Wire saw slicing technology has become a research hotspot in the field of slicing of brittle-and-hard materials. As an important process in semiconductor wafer processing, wire saw slicing has a crucial impact on the quality of semiconductor wafers. This paper introduces the basic theory and the research progress of wire saw slicing technology, taking the most mature silicon crystal as an example, especially the mechanical model and material removal mechanism of wire saw slicing. Then the influence of wire saw manufacturing technology and slicing process on the material is discussed. Furthermore, silicon carbide is a key material that supports the development of electric cars, clean energy and national defense industry because of its outstanding comprehensive advantages in physical properties, such as wider band gap. In this paper, the application and technological progress of wire saw slicing in silicon carbide wafer processing are reviewed. In addition, the influence of wire saw slicing on the surface quality and damage of silicon carbide crystal is analyzed. Finally, this paper points out the challenges and future development directions of wire saw slicing technology.

Compared to conventional silicon-based electronics, flexible electronic devices have been extensively studied for their unique advantages of distinguished portability, conformal contact characteristics, and human-friendly interfaces. As an important branch of flexible electronics, flexible memory has shown good application prospects in wearable devices, smart medical care, electronic skin and other fields. At the same time, with the in-depth application of 5G, artificial intelligence, the internet of things and other new generation of information technologies, the market demand for high density, non volatile, ultra-low power consumption of flexible memory continues to release, giving birth to the research boom of flexible ferroelectric memory devices. Herein, the preparation of flexible ferroelectric films and the progress of their application in memory field are reviewed. Prevailing methods for preparing flexible ferroelectric films including the van der Waals heteroepitaxy on flexible substrate, delamination of the ferroelectric films on rigid substrate by chemical etching techniques, and growth of novel 2D ferroelectric materials are summarized. The research progress of flexible ferroelectric devices applied to memories are also be discussed. Finally, the challenges and prospects of flexible ferroelectric devices in the future are briefly proposed.

Copper based sulfide photocatalysts have attracted extensive attention of researchers due to their narrow band gap, local surface plasmon resonance effect, good absorption ability to visible light, rich in reserves and non-toxic properties. However, the high recombination rate of photogenerated electrons and holes, and the low utilization efficiency of visible light hinder their application in the field of photocatalysis. Therefore, researchers have tried different modification strategies to improve their photocatalytic performance. This paper focuses on the modification strategies of copper based sulfides, mainly discusses the modification of the photocatalytic performance of copper based sulfides by morphology regulation, crystal phase regulation, and semiconductor heterojunction, etc., and analyzes the effect of different modification methods on the improvement of the photocatalytic performance. The application of copper based sulfides in the photocatalytic degradation of organic pollutants, photocatalytic splitting water for hydrogen production, photocatalytic reduction of CO2, etc. are discussed, and the development direction of copper based sulfide modification is prospected.

A method of optimizing the stability of the resonant cavity by adding an additional crystal into the laser resonant cavity is studied for the first time. The laser performance can be effectively improved by adding crystals with appropriate refractive index into the resonant cavity. In this study, a Nd3+∶Gd0.1Y0.9AlO3 (Nd∶GYAP) crystal laser device was built, and LBO crystal were added into the resonant cavity. The effects of LBO crystal on the laser properties of b-cut and c-cut crystals were compared respectively. The laser performance with and without LBO crystal was characterized in terms of output power, laser wavelength, beam quality and polarization characteristics. When LBO crystal is inserted into the laser resonant cavity, the slope efficiency of b-cut Nd∶GYAP increases from 18.9% to 24.3%, and that of c-cut Nd∶GYAP increases from 2.87% to 10.07% without changing the spectrum and beam quality. The maximum output power of b-cut crystal increases from 0.931 W to 1.254 W, and that of c-cut crystal increases from 63 mW to 134 mW. However, the polarization of the output laser deflects to some extent due to the optical rotation effect. This research provides a way to improve the slope efficiency and output power of lasers in the cases of the cavity length must be extended such as tuning and mode-locking operations.

The 76 mm×76 mm LaBr3 crystal doped with CeCl3 was grown by modified Bridgman technique. The crystal was cut and ground to 76 mm×15 mm, and packed in a housing to prevent hygroscopic effects. The entrance window was comprised of a 200 μm thick Be sheet. The energy resolution of package is 55% under 5.9 keV gamma-ray excitation. The scintillation performance of the package was characterized before and after mechanical test (1 000 g impact and 14.12 g random vibration), thermal vacuum test (-40~+50 ℃, ≤1.3×10-3 Pa), and irradiation test (160 krad dose of 60Co irradiation). The results show that there is no change in the appearance of crystal. The energy resolution of the package changes from 5.30% to 4.89% under 662 keV gamma-ray excitation, the light output loss is 0.2%.

