Kind Of Semiconductor Material Research Articles

Research status and prospect of nano silver (Ag)-modified photocatalytic materials for degradation of organic pollutants.

Nano silver (Ag) was metallic Ag monomers with particle size to the nanoscale. Photocatalyst was a kind of semiconductor material with photocatalytic function. Loading precious metal Ag onto semiconductor surfaces by microwave, laser-induced, solvent-thermal and hydrothermal methods could capture photogenerated electrons, reduced the compounding rate of holes and photogenerated electrons during the photocatalytic process, thereby improving the electron transfer efficiency of photocatalysis and enhancing the absorption of visible light by silver nanoparticles through the plasma resonance effect. The highly reactive free radicals produced by photocatalysts were used in the organic degradation process to degrade organic matter into inorganic matter and was a faster, more efficient and less polluting method of pollutant degradation, which has attracted a lot of attention from researchers. This review discussed the modification of various types of photocatalysts by nano Ag through different methods. The photocatalytic degradation of dyes, antibiotics and persistent organic pollutants by different modified composites was also analyzed. This review covered the several ways and means in which nano Ag has modified diverse photocatalytic materials as well as the photocatalytic degradation of dyes, antibiotics and persistent organic pollutants. This review identified the drawbacks of the existing nano Ag-modified photocatalytic materials, including their low yield and lack of recyclability, and it also offered suggestions for potential future directions for their improvement. The purpose of this review was to further research on the technology of nano Ag-modified photocatalytic materials and to encourage the creation of new modified photocatalytic nanomaterials for the treatment of organic pollutant degradation.

Research progress and prospects on gas-sensitive mechanisms of semiconductor sensors.

Semiconductor materials with wide bandgaps are extensively employed for gas detection due to their advantages of low cost, high sensitivity, fast speed, excellent stability, and distinctive selectivity. Previous studies have reported on different kinds of semiconductor materials and their complex synthesis procedures. However, the research progress on gas-sensitive mechanisms seriously lags behind the performance improvement. The research route of the gas-sensing mechanism is not clear, resulting in an unclear development direction of novel sensitive materials. This review aims to summarize existing approaches and their progress on the interpretation of gas-sensing mechanisms in semiconductors, such as the calculations based on density functional theory, semiconductor physics, and in situ experiments. Ultimately, a reasonable route for the mechanism investigation has been proposed. It guides the development direction of novel materials and reduces the cost of screening highly selective materials. Overall, this review can provide helpful guidance concerning the gas-sensitive mechanism for scholars.

Hexagonal Ferrite MFe12O19 (M=Sr, Ba, Cu, Ni, Pb) Based Photocatalysts: Photoluminescence, Photocatalysis and Applications

Hexagonal ferrite (MFe12O19, M=Sr, Ba, Cu, Ni, Pb) is a kind of semiconductor material with excellent performance and an important magnetic material, with high chemical and thermal stability, low cost, simple preparation process, excellent optical, magnetic, wave-absorbing, dielectric, photoluminescence properties and catalytic activities have been widely used in broadcast communication, information storage, aerospace, automatic control, catalytic synthesis, medicine and biology and many other fields. This paper focuses on the application of MFe12O19-based ferrite in the field of photocatalysis, and further discusses the effect of preparation method on the photocatalytic activity of MFe12O19-based photocatalysts. The application of MFe12O19-based photocatalysts in the degradation of dyes, drugs and persistent organic pollutants (POPs) was deeply revealed, and the photocatalytic mechanisms of single-phase MFe12O19, ion-doped MFe12O19 and MFe12O19-based composite photocatalysts were also explored. The relationship between photocatalytic activity and photoluminescence properties of MFe12O19-based photocatalysts have also been investigated. This review points out the direction for further research on the application of MFe12O19-based photocatalysts in the field of photocatalysis.

Engineering in SnS-Based Solar Cell for an Efficient Device with Nickel Oxide (NiO) as the Hole Transport Layer

Due to the versatility, non-toxicity and earth abundancy of raw material, SnS has considered a very useful semiconductor material and the harvesting of photovoltaic energy from this kind of semiconductor material is comparatively easier than others since it is highly efficient and cost-effective. The simulation of a unique combination of device structure (ITO/SnO2/SnS/NiO/Mo) has been done and found to be worthful. Past work is quite good but unable to achieve the standard of enhanced open-circuit voltage along with the power conversing efficiency as well. The use of Hole Transport Layer (HTL) has been remarkable too since surface recombination has fallen sharply. The PCE hiked by 25% to 27.62% regardless of it is practically unattainable but in reality, it will prove as a milestone in this area if and only if we are using HTL as well. The different HTL layer has been studied for the proposed device structure and elaborated well. For the benefit of mankind, it is completely low cost and useable along with quite good performance.

