Self-powered deep ultraviolet photodetectors (DUV PDs) are essential in environmental monitoring, flame detection, missile guidance, aerospace, and other fields. A heterojunction photodetector based on p-CuI/n-ZnGa 2 O 4 has been fabricated by pulsed laser deposition combined with vacuum thermal evaporation. Under 260 nm DUV light irradiation, the photodetector exhibits apparent self-powered performance with a maximum responsivity and specific detectivity of 2.75 mA/W and 1.10 × 10 11 Jones at 0 V. The photodetector exhibits high repeatability and stability under 260 nm periodic illumination. The response and recovery time are 205 ms and 133 ms, respectively. This work provides an effective strategy for fabricating high-performance self-powered DUV photodetectors.
Zinc gallium oxide (ZnGa 2 O 4 ) has attracted considerable interest in deep-ultraviolet photodetectors, due to the ultrawide bandgap, high transmittance in the ultraviolet (UV) region, and excellent environmental stability. In this study, ZnGa 2 O 4 thin films were deposited on p-GaN epi-layers using pulsed laser deposition, resulting in improved crystalline quality. The ZnGa 2 O 4 film exhibited a bandgap of 4.93 eV, calculated through absorption spectra. A heterojunction photodetector (PD) was constructed, demonstrating a rectification effect, an on/off ratio of 12,697 at −5.87 V, a peak responsivity of 14.5 mA/W, and a peak detectivity of 1.14 × 10 12 Jones (262 nm, −6 V). The PD exhibited a fast response time (39 ms) and recovery time (30 ms) under 262 nm illumination. The band diagram based on the Anderson model elucidates the photoresponse and carrier transport mechanism. This work paves the way for advancing next-generation optoelectronics.
The effect of light intensity and temperature on the performance of InGaN solar cells were investigated experimentally. With the increase of light intensity, the short circuit current density (J sc ) increases linearly and the open circuit voltage (V oc ) increases logarithmically. The filling factor (FF) and relative efficiency (η), however, increase first and then decrease which is explained by the loss coming from the electrical series resistance under higher light intensity. With the increase of temperature, on the other hand, the performance of the solar cell becomes worse. This paper provides useful information concerning the reliability of GaN-based solar cells.
Today's technology is tuned towards faster, smaller and better efficiency. This trend has resulted in tremendous heat being generated in microelectronics components and if not properly managed, it can result in failure of microelectronics components. A critical issue is the removal of this heat generated. We report here a new type of nano thermal interface material (Nano-TIM) using the electrospinning process with nano silver particle as thermal enhancement filler. With the electrospinning process, polymer nanofibers are formed in nano scale in diameters. The morphology of the nanofibers is of optimum importance and scanning electron microscopy (SEM) was used to analyze it. The characterization of the nanofibers was carried out using thermo-gravimetric analyzers (TGA) and differential scanning calorimeter (DSC) to determining the degradation and melting temperature of the nanofibers. The mechanical property was analyzed using an Instron micro-functional mechanical tester. The work shows that nano-TIM with nano silver particles has significant potentials to replace conventional thermal pad materials.
Polymer-derived ceramic (PDC) is considered an excellent sensing material for harsh environments such as aero-engines and nuclear reactors. However, there are many inherent limitations not only in pure PDC but also in its common fabrication method by furnace thermolysis. Therefore, this study proposes a novel method of rapid in situ fabrication of PDC composite thin-film sensors by laser pyrolysis. Using this method with different fillers, a sensitive PDC composite film layer with high-quality graphite can be obtained quickly, which is more flexible and efficient compared to the traditional furnace thermolysis. Furthermore, this study analyzes the reaction differences between laser pyrolysis and furnace thermolysis. The laser pyrolysis method principally produces β-SiC and enhances the graphitization of amorphous carbon, while the degree of graphitization by furnace thermolysis is low. In addition, it is capable of rapidly preparing an insulating PDC composite film, which still has a resistance of 5 MΩ at 600 °C. As a proof of this method, the PDC composite thin-film strain sensors are fabricated in situ on nickel alloys and aluminum oxide substrates, respectively. The sensor fabricated on the nickel alloy with a high gauge factor of over 100 can be used in high-temperature environments below 350 °C without the protection of an oxidation-resistant coating. In this way, the approach pioneers the in situ laser fabrication of functional PDC films for sensors, and it has great potential for the in situ sensing of complex curved surfaces in harsh environments.
Efficient electron transfer and excellent CO2 adsorption capacity are of great significance for improving CO2 photoreduction efficiency. 3D-0D ZnO/CsPbBr3 S-scheme heterojunction hollow spheres were successfully prepared via a simple self-assembled process for efficient CO2 photoreduction. Photocatalytic CO2 reduction experiments showed that the ZnO/CsPbBr3 had the excellent CO2 catalytic conversion activity to CO, which was about 2.61 times higher than that of ZnO hollow micro-spheres and 1.9 times higher than that of CsPbBr3 quantum dots. Photoelectrochemical characterization confirmed that the ZnO/CsPbBr3 composite had good photoelectric conversion ability and carrier transfer ability, which was beneficial to the photocatalytic reaction. The suitable band gap structure and DFT calculation results showed that the formation of built-in electric field in the heterojunction of ZnO/CsPbBr3 can greatly improve the S-scheme electron transfer ability, which can foster the CO2 photoreduction. Besides, the introduction of 3D structure improved the dispersion of CsPbBr3 QDs and effectively enhanced the ability of the catalyst to capture CO2, which greatly promoted the CO2 photoreduction reaction. The current work can present a novel S-scheme photocatalyst, which is looked forward to providing a certain perception into the advance of novel highly efficient CsPbBr3 QDs-based photocatalysts for CO2 resource utilization.
β-Ga2O3 photodetectors have the advantages of low dark current and strong radiation resistance in UV detection. However, the limited photocurrent has restricted their applications. Herein, MSM UV photodetectors based on (InxGa1−x)2O3 (x = 0, 0.1, 0.2, 0.3) by a sol-gel method were fabricated and studied. The doping of indium ions in Ga2O3 leads to lattice distortion and promotes the formation of oxygen vacancies. The oxygen vacancies in (InxGa1−x)2O3 can be modulated by various proportions of indium, and the increased oxygen vacancies contribute to the enhancement of electron concentration. The results show that the amorphous In0.4Ga1.6O3 photodetector exhibited improved performances, including a high light-to-dark current ratio (2.8 × 103) and high responsivity (739.2 A/W). This work provides a promising semiconductor material In0.4Ga1.6O3 for high-performance MSM UV photodetectors.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