In the optical parametric oscillator (OPO) based on CdSe crystal, a large amount of waste heat is generated when the pump laser passes through the crystal, resulting in a significant thermal lens effect in CdSe crystal, which causes the spot radius of the pump laser smaller inside the crystal, and finally reduces the damage threshold of the crystal and the output power of the OPO. The thermal lens effect simulation of CdSe crystal pumped by high frequency pulsed laser is completed by COMSOL software in this paper. Through parameter optimization, it is found that the convection coefficient is inversely proportional to the maximum temperature of the crystal, directly proportional to the spot radius of the back face and focus of the crystal, and the focus position tends to be stable with the increase of convection coefficient. The single pulse energy and repetition frequency are directly proportional to the maximum temperature of the crystal and the spot radius of the focus, and inversely proportional to the spot radius and the focus position at the back end of the crystal. The collimated laser spot radius is inversely proportional to the maximum temperature of the crystal, and directly proportional to the spot radius, focus position and spot radius of the back end of the crystal. This study solves the problem that the laser spot radius at the back end of CdSe OPO crystal is difficult to measure directly, and provides a theoretical basis for optimizing the thermal lens effect of CdSe crystal.

Hg3In2Te6 (MIT for short) is a stable phase corresponding to x=0.5 in the Ⅱ-Ⅵ/Ⅲ-Ⅵ compound semiconductor Hg(3-3x)In2xTe3. In this paper, the stability and doping efficiency of Au in MIT were systematically investigated using the first-principles method. The results show that Au-Te bonds has polar covalent bond characteristics similar to that of Hg-Te bonds in MIT, indicating that Au has certain doping stability in MIT. In addition, it is found that there are amphoteric doping properties of Au in MIT: Au exhibits acceptor properties in AuHg and AuIn systems, and the Au-5d electron orbital resonates with the Te-5p electron orbital at the top of the valence band and -4 eV position, respectively, forming acceptor defect levels. While Au exhibits donor characteristics in AuTe and AuI systems, Au-5d resonates with Hg-6s and In-5s electron orbitals at the conduction band bottom, forming donor defect levels. It is worth noting that under Hg-rich conditions, there will be a self-compensation effect between AuI, AuTe and AuHg systems, and the Fermi level will be pinned at the top of valence band, while under Te-rich conditions, the self-compensation effect will be effectively eliminated.

In this paper, the diffraction efficiency as a function of grating writing angle in LN∶Fe, Hf crystals was studied, and the relationship curve was fitted and analyzed. It is found that the bulk photovoltaic coefficient κ increases significantly when the Hf-doping concentration exceeds the threshold. The dramatic increase of the coefficient κ to the fact that the Hf-doping eliminates the intrinsic defects in the crystal and the perfection of the lattice environment enhances the photovoltaic coefficient k of the Fe ions remaining at Li sites. The experimental results also show that the concentration of photorefractive centers is about 14.5 ppm (1 ppm=10-6) in LN∶Fe, Hf crystals, that is, 4.8% of the Fe ions still “remain” in the Li site even though the Hf-doping concentration already exceeds the threshold, and that these Fe ions can cause sufficiently strong photorefractive effect and become the dominant photorefractive centers in the LN crystal. In addition, the possibility of Fe ion occupation in LN lattice from the perspective of impurity-hydroxyl defect complex was discussed.

As a promising heat dissipation material, diamond is wildly used in high power semiconductor devices, lasers, microwave devices and large-scale integrated circuit fields. The accurate local temperature measurement of diamond to evaluate its heat dissipation performance has become an important research topic. In this paper, Raman spectroscopy was employed to investigate the Raman spectra (TO mode) characteristics of diamond in the temperature range of 228 to 678 K. The one-to-one correspondence between Raman peak position, full width at half maximum (FWHM) and temperature of different doped diamond samples was established. The contributions of thermal expansion, three phonons and four phonons to Raman peak position at variable temperatures were analyzed by theoretical model calculation. The results show that there is no significant difference among the Raman spectra of different doped samples of HTHP and CVD. With the increase of temperature, the FWHM broadens. It is considered that the anharmonic effect caused by phonon attenuation is the determining factor, while the ionization rate, concentration and type of carriers, defects and impurities contribute partial influence. Meanwhile, the phonon lifetime is mainly affected by the anharmonic attenuation of phonons, and appears largely unaffected by impurity scattering. This study shed light on a non-destructive, non-contact, high spatial resolution method to the temperature measurement for diamond materials.