Photon Recycling in Semiconductor Thin Films and Devices.

Photon recycling (PR) plays an important role in the study of semiconductor materials and impacts the properties of their optoelectronic applications. However, PR has not been investigated comprehensively and it has not been demonstrated experimentally in many different kinds of semiconductor materials and devices. In this review paper, first, the authors introduce the background of PR and describe how this phenomenon was originally identified in semiconductors. Then, the theory and modelling of PR is reviewed and some of the important parameters that are used to quantify PR are highlighted. Next, a variety of the methods used to achieve and characterize PR in materials and devices are discussed. Examples of how the performance parameters of different types of optoelectronic devices are affected by PR are described. Finally, a summary of the roles of PR in semiconductor materials and devices and an outlook on how PR can be used to solve existing problems and challenges in the field of optoelectronics are provided. From this review, it is apparent that PR can have a positive impact on optoelectronic device performance, and that further in‐depth theoretical and experimental studies are needed to rigorously demonstrate the advantages and importance of PR.

Study on the Photocatalytic Degradation Rate of Indoor Formaldehyde with Nano-TiO2 Coating

With the improvement of people’s living standard, diverse home decoration has become popular. However, it results in indoor hazardous gas emission, especially formaldehyde, bringing harm to people’s health. To address this issue, one positive strategy is to remove the hazardous volatile organic compounds through environment friendly nanomaterials. Nano-TiO2 is such a kind of semiconductor material, which can decompose the volatile pollutants via photocatalytic process. In this work, the removal of indoor volatile pollutants by applying home-made nano-TiO2 was studied. The dependence of treatment efficiency of indoor formaldehyde on varying flow rate, coating times, humidity and temperature was systematically investigated. As a result, the highest purification efficiency was achieved when it was coated three times at the relative humidity of 50%. The faster the flow rate, the higher the air purification efficiency. Temperature is also an important factor affecting degradation efficiency, and the degradation has peaked at 22°C. This study demonstrates the effective removal of indoor volatile organic compounds via green nano-TiO2 coating at low cost, and paves way for nanomaterials in applications of indoor environment improvement.

A photoexcited switchable tristate terahertz metamaterial absorber

In this study, we propose a photoexcited tristate terahertz metamaterial absorber which can switch between single-/single-/dual-band absorption modes in terahertz regime. The unit cell of the absorber incorporates two kinds of photosensitive semiconductor materials filled the gaps between four asymmetric right-angle wires and a cross wire. By applying different wavelengths of pump light on the absorber, two kinds of semiconductor materials can be excited to realize single-/single-/dual-band switchable absorption characteristics. The distributions of electric fields and surface currents at absorption peak frequencies under three absorption states are demonstrated to elucidate the switchable mechanism of the proposed absorber. Moreover, the absorption performance of the proposed tristate absorber is discussed under different polarization and incidence angles. The proposed structure is expected to be applied in the terahertz devices such as tunable absorbers, modulators, filters, and switches.

General Method To Define the Type of Carrier Transport Materials for Perovskite Solar Cells via Kelvin Probes Microscopy

Various kinds of semiconductor materials, organic and inorganic, served effectively as electrons or holes transport materials for perovskite solar cells (PSCs). However, their direct function has rarely been reported other than examining their effect in the final photovoltaic devices. In this work, a general and facile method was employed to determine to a point the type of carriers transferred by both SnO2 and NiO popular charge transport materials in PSCs via scanning Kelvin probes microscopy. The sign of the increment of the surface potential voltage measured tells directly whether electrons or holes were extracted by these carrier transport materials while its mapping can also provide the extraction difference between grain interiors and grain boundaries. Both MAPbI3 and CsFAMA triple cation perovskites were involved in the test with the same conclusion. Along with time-resolved photoluminescence, the extraction rate of each kind of material can be distinguished. This work definitely offers us a gener...

