wearing resistance; ionic conductivity; and corrosion resistance. Also, someProperties like high melting point, high mechanical and thermal strength, high dielectricconstant and low conductivity have introduced this material as a prominent candidate forengineering applications. In this study, zirconium oxide (ZrO2) Nano fibers wassynthesized by calcination of propoxide zirconium oxide/polyvinyl alcohol using sol-geland electrospinning methods. The morphology of the Nano fibers was verified byscanning electron microscopy (SEM) and its crystalline phase was investigated by x-raydiffraction and energy-dispersive x-ray spectroscopy (EDS). The mean diameter of theNano fibers varied in the range of 70-200 nm. XRD patterns also indicated the presenceof monoclinic and tetragonal phases in the Nano fibers calcined at 700 ℃. Results alsorevealed that this new precursor can be used in the electrospinning technique to obtainZrO2 Nano fibers with relatively high purity.

In this study, using density functional theory and the SIESTA computationalcode, we investigate the electronic and optical properties of the armchair graphenenanoribbons and the armchair boron nitride nanoribbons of width 25 in the presence of atransverse external electric field. We have observed that in the absence of the electricfield, these structures are semiconductors with a direct energy band at Γ point andapplying electric field on them causes to change in the band structure, increasing theband gap and even eliminating the band gap. Increasing the intensity of the applyingfield on the graphene nanoribbons reduces the distance between the maximum of thehighest valence band and the minimum of the lowest conduction band and shifts theconvergence of these two bands in K space from the Γ point to the X point. The energyband gap of the boron nitride nanoribbons also has been decreased from 4.46 eV to lessthan 32.6 meV in presence of a transverse electric field of intensity about 0.30 V/Angand a semiconductor-metal transition was observed in the presence of the strongerfields.Next, we investigate the effect of the transverse electric field on the optical propertiesof both nanoribbons. Of course, in order to study the optical behavior of these systems,we apply only a radiation with the parallel polarization. According to the changes thatthe electric field makes on the band structure, we observed changes in the location andintensity of the optical graphs peaks. Also with increasing the intensity of the field, weobserve a significant increase in the static dielectric constant and the plasmonicbehavior of these structures.

Perovskite solar cells have become an attractive subject in the solar energydevice area. During ten years of development, the energy conversion efficiency has beenimproved from 2.2% to more than 22%, and it still has a very good potential for furtherenhancement. In this paper, a numerical model of the perovskite solar cell with thestructure of glass/ FTO/ TiO2/ H3NH3PbI3/ HTM/Au by using Silvaco Atlas software ispresented. The effect of hole transport material characteristics, including hole mobilityand band gap offset of organic and inorganic HTM layers such as Spiro-MOeTAD, CuOand Cu2O on the performance of PSCs are investigated. The simulation results reveal thatwith increase of hole mobility in hole transport layer, the cell efficiency is increases.Meanwhile, the solar cell exhibits a better performance by using inorganic materials likeCuO and Cu2O as hole transport layer, than by using Spiro-MOeTAD, particularly theefficiency reaches 22.12% when Cu2O is used.

In this study, we were investigated behavior the electrochemical reductionof nitrite at a hemoglobin (Hb) immobilized on glass carbon electrode (GCE) containingpolypyrol nanofiber (ppy) films. Polypyrrole (PPy) nanofibers have been constructed onGCE applying electrochemical technique, and can to deposit diverse polymers onminiaturized electrodes with this common method. The structure of the acquiredelectrode and the electrochemical behavior were characterized using Scanning ElectronMicroscopy (SEM), Cyclic Voltammetry (CV), and Linear Sweep Voltammetry (LSV).The immobilized Hb showed an irreversible reduction peak with a formal potential of –0.72 versus Ag/AgCl, in 0.1M pH 4.5 acetate buffer. The immobilized Hb exhibitedremarkable electrocatalytic activity for the reduction of nitrite. Under the optimalcondition the nitrite concentrations range 2.0×10−4 to 46.0×10−4 M with a detection limitof 6.2×10−5 M (at S/N=3). The resulting biosensor has been successfully applied to thedetermination of nitrite in water samples. The produced modified electrode for nitritedetermination has been explored within the presence of the interfering substancesincluding a number of common ions and cations, demonstrating great selectivity.