Vanadium dioxide(VO_(2))is a strongly correlated material,and it has become known due to its sharp metal-insulator transition(MIT)near room temperature.Understanding the thermal properties and their change across MIT ...Vanadium dioxide(VO_(2))is a strongly correlated material,and it has become known due to its sharp metal-insulator transition(MIT)near room temperature.Understanding the thermal properties and their change across MIT of VO_(2)thin film is important for the applications of this material in various devices.Here,the changes in thermal conductivity of epitaxial and polycrystalline VO_(2)thin film across MIT are probed by the time-domain thermoreflectance(TDTR)method.The measurements are performed in a direct way devoid of deposition of any metal thermoreflectance layer on the VO_(2)film to attenuate the impact from extra thermal interfaces.It is demonstrated that the method is feasible for the VO_(2)films with thickness values larger than 100 nm and beyond the phase transition region.The observed reasonable thermal conductivity change rates across MIT of VO_(2)thin films with different crystal qualities are found to be correlated with the electrical conductivity change rate,which is different from the reported behavior of single crystal VO_(2)nanowires.The recovery of the relationship between thermal conductivity and electrical conductivity in VO_(2)film may be attributed to the increasing elastic electron scattering weight,caused by the defects in the film.This work demonstrates the possibility and limitation of investigating the thermal properties of VO_(2)thin films by the TDTR method without depositing any metal thermoreflectance layer.展开更多
Cerium dioxide, CeO2, is a potentially superior material in a myriad of areas, and many methods have been proposed to deposit single crystal CeO2 thin films. A novel fabrication technique utilizing dual plasma generat...Cerium dioxide, CeO2, is a potentially superior material in a myriad of areas, and many methods have been proposed to deposit single crystal CeO2 thin films. A novel fabrication technique utilizing dual plasma generated by metal vacuum arc (MEVVA) and radio frequency (RF) is discussed in this paper. We have recently conducted a systematic investigation to determine the optimal process window to deposit CeO2 thin films’on Si(100) substrates. The X-ray diffraction results show the existence of CeO2(100) in the as-deposited sample.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61825102,51872038,and 52021001)the“111”Project,China(Grant No.B18011).
文摘Vanadium dioxide(VO_(2))is a strongly correlated material,and it has become known due to its sharp metal-insulator transition(MIT)near room temperature.Understanding the thermal properties and their change across MIT of VO_(2)thin film is important for the applications of this material in various devices.Here,the changes in thermal conductivity of epitaxial and polycrystalline VO_(2)thin film across MIT are probed by the time-domain thermoreflectance(TDTR)method.The measurements are performed in a direct way devoid of deposition of any metal thermoreflectance layer on the VO_(2)film to attenuate the impact from extra thermal interfaces.It is demonstrated that the method is feasible for the VO_(2)films with thickness values larger than 100 nm and beyond the phase transition region.The observed reasonable thermal conductivity change rates across MIT of VO_(2)thin films with different crystal qualities are found to be correlated with the electrical conductivity change rate,which is different from the reported behavior of single crystal VO_(2)nanowires.The recovery of the relationship between thermal conductivity and electrical conductivity in VO_(2)film may be attributed to the increasing elastic electron scattering weight,caused by the defects in the film.This work demonstrates the possibility and limitation of investigating the thermal properties of VO_(2)thin films by the TDTR method without depositing any metal thermoreflectance layer.
基金The work was supported by Hong Kong RGC CERG9040344 and 9040412, RGC / Germany Joint Schemes9050084 and 9050150, and CityU S
文摘Cerium dioxide, CeO2, is a potentially superior material in a myriad of areas, and many methods have been proposed to deposit single crystal CeO2 thin films. A novel fabrication technique utilizing dual plasma generated by metal vacuum arc (MEVVA) and radio frequency (RF) is discussed in this paper. We have recently conducted a systematic investigation to determine the optimal process window to deposit CeO2 thin films’on Si(100) substrates. The X-ray diffraction results show the existence of CeO2(100) in the as-deposited sample.
