Electrical Properties Of Semiconductors Research Articles

Thermoelectric Performance of Ca2Si Synthesized by High-Temperature Melting

Ca2Si was successfully synthesized via a high-temperature melting furnace and a spark plasma sintering process, allowing its thermoelectric properties to be studied. High-temperature melting furnaces were utilized to inhibit the volatilization of Ca elements during the preparation stage, ensuring the production of high-purity Ca2Si. The resistivity of Ca2Si increased gradually with rising temperature and reached 12 mΩ·cm at 873 K, demonstrating semi-metallic characteristics. In the temperature range of 323 K–873 K, Ca2Si displayed relatively low total thermal conductivity, from 1.1 to 1.7 W·m−1·K−1. Nevertheless, Ca2Si attained a maximum thermoelectric figure of merit (ZT) of 0.1 due to the atypical behavior and electrical properties of semiconductors. In contrast, Mg2Si achieved a ZT value of 0.32 at 873 K, owing to its exceptional Seebeck coefficient.

Au decorated ZnO nanostructures for enhanced visible emission and memory applications

Metal/semiconductor nanocomposites present the most versatile way to tune the optical and electrical properties of semiconductors at the nanometer scale. In the present study, Au/ZnO contacts were investigated for their potential applications in optoelectronic devices. There is general agreement that the resonant excitation of surface plasmons (SP) of metal nanoparticles (NP) can couple with the excitons of semiconductors and tune their optical emissions. In this work, the SP and exciton coupling is thoroughly examined using temperature dependent photoluminescence (PL) spectroscopy and Raman spectroscopy in the Au-NPs coated ZnO nanowires. Peculiar to the conventional optical response of Au/ZnO nanostructures at room temperature, PL measurements manifest the suppression of the band edge emissions and enhanced deep level emissions after Au-NPs coating. Raman spectroscopy showed the surface-enhanced Raman scattering (SERS) effect due to field enhancement of the incident light by the SP thus demonstrating potential in ultrasensitive sensing applications. Also, ZnO memristors were fabricated with Au electrodes that exhibited high endurance and longtime retentive bipolar resistive switching characteristics with low SET/RESET voltages. Altogether, present results demonstrate that Au/ZnO composites hold promise for plasmonic based nanoelectronics for memory and neuromorphic applications.

Optically Active Telecom Defects in MoTe2 Fewlayers at Room Temperature.

The optical and electrical properties of semiconductors are strongly affected by defect states. The defects in molybdenum ditelluride (MoTe2) show the potential for quantum light emission at optical fiber communication bands. However, the observation of defect-related light emission is still limited to cryogenic temperatures. In this work, we demonstrate the deep defect states in MoTe2 fewlayers produced via a standard van der Waal material transfer method with a heating process, which enables light emission in the telecommunication O-band. The optical measurements show evidence of localized excitons and strong interaction among defects. Furthermore, the optical emission of defects depends on the thickness of the host materials. Our findings offer a new route for tailoring the optical properties of two-dimensional materials in optoelectronic applications.

Investigation of Advanced Oxidation Process in the Presence of TiO2 Semiconductor as Photocatalyst: Property, Principle, Kinetic Analysis, and Photocatalytic Activity

Water pollution is considered a serious threat to human life. An advanced oxidation process in the presence of semiconductor photocatalysts is a popular method for the effective decomposition of organic pollutants from wastewater. TiO2 nanoparticles are widely used as photocatalysts due to their low cost, chemical stability, environmental compatibility and significant efficiency. The aim of this study is to review the photocatalytic processes and their mechanism, reaction kinetics, optical and electrical properties of semiconductors and unique characteristics of titanium as the most widely used photocatalyst; and to compare the photocatalytic activity between different titania phases (anatase, rutile, and brookite) and between colorful and white TiO2 nanoparticles. Photocatalytic processes are based on the creation of electron–hole pairs. Therefore, increasing stability and separation of charge carriers could improve the photocatalytic activity. The synthesis method has a significant effect on the intensity of photocatalytic activity. The increase in the density of surface hydroxyls as well as the significant mobility of the electron–hole pairs in the anatase phase increases its photocatalytic activity compared to other phases. Electronic and structural changes lead to the synthesis of colored titania with different photocatalytic properties. Among colored titania materials, black TiO2 showed promising photocatalytic activity due to the formation of surface defects including oxygen vacancies, increasing the interaction with the light irradiation and the lifetime of photogenerated electron–hole pairs. Among non-metal elements, nitrogen doping could be effectively used to drive visible light-activated TiO2.