After adjusting the component parameters of the designed AlGaInN/InGaN DBR structure with a central wavelength of 520 nm, strain compensation was realized and the overall strain of DBR turned to 0. The transmission matrix method was used to calculate the reflectance spectra of Al0.7Ga0.3-xInxN/InGaN DBR, Al0.8Ga0.2-xInxN/InGaN DBR, and Al0.9Ga0.1-xInxN/InGaN DBR. By comparing the structure parameters of DBR, the structure and reflection performance of DBR are optimized. First, high and low refractive index layer growth sequence was compared for Al0.8Ga0.14In0.06N/In0.123Ga0.877N DBR. For DBR with first grown high refractive index layer, the reflectance is as high as 99.61%, while for DBR first grown low refractive index layer, the reflectance is only 97.73%. Then, by comparing the odd-layer DBR and even-layer DBR, it is found that the reflection spectra of the two layers are almost identical, and there is no significant difference. By comparing the periods of DBR, it is found that the reflectance increases obviously with the increase of period number between 20 and 30 pairs, while the reflectance increases slowly with the increase of period number between 30 and 40 pairs. At last, the influence of the material components on the reflection spectrum is studied. It is found that the DBR with high Al component has a large refractive index difference and better reflection performance, while the lower content of In in the same Al component AlGaInN, the higher the reflectivity. Due to the possible deviation of thickness and component in the preparation of DBR, the changes of reflection spectra resulted from the deviation of thickness and components were simulated. It is found that the reflection spectrum is red-shifted or blue-shifted by 4 nm to 5 nm when the layer thickness of high or low refractive index is increased or decreased by 1 nm. While the component deviations caused significant changes in high anti-band bandwidth and reflectivity at central wavelength. The study in this paper provides some theoretical reference for the design and preparation of AlGaInN/InGaN DBR.

In this paper, Cu2ZnSnSe4(CZTSe) thin films were prepared by solution method. A small amount of Ge was added into the solution and the effect of Ge incorporation on the properties of CZTSe thin films and devices was investigated. For comparison, two sets of CZTSe thin films and corresponding solar cells, namely CZTSe without Ge and CZTSe with a small amount of Ge［Cu2Zn(Sn, Ge)Se4, CZTGSe］were prepared. The crystal structure, phase purity, surface morphology, and carrier concentration of the prepared thin films, as well as the electrical properties of the complete devices were characterized and analyzed by X-ray diffractometer (XRD), Raman spectra, scanning electron microscopy (SEM), Hall measure system, current voltage (J-V) curve, and external quantum efficiency (EQE) tests, respectively. The results demonstrate that Ge incorporation into the CZTSe film promotes the crystallization mainly due to the formation of Ge-Se liquid flux during the selenization process, reduces the number of grain boundaries and the minority carriers recombination at the grain boundaries and enhances the carrier lifetime. In addition, partial substitution of Ge for Sn reduces the density of defect states associated with Sn, increases the energy band gap and open circuit voltage, improves the series and parallel resistance, and thus increases the fill factor. Finally, the prepared CZTGSe thin film solar cells reach a photoelectric conversion efficiency of 8.83% with open circuit voltage of 513.2 mV, short circuit current of 27.47 mA/cm2 and fill factor of 62.68%.

Mg3Bi2/Mg2Sn nanocomposite films were prepared by high vacuum magetron sputtering with alternately sputtering on single crystalline Si substrate containing SiO2 layer of 500 nm thickness using high-purity Mg target and self-made Mg-Bi-Sn alloy target. The crystal structure and phase composition of the deposited films were determined by X-ray diffraction (XRD) patterns. The morphology and surface chemical composition of the deposited films were observed, measured and analyzed by field emission scanning electron microscopy (FESEM) and energy dispersive spectrum (EDS), respectively. The carrier concentration and mobility of the deposited films were obtained by Hall experiment. The electrical conductivity and Seebeck coefficient of the deposited films were measured by Seebeck/resistance measure and analysis system. The results show that the nanocomposite film is composed of Mg3Bi2 and Mg2Sn phase. Measurement and calculation of half height width of the diffraction peak for Mg2Sn phase show that the grain size of Mg2Sn phase in the deposited films is 13 nm to 16 nm. With the increase of Mg2Sn phase contents, the carrier concentration increases and the mobility decreases at room temperature. The phase interface is the barrier to carrier transmission, the carrier mobility decreases because of more phase interface. In the whole measured temperature range, the Seebeck coefficient increases and the conductivity decreases with the increase of Mg2Sn phase contents in the deposited film. The energy filtering effect at the phase interface causes carriers with lower energy to be filtered out, and the energy of carriers in the film is more concentrated, namely, the dp(E)/dE increases, causing Seebeck coefficient increases with the increase of phase interface. The film with 28.22% Mg2Sn atomic content of phase can obtain the highest power factor value of 1.2 mW·m-1·K-2 at 155 ℃. The power factor of Mg3Bi2 film can be significantly improved by adding proper amount of Mg2Sn second phase into Mg3Bi2 film, forming nanocomposite films.

