By virtue of their complete spin polarization at the Fermi level, two-dimensional (2D) magnetic half-metallic materials are emerging as one of the latest wonder building blocks for spintronic ...applications. Using first-principles calculations, we explored how vacancy defects affect the electronic structure and magnetic properties of CrSI semiconductor monolayer. Our results indicate that the magnetic semiconductor monolayer becomes metallic with the presence of single Cr vacancies, VCr, or paired vacancies made up of Cr and nearby S atoms, VCr-S, while by introducing VS, VI, VCr-I and VS-I vacancies, the monolayer becomes a half-metallic ferromagnet with Curie temperature TC above room temperature. Compared with the pristine case that exhibits an intrinsic in-plane magnetic anisotropy with an easy axis along the 100 direction, the six types of vacancies considered in this study either enhance the in-plane anisotropy or switch it to out-of-plane. Our work implies that vacancy engineering could be a viable approach for achieving both half-metallicity and perpendicular magnetic anisotropy in structurally similar magnetic semiconductor monolayers as well as in relevant designer van der Waals heterostructures for 2D spintronic applications.
•Pristine CrSI monolayer is a 2D magnetic semiconductor with a total magnetic moment Mtot of 3.000 μB per unit cell.•Pristine CrSI monolayer has Curie temperature well above room temperature.•We predict vacancy-induced half-metallicity in magnetic CrSI semiconductor monolayer.•The six types of vacancies considered can either enhance the in-plane anisotropy or switch it to out-of-plane.
Traditionally, condition monitoring of power semiconductor modules has been based on electrical measurements. Acoustic emission has been utilized for condition monitoring in many other applications, ...but is an unknown phenomenon in power semiconductor modules. In this paper, the authors present an experimental setup used to show that acoustic emission does occur because of the switching of power semiconductor components. An analysis based on propagation delays is used to determine the source of the acoustic emission.
The nonionizing energy loss (NIEL) concept, introduced more than 40 years ago, is still used to characterize the damage generated by different particles and <inline-formula> <tex-math ...notation="LaTeX">\gamma </tex-math></inline-formula>-rays. Its continuing relevance is due to the experimentally established scaling in the creation rate of defects by radiation of different types. NIEL calculations are quite simple, based on classical physics. We thus name them classical NIEL, NIEL c . Their calculation depends on an <inline-formula> <tex-math notation="LaTeX">a </tex-math></inline-formula> priori known <inline-formula> <tex-math notation="LaTeX">E_{d} </tex-math></inline-formula>-displacement threshold energy in monoatomic materials. For the compound semiconductor materials studied here, Ga<inline-formula> <tex-math notation="LaTeX">X </tex-math></inline-formula> and In<inline-formula> <tex-math notation="LaTeX">X </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">X </tex-math></inline-formula> are the cations N, P, As, Sb, the experimental <inline-formula> <tex-math notation="LaTeX">E_{d} </tex-math></inline-formula> values vary over a wide range and only approximate values for NIEL c can be calculated. Thanks to some recent studies carried out using the molecular dynamic (MD) method, the NIEL values were estimated using atomic scale calculations. Consequently, we can now compare NIEL c with more precise data. These data also include the "dynamic" behavior of the NIEL, which is related to the annealing of the damage (like Frenkel pair recombination) and the generation of extended crystalline defects. The NIEL calculated using the MD method is referred to in the literature as NIEL eff . A detailed comparison between NIEL c and NIEL eff as a function of electron and proton energies is made here. It shows that the difference between the two quantities is not large and cannot influence the dependence of NIEL on temperature and different radiation types. Both yield similar results in calculating the effect of displacement damage. As an additional use of NIEL c , we analyze its application to estimate the relative tolerance of the different members of the Ga<inline-formula> <tex-math notation="LaTeX">X </tex-math></inline-formula> and In<inline-formula> <tex-math notation="LaTeX">X </tex-math></inline-formula> families to radiation defects as a function of particle energies.