Dopant compensation in p-type doped MAPb1−xCuxI3 alloyed perovskite crystals

Tuning the optical and electrical properties of semiconductors by designed doping is the basis of most energy-related semiconductor optoelectronic devices. In this Letter, we report the dopant compensation effect of P-type doped MAPb1−x CuxI3 alloyed perovskite crystals. MAPb1−xCuxI3 single crystals were prepared by the inverse temperature crystallization method using cupric chloride (CuCl2) as the doping source. By XRD, XPS, STEM, and photoluminescence (PL) spectra analyses, we demonstrate that the doped cupric (Cu2+) ions can partially substitute lead (Pb2+) ions and form Cu–Pb based crystal semiconductor alloys of MAPb1−xCuxI3 with tunable bandgap by controlling the Pb/Cu ratio. More detailed XPS analysis of the doped crystal shows that the Cu2+ ions in MAPb1−xCuxI3 are partially reduced by I− ions, and the coexistence of two valence states of Cu species (Cu2+ and Cu+) was observed in the doped crystals. Hall results of MAPb1−xCuxI3 semiconductors show that the presence of reduced Cu+ ions impels the change of conductive type from weak N-type to P-type obviously, while the resistivity of doped MAPb1−xCuxI3 increases significantly from 104 to 107 Ω cm. The defect-related optical fingerprints of cupric doped crystals were investigated in detail by temperature-dependent PL spectroscopy. The pristine MAPbI3 perovskite crystal exhibits intrinsic donor bound exciton (D0X) luminescence at low temperature (10 K), while the doped MAPb1−xCuxI3 perovskites exhibit donor-acceptor or bound exciton (A0X) peaks related to a Cu+ dopant in sequence with the increase in the Cu ion content. These results indicate that the doping of Cu2+/+ ions into the MAPb1−xCuxI3 crystal not only changes the semiconductor bandgap but also causes the dopant compensation.

Physical Layer Security: About Humans, Machines and the Transmission Channel

In an increasingly interconnected and globalized world in which the volume but also the confidentiality of transmitted content is becoming ever more important, trust, confidence and trustworthiness are of fundamental importance. Particularly in human societies, this trust is established, sustained and strengthened by personal relationships and experiences. But, in a globally connected world with Cyber-Physical Production Systems (CPPS), Industrial Internet of Things (IIoT) and Digital Twins (DTs), these personal relationships do not longer exist. (Remote) access to systems is possible from anywhere on the globe. However, this implies that there have to be technical solutions to detect, identify and acknowledge entities -people and machines- in the networks and thus to establish an initial level of trust.
 Especially since the proliferation of appropriate use-cases, Physical Layer Security (PhySec) is becoming increasingly popular in the scientific community. Using systems' intrinsic information for security applications provides a lightweight but secure alternative to traditional computationally intensive and complex cryptography. PhySec is therefore not only suitable for the IIoT and the multitude of resource-limited devices and sensors, it also opens up alternatives in terms of scalability and efficiency. Moreover, it provides security aspects regarding the entropy H and Perfect Forward Secrecy (PFS).
 Therefore, this work provides insight into three major branches of PhySec: i) Human - Physically Unclonable Functions (PUFs) ii) silicon/electrical - PUFs, and iii) Channel-PUFs. Based on the PUF operating principle, the silicon derivatives consider the electrical properties of semiconductors. Individual and uninfluenceable deviations during the manufacturing process result in component-specific behavior, which is described in particular for Static- and Dynamic Random Access Memory (S-/DRAM). Following this PUF principle, human characteristics -biological, physiological and behavioral features-, are used to recognize and authenticate them. With respect to the wireless channel, the characteristic properties of electromagnetic wave propagation and the influences on the wireless channel -diffraction, reflection, refraction and scattering-, are used to achieve symmetric encryption of the channel.
 In addition to the "conventional" wireless PhySec, especially the development of the Sixth Generation (6G) Wireless Systems, opens up a wide range of possibilities in terms of PhySec, for example in relation to Visible Light Communication (VLC), Reconfigurable Intelligent Surfaces (RIS) and in general the application of frequencies in the (sub)THz range.
 Thus, the work provides an overview of PhySec fields of application in all areas of the IIoT: in terms of humans, machines, and the transmission channel.

