Currently, Nanjing South Railway Station planning to implement slate roof renovation is integrating solar cell modules into traditional roof materials to generate clean energy. Copper–indium–gallium diselenide(CuIn1-xGaxSe2, CIGS) is one of the most promising materials for thin film solar cells. Cu(In1-xGax)Se2films were deposited by a one-step radio frequency magnetron sputtering process at low substrate temperature. X-ray diffraction, Raman, scanning electron microscopy, energydispersive X-ray spectroscopy, and electrical and optical measurements were carried out to investigate the deposited films. The results reveal that a temperature of 320 °C is critical for near-stoichiometric CIGS films with uniform surface morphology. Cu-rich phase particulates are found at less than this temperature. The sample deposited at380 °C gives well-crystalline single-phase CIGS film.Furthermore, the electrical and optical performances of the absorber layer are improved significantly with the increasing substrate temperature.
Perovskite-based materials can be widely used in the aerospace and transportation field. Perovskite manganese oxides La0.7Sr0.3MnO3(LSMO) thin films were grown on LaAlO3(100) and Si(100) single crystal substrates by the polymer-assisted chemical solution deposition(PACSD) method. Electronic transport behavior,microstructure, and magnetoresistance(MR) of LSMO thin films on different substrates were investigated. The resistance of LSMO films fabricated on LaAlO3substrates is smaller than that on the Si substrates. The magnetic field reduces resistance of LSMO films both on Si and LAO in the wide temperature region, when the insulator-metal transition temperature shifts to higher temperature. The low-field magnetoresistance of LSMO films on Si in low temperature range at 1 T is larger than that of LSMO films on LAO. However, the MR of LSMO film on LAO films at room-temperature is about 5.17 %. The thin films are smooth and dense with uniform nanocrystal size grain.These results demonstrate that PACSD is an effective technique for producing high quality LSMO films, which is significant to improve the magnetic properties and the application of automotive sensor.
Topological insulators are insulating in the bulk but have metallic surface states. Its unique physicochemical properties can find numerous applications in electronics, spintronics, photonics, the energy sciences, and the signal control of transportation. We report an experimental approach to synthesize the high-quality single crystal of topological insulator Bi2Te3by using self-flux method. We obtained the optimal preparation conditions by adjusting the parameters of heat treatment, and successfully prepared the single-crystal Bi2Te3sample. The as-grown samples have a surface with bright metallic luster and are soft and fragile. Furthermore, Bi2Te3has the obvious layer structure from SEM results. The data of X-ray diffraction and scanning electron microscope show that Bi2Te3single crystal grows along the c-axis with the order of Te(1)–Bi–Te(2)–Bi–Te(1)and crystallizes in the hexagonal system with space group of R/3 m. The q–T curve shows that q decreases with temperature, showing metallic behavior over the whole temperature range.
Magnetoresistive sensor can be widely used in modern transportation field, such as the vehicle positioning and navigation system, vehicle detection system, and intelligent transportation system. In order to improve the efficiency of magnetoresistive sensor, we synthesized La0.8Sr0.2MnO3polycrystalline bulks at different sintering temperatures and investigated their DC and AC transport properties in this work. As a result, all samples showed insulator–metal(I–M) phase transition, and the transition temperature(TI–M) shifted to higher temperature with the increase of sintering temperature. The TI–Mmeasured at different AC frequencies was smaller than that measured at DC condition, which implied that the I–M phase transition was suppressed at AC frequencies. The resistivity measured at high AC frequencies was larger than that measured at low AC frequencies, which could be attributed to the change of the magnetic penetration depth(d). However, the room-temperature AC-magnetoresistance(MR) at low frequencies was much larger than that at high frequencies and room-temperature DC-MR. These findings demonstrate that reducing the AC frequency is an effective way for enhancing the room-temperature MR, which can be used to promote the efficiency of magnetoresistive sensor.