Optical devices based on alloying semiconductors offer a plethora of new possibilities for detection across a broad spectrum. Among these devices, nanowire‐based devices have gained much attention ...due to their remarkable specific surface area properties in terms of material synthesis, device structure, and performance. In this work, (BixIn1−x)2S3 nanowires are designed by controlling the ratio of Bi and In atoms. The atomic ratio directly affects the electronic band structure of the crystal, thereby further optimizing the performance of optoelectronic devices. According to the experimental results, Bi1.28In0.72S3 nanowire‐based photodetectors obtain the most excellent photoresponse performance. The typical device demonstrates a spectral response from deep ultraviolet (DUV 254 nm) to near‐infrared (NIR 1064 nm) and achieves a maximum dichroic ratio of photoresponse of 1.5 under polarization‐angle‐sensitive detection in the 266–808 nm range. It also exhibits a photoresponse of 10.1 A W−1 and a photodetectivity of 5.7 × 1010 Jones under 532 nm light irradiation. Additionally, the photodetector displays a fast response speed with a rise/fall time of 5/4.7 ms. Finally, “CSU” and puppy images produced by this device further demonstrate the effectiveness of alloying semiconductors in creating wide‐spectrum, high‐responsivity, fast‐response, and polarimetric‐sensitive photodetectors.
By regulating atomic proportions to achieve bandgap engineering, (BixIn1−x)2S3 nanowires with broadband, high responsivity, and angle sensitivity for optoelectronic devices with near‐ideal numerical accuracy in image recognition are obtained. Bandgap engineering can be a promising method for high‐performance photodetectors.
The field of organic electronics has been prolific in the last couple of years, leading to the design and synthesis of several molecular semiconductors presenting a mobility in excess of 10 cm2 V−1 ...s−1. However, it is also started to recently falter, as a result of doubtful mobility extractions and reduced industrial interest. This critical review addresses the community of chemists and materials scientists to share with it a critical analysis of the best performing molecular semiconductors and of the inherent charge transport physics that takes place in them. The goal is to inspire chemists and materials scientists and to give them hope that the field of molecular semiconductors for logic operations is not engaged into a dead end. To the contrary, it offers plenty of research opportunities in materials chemistry.
Organic semiconductors for logic operation are currently facing a crisis because charge carrier mobility tends to level off, the industrial interest is fading away, and more than half of transport measurements in transistors are stained by errors. However, the field remains particularly rich in opportunities for new academic and even industrial developments if fundamental issues are addressed.
The detrimental carrier recombination in semiconductors is a well-known bottleneck which limits their photocatalytic properties. This has led to intense research in understanding the mechanisms of ...carrier recombination as well as finding new ways to synthesize materials that offer efficient photocatalytic properties. Semiconductor-semiconductor heterojunctions have shown promise in this regard by providing a platform for separation of charges across the interface as well as the control over modifying the band alignment. Herein, we devise a two-step solution-based synthesis strategy to create a composite material between a wide band gap Ag2WO4 material and a narrow band gap Bi2Fe4O9 material. The Ag2WO4/Bi2Fe4O9 composite materials forms a type-2 heterojunction. The photocatalytic activity of the composite material was investigated by studying the degradation of Rhodamine-B dye in the presence of 3 wt%, 5 wt%, 7 wt%, and 9 wt% of Ag2WO4 in Bi2Fe4O9. The percentage degradation of Rhodamine-B in the presence of 7-Ag2WO4/Bi2Fe4O9 was found to be 87% in comparison to 80% in 3-, 83.4% in 5-, and 85% in 9-Ag2WO4/Bi2Fe4O9. The rate of degradation is nearly 10 times faster in 7-Ag2WO4/Bi2Fe4O9 as compared to pristine Bi2Fe4O9 and 4 times faster as compared to 3-Ag2WO4/Bi2Fe4O9. The materials also exhibit strong photostability with approximately 80.3% retention in photocatalytic efficiency after 4 initial catalytic cycles. This heterojunction owes its efficient photocatalytic activity to the peculiar band alignment of the constituent semiconductors which allows photoinduced electron transfer to occur across the interface. This phenomenon results in the separation of charges, which increases their lifetime long enough to initiate chemical transformation.