Solution-Processed Efficient Nanocrystal Solar Cells Based on CdTe and CdS Nanocrystals

Solution-processed CdTe nanocrystals solar cells have attracted much attention due to their low cost, low material consumption, and potential for roll-to-roll production. Among all kinds of semiconductor materials, CdS exhibits the lowest lattice mismatch with CdTe, which permits high junction quality and high device performance. In this study, high quality CdS nanocrystals were prepared by a non-injection technique with tetraethylthiuram disufide and 2,2′-dithiobisbenzothiazole as the stabilizers. Based on the CdTe and CdS nanocrystals, devices with the architecture of ITO/ZnO/CdS/CdTe/MoOx/Au were fabricated successfully by a solution process under ambient condition. The effects of annealing conditions, film thickness, and detailed device structure on the CdTe/CdS nanocrystal solar cells were investigated and discussed in detail. We demonstrate that high junction quality can be obtained by using CdS nanocrystal thin film compared to traditional CdS film via chemical bath deposition (CBD). The best device had short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF) of 17.26 mA/cm2, 0.56 V, and 52.84%, respectively, resulting in a power conversion efficiency (PCE) of 5.14%, which is significantly higher than that reported using CBD CdS as the window layer. This work provides important suggestions for the further improvement of efficiency in CdTe nanocrystal solar cells.

Bioelectronically Initiated Cyt P450s Catalysis without NADPH

The catalytic cycle of cytochrome P450s (cyt P450s) features delivery of electrons from NADPH to cyt P450 reductase (CPR) for subsequent delivery to cyt P450 heme. Attempts at bioelectronic initiation of cyt P450s catalysis have been made by replacing the electron donation from expensive NADPH by other electron donnors. 1 To this aim, an electrode-driven drug metabolism biosensors were constructed with a mixed film containing ITO nanoparticles and CYP2C9/CPR-microsomes encapsulated by chitosan (CS) on a GC electrode. The electrochemical response of the enzyme modified electrode to 4-hydroxylation of tolbutamide has been validated, which allowed rapid determination of the affinity parameter Km appat 202.84 μM. The inhibition effect of sulfaphenazole on the CYP2C9-dependent 4-hydroxylation of tolbutamide was also investigated. Quantum dots (QDs), a kind of semiconductor materials, can also act as electron donnors. Based on the photo-induced electron transfer (PET) from QDs to the hemoproteins, a photoelectrochemical biosensor for the light-controlled drug metabolism by cyt P450s was then constructed. As shown in scheme 1, the photosensitized QDs offer electrons demanded in the cyt P450 catalytic process while the electrode at appropriate bias potentials acts as an electron supplier to QDs for neutralizing the VB holes and monitors the occurrence of the light-induced catalytic process. This novel biosensor can be applied in drug discovery and development by monitoring substrate metabolism and enzyme inhibition.

Controllable Growth of Functional Gradient ZnO Material Using Chemical Vapor Deposition

As a kind of semiconductor material, the morphology of zinc oxide directly affects its physical properties. By adjusting the ratio of the reaction source and the rate of the incoming gas flow, we obtained one-dimensional nanowire and two-dimensional nanoflag-like functional gradient material (FGM) using chemical vapor deposition (CVD) method. Compared with the one-dimensional nanowires, the growth of the two-dimensional ZnO FGM not only c-oriented, but other directions are also appeared. Photoluminescence results show that the FGM has a higher visible/UV emission intensity ratio than the nanowires for several orders of magnitudes. Meanwhile, the growth mechanism of these nanostructures were discussed in details.

Investigation on the Optical Performance of Co and Al Co-Doping ZnO Films

ZnO is a novel kind of semiconductor material, which has hexagonal Wurtzite crystal structure, with a wide band-gap of 3.37eV at room temperature. It owns a large excitation binding energy of 60meV and excellent room temperature stability. ZnO has very useful properties of piezoelectricity, gas & pressure sensitivity etc. Therefore, application researches on low dimensional ZnO materials have become hot topics and significant values.In this paper, ZnO doped thin films were prepared by sol-gel method. Zn (CH3COO)2•2H2O was employed as the precursor, anhydrous alcohol was the solvent, monoethanolamine was the complexant, Co(CH3COO)2•4H2O was used as the source of the Co-dopant, Al(NO3)3•9H2O was used as the source of the Al-dopant in the experiment to yield the doped ZnO films. The sample preparation spin coating number is 6, the average grain size is in nanometer level, and the thermal treatment temperature is 450, 500, 550, 600°C, respectively. The effect of the doping proportion on the crystallization and energy band structure of the ZnO thin films were characterized by X-ray diffraction (XRD), the Infrared spectrum and the ultraviolet-visible transmission spectra (UV-Vis).The results show that the crystalline grain size of the ZnO doped films grown on glass substrates increases, since the thermal treatment temperature rise. In this paper, a best ZnO doped film was obtained at the temperature of 600°C. It preliminarily analyses that Co-doped ZnO films present a absorption peak in infrared area when the thermal treatment is at 550°C. Al or Co doped ZnO films can cause a redshift of ultraviolet absorption peaks. Energy gap is around 3.2eV when doped. The ultraviolet absorption peaks of Al-doped ZnO films will have a shift to high energy, since it has a better crystallinity.

