Papers by Keyword: Optoelectronic

Abstract: The DFT calculations were performed to study the structural, electronic and optical properties of Si. The open source computer code, Quantum ESPRESSO used is for first-principles electronic structure modeling based on density functional theory. The optimized crystal lattice constant, band gap, density of states (DOS) and band structure were calculated. The calculated value of lattice constant was in good agreement with reported value. The band gap was calculated using three different pseudo potentials. The HSE hybrid functional provided best agreement of band gap calculations with literature values. The pseudo-dielectric functions was also calculated to estimate the optical properties including refractive indices, extinction coefficients, reflectivities and absorption coefficients in the spectral energy ranges from 0 eV to 10 eV.

Abstract: The dye-doped polymer is commonly used in the field of optoelectronics, given its effectiveness in optimising the device’s performance. This study is devoted to the synthesis and characterisation of Anchusa-Italica-doped Pentacene thin-film. Scanning electronic microscopy structural analysis, Fourier transform spectroscopy, and UV-visible transmittance spectra with a range of 300-900 nm were also carried out. The fundamental optical properties such as the absorption coefficient, optical energy gap, absorption and refractive indices were calculated based on the methods already used in the literature as Tauc’s relationship. The morphology of the samples indicated that dye structure was affected in the doped pentacene. The Fourier transform infrared technique (FT-IR) resulting spectrum of the doped samples also showed a significant absorption peak corresponding to C-H as an index of impurities. The calculated band-gap energy of the impurity sample was reduced and was the lowest compared to both the pure dye and polymer samples. The optical absorption and transmittance spectra revealed that it was positioned in the desirable ranges for optoelectronic applications. An anomaly in the absorption index was also observed through excitation of the resonance mode with transparent indication. This effect was deduced from the calculation of the refractive index. The results presented in this paper significantly contribute to the developments in the field of optoelectronic devices based on dye/polymer organic materials.

Abstract: Aluminium (Al) doped Zinc oxide (ZnO) thin films of different thicknesses were prepared on glass substrates by sol-gel spin coating method. The effect of thicknesses on micro-structural and optical properties was investigated for transparent conducting oxide (TCO) application in solar cells and other optoelectronic applications. Grazing incidence x-ray diffraction (GIXRD) showed maximum orientation along (002) plane of c-axis. The variation of different structural parameters like crystallite size, micro-strain, c-axis strain, dislocation density as a function of film thickness was investigated. The FTIR spectra confirmed the formation of Al-doped ZnO film. FESEM images showed spherical shaped nanosized grains and formation of micro pores. The optical absorption increased and absorption peak shifted towards longer wavelength (red shift) with increase in the thickness of the film respectively. The optical transmittance of all the films has a transparency of more than 75% in the visible region. The optical band gap (E_g) decreased with increase in the film thickness. The diffused reflectance (DRS) showed very low reflectance in the region of 400-800 nm, but increased in the 800-900 nm region. Photoluminescence (PL) spectra of the prepared films showed intense band edge UV and low intense visible emissions respectively. The effect of thickness of Al-doped ZnO film on micro-structure, surface morphology, optical absorption and transmittance, diffused reflectance and PL have been investigated and the results are reported.

Abstract: With the continuous development of football games, more and more football matches are hold in the world. From the World Cup to the big league, the erroneous decisions of the goals by referee always became the focus of the games. Federation International de Football Association (FIFA) is discussing now to introduce high technology to the football games to assist the judgment of the referee. In this paper, an advanced detection technology for soccer goal is proposed. This goal detection technology is based on the optical principle, high speed camera, as long as infrared detection devices. By detecting the change of electronic signal in the moment of goal, which can cut off the laser beam, the goal can be detected. In addition, the detection results and in-situ video are transmitted in real time to the arbitrators, which can reduce the goal disputes and make the game of football more fair.

Abstract: In this research, optoelectronic devices consisted of an infrared light emitting diode and a phototransistor with no special handling or third party-packaging were irradiated to ionizing radiation utilizing x-rays. It was found that the devices under test (DUTs) undergo performance degradation in their functional parameters during exposure to x-rays. These damaging effects are depending on their current drives and also the Total Ionizing Dose (TID) absorbed. The TID effects by x-rays are cumulative and gradually take place throughout the lifecycle of the devices exposed to radiation.

Abstract: This study investigates the effects of damp heat stability on the optoelectronic properties of ZnO:Al (AZO) and ZnO:Ga(GZO) films with respect to thin-film solar cells. The lowest resistivities of AZO and GZO thin films are 8.2621×10-4 Ω-cm and 2.8561×10-4 Ω-cm, respectively. After damp heat testing for 999h, the resistivities of AZO and GZO thin film increase by 39.72% and 11.97%, respectively. XPS binding energy analysis shows that the AZO thin film has a higher O 1s spectrum than the GZO thin film. Thus, the carrier concentration of films decreases, as a higher binding energy is attributed to the chemisorbed oxygen atoms (O-). Experimental results show that after expousre to a damp heat test at 85°C and 85% relative humidity for electrical, optical, structural, and morphological analysis, GZO films are more stable than AZO films.

Abstract: Heterostructure device concepts promise several advantages in micro- and optoelectronics. From the material point of view, the main obstacle to be overcome is the large lattice mismatch of silicon based heterostructures. One of the best of them, silicon germanium (SiGe) is lattice mismatched to silicon by up to 4% depending on its Ge content. Basic investigations on strained layer growth, interface properties, and deviation from equilibrium are done with SiGe / Si heterostructures. Early results are discussed in context with our recent understanding. The application focus of this review is devoted to micro- and optoelectronic devices which could be fabricated after solving or understanding the basic interface problems. This includes devices already in production, and those in emerging fields for inclusion in the next generation of integrated circuits, as well as a selection of future device concepts with high merits to be proven in experiment.

Abstract: In the present study the distribution of nanofillers in the polyurethane matrix and the composite properties were investigated. As a nanofiller, zirconium oxide doped with 10% Eu3+ was used. The nanofiller was added at 0.1 wt%. Different ways of nanofiller incorporation were investigated. The microstructure of the obtained materials was examined by atomic force microscopy in force modulation. The size analysis of the nanofiller was investigated with HRSEM. The thermal (DSC, TGA) properties of polyurethane nanocomposites were also investigated in addition to the analysis of transmittance and luminescence of obtained materials. The results obtained indicate a possibility of fabrication of polymeric nanocomposites for optoelectronic applications via a relatively inexpensive processing route.

Abstract: This paper presents the results of studies on ZrO2 containing 10% Eu3+ as a nanofiller in polyurethane nanocomposites with luminescent properties. The nanocomposites, which are potential materials for electro-optical-electronic applications, were prepared by in-situ polymerization. Emission spectra, thermodegradation, thermal analysis and mechanical properties of polyurethane ZrO2/10% Eu3+ were investigated and the structure examined using HRSEM. The aim was to investigate the influence of the distribution of nanofillers in the composite and the structure of hard domains of polyurethanes on the relevant properties for opto-electronic applications.

Abstract: The paper presents the results of research into the dielectric characteristics of modified Kapton and Upilex polyimides with C60 – fullerene contents of 0.1-2.0 % wt. The influence of temperature and frequency on the time constants of b-relaxation of modified polyimides is shown.