Cu2ZnSnS4 thin films have attracted much attention due to their abundant elemental crust content, non-toxic and excellent photoelectric properties. In this paper, Cu2(CdxZn1-x)SnS4 (CCZTS) thin films were prepared by partially replacing Zn with Cd based on nano-ink method. The effects of annealing time and post-annealing temperature on the properties of the thin films and solar cells were studied. The results show that the prepared thin films are CCZTS phase without other heterogeneous phases, and the surface of thin films is flat and dense with good crystallinity. With the increase of annealing time, the grain size of thin film increases, the quality of pn junction of the thin film solar cells is improved, and performance of the solar cells is also improved. The effect of elemental diffusion in the absorber layer on the performance of solar cells after post-annealing was analyzed, and the performance of solar cell was improved when Cd elements formed a gradient distribution. With the increase of post-annealing temperature, both of the solar cell performance and pn junction quality first increase and then decrease. The solar cell conversion efficiency is optimal (3.13%) after 300 ℃ post-annealing treatment.

Perovskite solar cells (PSCs) have achieved significant progress in recent years. However, to further reduce the cost and improve stability of PSCs, development of low-temperature processed, stable and efficient inorganic hole-transport layer is mandatory. In this work, inorganic CuS based PSCs were simulated with the simulation software SCAPS-1D. The effects of thickness and defect density of the absorber, defect densities of the interfaces, and electron affinity of the hole-transport layer (HTL) on the performance of PSCs were studied. Results show that when perovskite thickness is 400 nm, the defect densities of the absorber and the interfaces are both under 10-16 cm-3, and the electron affinity of CuS is 3.3 eV, the PSCs yield higher performance with open circuit voltage (Voc) of 1.07 V, current density (Jsc) of 22.72 mA/cm2, fill factor (FF) of 0.85, and photoelectric conversion efficiency (PCE) of 20.64%. This work provides theoretical guidance for the preparation of high-performance PSCs based on CuS HTLs.

The inner wall of the quartz crucible for continuous Czocharlski will form more bubbles with the increase of Czocharlski times, and it is easy to generate dislocations in the crystal and the erosive silicon melt, which will cause the crucible to dissolve and corrode over time. In order to study the effect of the interaction of erosive silicon melt with bubbles on the crucible, in situ observations of the performance of quartz crucibles are expected. However, the extremely high temperature environment inside single crystal furnaces makes it difficult to investigate their interiors experimentally. In this paper, the pore-crack on the inner surface of the quartz crucible are taken as the research object, and the finite element simulation is used to obtain the stress intensity factor values of different pore shapes, crack shapes and crack inclination angles of the quartz crucible under high temperature cyclic loading at different Czocharlski stages. The results show that with the increase of the crack inclination angle, the KΙ value shows a trend of gradually decreasing, the KⅢ value shows a trend of first increasing and then decreasing, and the KⅢ value is symmetrical distributed along 45°; furthermore, with the increase of the pore depth/diameter ratio, KΙ value shows a decreasing trend, and the rate of reduction when the depth/diameter ratio is equal to 1 as the boundary has a significant increase, KⅢ is much smaller than KΙ value, indicating that the dominant form of cracking is type Ⅰ; the crack shape ratio has a significant impact on the value of KΙ or KⅢ, and the smaller the shape ratio, the greater the value of the stress intensity factor at the crack tip; when the inclination angle is 0°, the total stress intensity factor K value is the largest, which will make the crack most likely to expand and the most harmful to the quartz crucible. Finally, in the case of continuous Czocharlski, the total stress intensity factor of the crown growth process is always greater than that of the equal diameter growth, cone and cooling growth process. Simulation results bring certain theoretical guiding significance for production.