A Novel Temperature Sensor Based on Gold Interdigital Electrodes and Nano ZnO Particles

Nano ZnO is an important kind of semiconductor materials, and it has been widely used in various single detection fields. In this paper, we prepared nano ZnO powder through direct precipitation method. We fabricated temperature sensor utilizing the interdigitated Au electrodes drop-deposited by nano ZnO powder. The response of the sensor to temperature was studied by CHI660 electrical chemical workstation. The results proved that the temperature sensor based on nano ZnO material presented sensitivity and repeatibility

Fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam method

In this paper, we introduced the fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam machine, it shows that the method of focused-ion beam can fabricate two-dimensional photonic crystal and photonic crystal device efficiently, and the quality of the fabricated photonic crystal is high. Using the focused-ion beam method, we fabricate photonic crystal wavelength division multiplexer, and its characteristics are analyzed.

Fabrication of photonic crystal on semiconductor materials by using focued ion-beam

A method of manufacturing two-dimensional photonic crystals on several kinds of semiconductor materials in near infrared region by a focused ion beam is introduced, and the corresponding fabrication results are presented and show that the obtained parameters of fabricated photonic crystals are identical with the designed ones. Using the tunable laser source, the spectra of the fabricated passive photonic crystal and the active photonic crystal are measured. The experiment demonstrates that the focused ion-beam can be used to fabricate the perfect two-dimensional photonic crystals and their devices.

Characterization of nanocrystalline-nanoporous TiO2 semiconductor thin films

NANO-SIZED semiconductor particles have been studied extensively as a new kind of semiconductor material in chemistry, physics and materials science. They exhibit fascinating photochemical and photophysical behaviour due to energy quantization and pronounced surface effects caused by decrease in particle size-displaying broad prospects of application in photoelectric...

Refraction Index and Moss Rule of Zn 1-x Fe x Se Thin Films

1 Introduction ZnSe is a kind of semiconductor materials with a broad band gap of direct transition, and is suitable for making photoelectric devices in the short-wavelength of visible light. It is also a kind of good infrared window materials. In recent years, investigations of diluted magnetic semiconductors (DMS) based on ZnSe, e. g. Zn_(1-x)Fe_xSe, Zn_(1-x)Mn_xSe, have been developed rapidly, because they possess the singular magnetic and optical properties. The theoretical and experimental studies show that the optical properties, such as optical absorption of DMS, are obviously influenced by the

Photoelectrochemistry with the Rotating Optical Disk Ring Electrode: III . Thermal and Photoinduced Electron Transfer in Colloidal

The rotating optical disk ring electrode (RODRE) has been successfully applied to study interfacial charge transfer phenomena in colloidal particles. In this electrode, light enters the cell through a transparent quartz disk and photogenerated species are detected at a metal (Pt) ring surrounding the transparent disk. Measurement of dark currents as a function of rotation speed allows calculation of the heterogeneous electron transfer rate constant and the average number of conduction‐band electrons per particle. Illumination of the RODRE provides, from the dependence of the photocurrent on light intensity and rotation speed, an estimate of the stability of photogenerated conduction‐band electrons, the quantum yield of photoelectron generation, and the photoelectron lifetime. The results reported clearly illustrate that the RODRE is a useful and convenient technique for studying charge transfer phenomena in colloidal suspensions of semiconductor particles. The advantage of the disk ring technique (RODRE) over the alternative disk electrode technique (ORDE) is that, for the RODRE, there is no need to use any coating material to make the ring electrode conducting, while, for the ORDE, a semitransparent layer of is applied to make the transparent surface conducting. The nature of this coat imposes limitations in the kind of semiconductor materials that can be studied.

Photocurrent spectroscopy of a strained-layer superlattice

Strained-layer superlattices (SLS's) are a new kind of semiconductor material, grown from lattice-mismatched constituents, whose electronic properties may be tailored over a wide range. We report the growth by metal-organic chemical vapor deposition of a GaAs 0.4P 0.6/GaP SLS, and the characterization of its room temperature electronic properties by photocurrent spectroscopy. The results are consistent with predictions of an effective-mass (Kronig-Penney) model.