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•A revisit to semiconductor-semiconductor interface for reduced charge recombination is reported here with an unexplored composite material (Ag2WO4/Bi2Fe4O9) having considerably improved photocatalysis.•Two-step solution-based synthesis strategy to generate intimate contact between a narrow bandgap Bi2Fe4O9 material (1.9–2.1 eV) and a wide bandgap Ag2WO4 material (2.9–3.1 eV) is reported here.•The photo-catalytic dye degradation experiments on the model Rhodamine dye exhibits Kapp value of 3.53 × 10−2 min−1 which is several folds higher than Kapp values of pristine Bi2Fe4O9 (3.64 × 10−3 min−1) and Ag2WO4 (1.81 × 10−3 min−1).•The material also exhibits excellent photostability with almost 100% retention in photocatalytic efficiency after 4 initial catalytic cycles.
Transition metal telluride magnetic semiconductors were highly attractive because of their wide range of applications in different technology. In continuance, Pt-doped CoTe magnetic semiconductor was ...successfully synthesized by the hydrothermal approach and proposed as a catalyst for the electrochemical sensors. The hexagonal crystal structure, nanoflake/nanosheet morphology, and porous microstructure of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) respectively. The electrochemical sensing behavior of the modified Pt/CoTe/GCE electrode was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Observed electrochemical results infer the excellent catalytic activity of 5% Pt-doped CoTe towards dopamine and showed a maximum peak current with low peak potential when compared to other modified electrodes. The 5%Pt-doped CoTe electrode exhibits high sensitivity and a desirable limit of detection (LOD) of 25 nM. The intrinsic magnetic characteristics also evaluated for this magnetic semiconductor and demonstrate the fascinating application for spintronics devices. This finding unveils the new application of magnetic semiconductors in cost-effective electrochemical detection of biomolecules.
Bulk CuAlO2 compound has been widely studied as a p-type metal oxide semiconductor material due to the simplicity in its synthesis and use of inexpensive raw materials. The Fe doping in CuAlO2 has ...been demonstrated to enhance the electrical conductivity. An in-depth analysis of the effect of Fe doping in CuAlO2 on the carrier concentration improvement was revealed. Delafossite CuAl1−xFexO2 powders with x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.30 were synthesized by a solid-state reaction method. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) studies were used to measure the atomic-ion concentrations and the oxidation state of each element. The variations of carrier concentration corresponded with a ratio of Cu2+/Cu1+ in CuAlO2. We found that the increase of Cu2+/Cu1+ was caused by double effects through divalent metal ions (Fe2+) doping and excess oxygen (O2−δ) in CuAlO2. The maximum carrier concentration of 8.09 × 1017 cm−3 was obtained for the CuAlO2 sample at Fe content of 10 at.%.
•XPS and XAS are used to identify CuAl1−xFexO2 for understanding in-depth mechanism.•Fe doping improves interstitial O2 and surface oxygen adsorption capability of CuAlO2.•The variations of carrier concentration caused by double effects, Fe2+ and O2+δ
An integrated 100 V bootstrap diode (DBST) with anode engineering based on the double epitaxial process for enhancement mode gallium nitride (eGaN) transistor gate drivers is first proposed in this ...Letter. On the anode side, the P + dynamic field limiting ring (PDFLR) and the floating metal electrode (FME) are employed. The PDFLR can greatly suppress the peak electric field on both sides of the device during the reverse recovery period, which leads to a significant improvement in reverse recovery robustness. The FME lowers the anode injection efficiency in on-state and increases the hole recombination rate during reverse recovery, therefore, a fast reverse recovery is realised. The partial heavy doped N-type buried layer not only reduces the resistance of the drift region but also shortens the hole extraction path from the drift region to sub-electrode, as a result, reverse recovery tail current can be greatly shortened. Experiments combined with simulations show that the reverse recovery robustness of the optimised proposed DBST is improved by more than 12 times. Furthermore, the reverse recovery charge (Qrr) of the proposed structure is only 3.2 nC, which is 22% lower than that of the conventional device at the same forward current (IF) of 0.1 A.
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