Room-Temperature Phosphorescence and Low-Energy Induced Direct Triplet Excitation of Alq3 Engineered Crystals.

Crystal engineering is a practical approach for tailoring material properties. This approach has been widely studied for modulating optical and electrical properties of semiconductors. However, the properties of organic molecular crystals are difficult to control following a similar engineering route. In this Letter, we demonstrate that engineered crystals of Alq3 and Ir(ppy)3 complexes, which are commonly used in organic light-emitting technologies, possess intriguing functional properties. Specifically, these structures not only process efficient low-energy induced triplet excitation directly from the ground state of Alq3 but also can show strong emission at the Alq3 triplet energy level at room temperatures. We associate these phenomena with local deformations of the host matrix around the guest molecules, which in turn lead to a stronger host-guest triplet-triplet coupling and spin-orbital mixing.

Effect of swift heavy 86Kr30+ ions irradiation on optical and electrical properties of p-type transparent Ni-doped CuAlO2 films

Swift heavy ion (SHI) irradiation is an effective approach to modulate the structure, optical and electrical properties of semiconductors. Herein, we present the influence of 86Kr30+ ions irradiation on optical and electrical properties of p-type transparent oxide semiconductor Ni-doped CuAlO2 films prepared by sol–gel method. The results reveal that Ni-doping inhibits the amorphization of CuAlO2 films during swift heavy ions irradiation and decreases the surface roughness of SHI-irradiated Ni-doped CuAlO2 films. However, SHI-irradiated Ni-doped CuAlO2 films exhibit higher optical transmittance (74%) and lower electrical resistivity (11.5 Ω cm), which corresponds to a decrease of two orders of magnitude due to the generation of a large number of carriers. In addition, SHI-irradiated Ni-doped CuAlO2 film renders photosensitive behavior and a reduced electrical resistivity of 7.4 Ω cm is achieved under UV illumination. The superior optical and electrical properties of SHI-irradiated Ni-doped CuAlO2 films can be ascribed to the thermal spike effect of high-energy ions.

Studying the effective of conductor polymer substrate on the electrical properties of semiconductors

This research includes depositionof thin film of semiconductor, CdSe by vaccum evaporation on conductor polymers substrate to the poly aniline where, the polymer deposition on the glass substrats by polymerization oxidation tests polymeric films and studied the structural and optical properties through it,s IR and UV-Vis , XRD addition to thin film CdSe, on of the glass substrate and on the substrate of polymer poly-aniline and when XRD tests was observed to improve the properties of synthetic tests as well as the semiconductor Hall effect proved to improve the electrical properties significantly

First‐Principles Modeling of Point Defects and Complexes in Thin‐Film Solar‐Cell Absorber CuInSe2

Point defects and complexes may affect significantly physical, optical, and electrical properties of semiconductors. The Cu(In,Ga)Se2 alloy is an absorber material for low‐cost thin‐film solar cells. Several recently published computational investigations show contradicting results for important point defects such as copper antisite substituting indium (CuIn), indium vacancy (VIn), and complexes of point defects in CuInSe2. In the present work effects of the most important computational parameters are studied especially on the formation energies of point defects. Moreover, related to defect identification by the help of their calculated properties possible explanations are discussed for the three acceptors, occuring in photoluminescence measurements of Cu‐rich samples. Finally, new insight into comparison between theoretical and experimental results is presented in the case of varying chemical potentials and of formation of secondary phases.