As the initial stage of crystallization, nucleation directly affects the structure, chirality, purity, crystal forms and particle size distribution of crystal products. However, due to the random nature of nucleation, experimental methods are not only time-consuming and laborious, but also difficult to understand the molecular interactions. In this paper, ethyl paraben (EP), propyl paraben (PP) and butyl paraben (BP) with similar structure were selected as model substances, and the binding energies of single solute and single solvent molecules of EP, PP and BP in four different organic solvents (ethanol, ethyl acetate, acetone, acetonitrile) were calculated. The interaction of EP, PP and BP with each solvent decreases in the following order: ethanol>ethyl acetate>acetone>acetonitrile. Therefore, it can be predicted that EP, PP and BP nucleate slowest in ethanol, slower in ethyl acetate and acetone, and fastest in acetonitrile. When the solvent is the same, EP is the most difficult to nucleate, followed by PP, and BP is easy to nucleate. The predicted results are consistent with the experimental results. This study proves that the solute-solvent (1∶1) model can predict the difficulty of nucleation, which is conducive to solvent screening and improve experimental efficiency.

Photodynamic antimicrobial therapy (PDAT) is a new method for the treatment of microbial infections. However, there have been few reports on the photodynamic antimicrobial activity of corrole, which has a significant advantage in the treatment of photodynamic antitumor activity. In this study, mono-hydroxyl corrole named 10-(4-hydroxyphenyl)-5, 15-bis(pentafluorophenyl) corrole (P-OH) was synthesized. What’s more, its crystal structure and photodynamic antibacterial activity were also explored. The results indicate that mono-hydroxyl corrole belongs to orthorhombic crystal system and shows good photodynamic antibacterial activity. When the concentration of the drug is more than 2MIC, the bacteriostatic effect is showed. Whereas, the concentration of drug less than 2MIC shows antibacterial effect. The minimum bactericidal concentration and minimum inhibitory concentration of the drug are lower than porphyrin, it is a good photodynamic antibacterial photosensitizer.

The study on the oxidation process of magnesium (Mg) alloy and corresponding control mechanism by in situ real-time observation has been a hotspot in the field of surface treatment for magnesium. In this study, magnesium film was kept for 10 h at 400 ℃ in a furnace, and the faceted Mg nanopores were prepared by focused electron beam technology under a transmission electron microscope (TEM). The slow oxidation and growth dynamics of the surface lattices at the vicinity of Mg nanopores under trace oxygen condition were observed using in situ high-resolution transmission electron microscopy techniques, while the corresponding mechanisms were also researched. The results show that the oxidation proceeds via an adatom process, resulting in the diffusion of Mg atoms from the substrate to the subsurface of oxides, and the oxidation growth process is mainly achieved via layer-by-layer epitaxial growth of MgO. The faceted morphology enclosed by {200} lattice planes attributes to the typical anisotropic growth. The study on the roles of defects in the process of oxidation growth shows that the defects, such as vacancies and dislocatios, promote the oxidation process, whereas the large-angle grain boundary of the twinning inhibits the rotation or migration of the grain boundary, which is conducive to improve the corrosion resistance of magnesium alloy.

In this paper, CaCl2 and KH2PO4 were used as raw materials, Na2EDTA·2H2O as chelating agent, and NH3·H2O was used to adjust pH value of the solution, the calcium-phosphate coatings on titanium substrate were prepared via hydrothermal method, and the effects of filling condition (FC) (16%~64%) and pH value (3.5~6.0) on morphology and phase constitutions of the coatings were systematically investigated. The results show that: when the pH value is 3.5 and 4.0, the coatings are mainly platelet-like calcium hydrogen phosphate (DCPA) (P1) at different FC, and FC has no remarkable effect on phase constitution of the coatings; when the pH value is 4.5 and 5.0, dandelion-like hydroxyapatite (HAP) (P63/m) are easily found at lower FC, and with the increase of FC, the coating changes from dandelion-like HAP to platelet-like DCPA; when the pH value is of 5.5 and 6.0, the coatings are mainly dandelion-like HAP at different FC, and with the increase of FC, the crystallinity of HAP increases, while with the increase of pH value, the diameter of dandelion-like HAP decreases. Otherwise, the wettability of the three typical coatings (i.e., the dandelion-like HAP, the platelet-like DCPA, and the mix of (HAP+DCPA)) show much better wettability than the titanium substrate, this indicates that the calcium-phosphate coatings would benefit the future osseointegration. Meanwhile, the formation mechanisms of different kinds of coatings were discussed.