RESUMO
Self-powered solar-blind photodetectors (PDs) are promising for military and civilian applications owing to convenient operation, easy preparation, and weak-light sensitivity. In the present study, the solar-blind deep-ultraviolet (DUV) photodetector based on amorphous Ga2O3 (a-Ga2O3) and with a simple vertical stack structure is proposed by applying the low-cost magnetron sputtering technology. By tuning the thickness of the amorphous Ga2O3 layer, the device exhibits excellent detection performance. Under 3â V reverse bias, the photodetector achieves a high responsivity of 671A/W, a high detectivity of 2.21 × 1015 Jones, and a fast response time of 27/11â ms. More extraordinary, with the help of the built-in electric field at the interface, the device achieves an excellent performance in detection when self-powered, with an ultrahigh responsivity of 3.69 A/W and a fast response time of 2.6/6.6â ms under 254â nm light illumination. These results demonstrate its superior performance to most of the self-powered Schottky junction UV photodetectors reported to date. Finally, the Pt/a-Ga2O3/ITO Schottky junction photodiode detector is verified as a good performer in imaging, indicating its applicability in such fields as artificial intelligence, machine vision, and solar-blind imaging.
RESUMO
One of the most important applications of photodetectors is as sensing units in imaging systems. In practical applications, a photodetector array with high uniformity and high performance is an indispensable part of the imaging system. Herein, a photodetector array (5 × 4) consisting of 20 photodetector units, in which the photosensitive layer involves preprocessing commercial ε-Ga2O3 films with high temperature annealing, have been constructed by low-cost magnetron sputtering and mask processes. The ε-Ga2O3 ultraviolet photodetector unit shows excellent responsivity and detectivity of 6.18 A/W and 5 × 1013 Jones, respectively, an ultra-high light-to-dark ratio of 1.45 × 105, and a fast photoresponse speed (0.14/0.09 s). At the same time, the device also shows good solar-blind characteristics and stability. Based on this, we demonstrate an ε-Ga2O3-thin-film-based solar-blind ultraviolet detector array with high uniformity and high performance for solar-blind imaging in optoelectronic integration applications.
RESUMO
The construction of heterojunctions has attracted considerable attention among the various strategies of water-splitting for hydrogen evolution due to their band structure advantages. In this research, we combined chemical vapor deposition and pulsed laser deposition to fabricate MoS2/g-C3N4 heterojunction films on indium-tin oxide glass substrates, and we studied the photoelectrochemical (PEC) performance. The x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and scanning electron microscope characterizations suggested the successful preparation of MoS2/g-C3N4 heterojunction films. In particular, the shifts of the peak positions in the XPS spectra indicated the formation of a strong interaction between the g-C3N4 and MoS2 films. After depositing MoS2 on the g-C3N4 film, the visible-light absorption was enhanced and broadened, the electrical conductivity improved, and the intensity of the photoluminescence peak decreased. As a result, the greater generation, faster transport, and lower recombination rate of electrons and holes caused the heterojunction films to show higher PEC performance. More importantly, the obtained MoS2/g-C3N4 film was confirmed to be an n-n type heterojunction and to have a typical type-II band structure, which could indeed suppress the recombination and promote the separation, transfer, and transport of photogenerated electron-holes. Finally, the obtained MoS2/g-C3N4 film successfully achieved the overall water-splitting and the H2 evolution rate when the visible-light radiation reached 252 µmol/h.
RESUMO
With applications in high performance electronics, photovoltaics, and catalysis, two-dimensional (2D) transition metal dichalcogenides (TMDCs) attract extensive attention due to their extraordinary physical properties. People have focused on TMDC-based materials for years, while the low mobility greatly hinders their further application. TMDC-based heterostructures with tunable band alignment have been experimentally confirmed to be feasible for photoelectronic devices or photocatalysts. Based on the density functional theory (DFT), there are four discoveries in this work: (1) we propose two new heterostructures based on BSe and MoS2/WS2 that have quite low mismatches and intrinsic type-II alignments. (2) Even though the VBM of BSe-MoS2 are completely contributed by BSe, the heterostructure is still endowed with a lower effective mass and a better transport characteristic in comparison with pristine structures. (3) A promoted absorption ability and a better transport characteristic oppose each other and the two characteristics cannot be obtained at the same time. (4) Tension strained structures can induce promoted light absorption in the solar spectrum and the predicted efficiency of the BSe-MoS2 bilayer can be as high as â¼19.3%, when the external electric field is applied. This theoretical survey proves that BSe-MoS2/WS2 with high flexibility and tunability are potential candidates for novel electronic devices and photocatalysts.
RESUMO
The limited operating temperature is the main obstacle for the practical applications of magnetic refrigeration. In this work, the voltage control of magnetocaloric effect (MCE) is investigated in a La0.7Sr0.3MnO3 (LSMO)/CeO2/Pt device. Different from the conventional method of volatile manipulating MCE by large-voltage-induced strain, nonvolatile manipulation of magnetocaloric operating temperature with good stability is realized in the LSMO film by applying low voltages of less than 2.3 V. The experimental results demonstrate that the magnetic entropy change peak temperature for the LSMO film can be extended from 302 to 312 K by voltage. This nonvolatile effect can be well-understood with the resistive switching mechanism and has potential in promoting microscale refrigeration technology.
RESUMO
We demonstrate a memory device with multifield switchable multilevel states at room temperature based on the integration of straintronics and spintronics in a La2/3Ba1/3MnO3/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) (011) heterostructure. By precisely controlling the electric field applied on the PMN-PT substrate, multiple nonvolatile resistance states can be generated in La2/3Ba1/3MnO3 films, which can be ascribed to the strain-modulated metal-insulator transition and phase separation of Manganite. Furthermore, because of the strong coupling between spin and charge degrees of freedom, the resistance of the La2/3Ba1/3MnO3 film can be readily modulated by magnetic field over a broad temperature range. Therefore, by combining electroresistance and magnetoresistance effects, multilevel resistance states with excellent retention and endurance properties can be achieved at room temperature with the coactions of electric and magnetic fields. The incorporation of ferroelastic strain and magnetic and resistive properties in memory cells suggests a promising approach for multistate, high-density, and low-power consumption electronic memory devices.
RESUMO
The annual reports of human-cattle synchronous chemotherapy from 1992 to 2008 were collected and analyzed, and its effect on schistosomiasis control was evaluated. The results showed that human and cattle infection rates decreased by 72.37% (chi2 = 9.85, P < 0.01) and 65.18% (chi2 = 5.63, P < 0.01), respectively. The snail infection rate and the density of infected snail decreased by 63.64% and 69.44%, respectively. It is concluded that schistosomiasis in Qianjiang City has been effectively controlled after the implementation of human-cattle synchronous chemotherapy for 16 years.