Studying the effective of conductor polymer substrate on the electrical properties of semiconductors

This research includes depositionof thin film of semiconductor, CdSe by vaccum evaporation on conductor polymers substrate to the poly aniline where, the polymer deposition on the glass substrats by polymerization oxidation tests polymeric films and studied the structural and optical properties through it,s IR and UV-Vis , XRD addition to thin film CdSe, on of the glass substrate and on the substrate of polymer poly-aniline and when XRD tests was observed to improve the properties of synthetic tests as well as the semiconductor Hall effect proved to improve the electrical properties significantly

Deep UV resonance Raman spectroscopic study on electron‐phonon coupling in hexagonal III‐nitride wide bandgap semiconductors

Electron–phonon coupling (EPC) is an important issue in semiconductor physics because of its significant influence on the optical and electrical properties of semiconductors. In this work, the EPC in wide bandgap semiconductors including hexagonal BN and AlN was studied by deep UV resonance Raman spectroscopy. Up to fourth‐order LO phonons are observed in the resonance Raman spectrum of hexagonal AlN. By contrast, only the prominent emission band near the band‐edge and the Raman band attributed to E2g mode are detected for hexagonal BN with deep UV resonance excitation. The different behavior in resonant Raman scattering between the III‐nitrides reflects their large difference in EPC. The mechanism for EPC in hexagonal BN is the short‐range deformation interaction, while that in hexagonal AlN is mainly associated with the weak long‐range Fröhlich interaction. Copyright © 2016 John Wiley & Sons, Ltd.

High Quality SiO2 Obtained From Diluted SOG for Low Temperature TFT Fabrication Process

Currently, the flexible electronics research field is of high interest because of the development of low cost products, such as solar cells and LCDs. Low temperature deposition processes are required in order to use flexible substrates. Nevertheless, the performance of the electronic devices built at temperatures below 350°C is not as good as in CMOS technology. Thus, physical and electrical properties of semiconductor and insulator materials deposited at these low temperatures must be improved. In this work, characterization of SiO2 annealed at 200°C obtained from diluted Spin On Glass (SOG) is presented. The optical and electrical characterization showed that the refractive index (n) and dielectric constant (k) values are similar to those of thermally grown SiO2. TFTs based on a-SiGe:H were fabricated to demonstrate the quality of the dielectric here obtained

Quantification of Phase Compositions Present in the System [(NiO)x].[(CoO)1-x].[(Al2O3)], 0.05 ≤ X ≤ 0.95, and the Effect in the Electrical Properties of Semiconductor as a Consequence of the CO+2 Variation

In this work were investigated the systems-NiOx-CoO1-x-Al2O3 using X-ray diffraction of the powder, which identified and quantified to phase in the sample was performed through the Rietveld method. The insertion of nickel oxide in the system obeyed the proportions of molar fraction of 0,05, 0,30, 0,50, 0,70 and 0,95 (x). Analyses were realized on samples which were treated at the temperature 1773K. From the results of refinement of spinel phase structure, was analyzed the relationship between lattice parameter refinement and the substitution of Co+2 ion by Ni+2ion in the structure. The electrical resistivity dc was observed as a respect to temperature and the results appears a decrease of resistivity when were simultaneously increased the temperature. It was observed that the conduction mechanism was the same in all samples and the results for activation energy, characterized like electron hopping, it due exchange setting the ion Co+2 D Co+3.

Observation of Polycrystalline Solar Cell Using a Laser-SQUID Microscope

Laser-SQUID microscopy is a technique for nondestructive inspection of the electrical properties of semiconductors. In laser-SQUID microscopy, a photocurrent is induced by a laser with an energy larger than the band gap of the semiconductor sample. The magnetic field induced by this photocurrent is detected by a SQUID. In our experiment the laser was focused on the surface of the sample, and a high-temperature superconducting SQUID was positioned behind the sample to detect the magnetic field from the photocurrent. The sample was raster scanned while the relative position of the SQUID and laser spot was fixed. The sample used was a commercially available polycrystalline silicon solar cell containing a p-n junction. It had several line electrodes and a transport electrode layer on the surface, and the reverse side was covered with a metal electrode. We studied a piece of this polycrystalline solar cell using a 1065 nm laser. Magnetic field induced by the laser was observed successfully. The produced image shows the inhomogeneity of the solar cell.

Cumulation of de broglie waves of electrons, endoions and endoelectrons of fullerenes, and resonances in the properties of nanocomposite materials with spatial charge layers

The cumulation of de Broglie waves of electrons in hollow molecules (for example, C60) has been investigated. The existence of negatively charged endoions of fullerenes with trapped electrons in the inner cavity (endoelectrons) is proved. The Schrodinger (Helmholtz) stationary equation for hollow polarized molecules is solved analytically. An endoelectron has a positive total energy, but, because of the polarization forces, it is localized (constantly cumulating) in the center of the hollow spherically symmetric molecule (C60). The analytically calculated Eigen ϕ-function and eigen energy determine the probability of finding an electron in the cavity of a hollow molecule. The Eigen energy of a quantum cavity (C60) is compared with experimental studies of cross sections of electrons attachment to C60 dependencies on the electron energy. The importance of the polarization hollow molecules in the stabilization of the fullerene endoions with endoelectrons (with energies from 0.2 to 12 eV) is proved. The effect of the cumulation of electrons in the hollow of the molecule (the trap for electrons) can be used to control the concentration of the charge carriers, the thermal and electrical properties of semiconductors, and the hardening of materials with free electrons. The quantum properties of polarized cavities could cause the variation of the parameters of nanocomposites with a concentration of quantum modifiers (C60).

Towards Fibered Electronics: Materials and Devices

In this paper, we present a synthetic review of the evolution of fibered electronics. Starting from inorganic materials used as coating layers for flexible yarns, and arriving at organic semiconductors, several attempts to obtain an active device in the form of a textile yarn have been presented in recent years and are described here. The challenge is to provide the basis for a new kind of electronic technology that combines the electrical properties of semiconductors (and the functions performed by active electronic devices) with the mechanical properties needed for textile technology. A further issue is to find the possibility of an easy and cost-effective fabrication of such structures. Finally, a perspective on the future promising evolutions of this field is also given.

On the possibilities of the use of phthalocyanines in photovoltaic conversion

The electrical properties of semiconductor and semimetal composites (containing CuPc and different carbon blacks) were described. Their properties may be varied in a wide range, dependently on carbon black type and preparation conditions. We expect that the photovoltaic properties of the materials can be applied for photovoltaic conversion and we discuss possibility of their practical utilisation.

Field and potential of fractal–Cantorian structures and El Naschie’s [formula omitted] theory

In this paper the complex description of conservative forces of fractal fields in the Euclidean space is presented. The physical quantities used for the description of different properties of physical reality (electrical, gravitational, thermal, acoustic, etc.) are defined. The mathematic of fractal–Cantorian geometry is used for the description of properties of the electrical field of systems with different mass distribution, electrical properties of semiconductors, thermal properties of ideal gas and properties of high-energy elementary particles following El Naschie’s E (∞) theory.

Surface photovoltage spectroscopy of semiconductor structures: at the crossroads of physics, chemistry and electrical engineering

AbstractThe possibility of obtaining a detailed picture of the electronic structure makes surface photovoltage spectroscopy (SPS) eminently suitable for bridging the gap between the chemical, physical, optical and electrical properties of semiconductors. In SPS, changes in band bending (both at the free semiconductor surface and at buried interfaces) are monitored as a function of external illumination. Surface photovoltage spectroscopy can provide detailed, quantitative information on bulk properties (e.g. bandgap and type, carrier diffusion length and lifetime) and can be used for complete construction of surface and interface band diagrams, including the measurement of energy levels in quantum structures. A particular strength is that a comprehensive analysis of surface and bulk defect state distributions and properties is made possible. Measurements using SPS are contactless and non‐destructive. In addition, they can be performed both in situ and ex situ, at any reasonable temperature, on any semiconducting material, at any ambient and at any lateral resolution down to the atomic scale. This review starts with an overview of SPS‐related surface and interface theory, describes the SPS experimental set‐up and presents applications for surface and interface characterization of a wide variety of materials and structures, cross‐correlating them with other methodologies. Copyright © 2001 John Wiley & Sons, Ltd.