A figure of merit （FOM） Z = Up/τr, where Up is thepeak voltage, and τr is the rise time of the laser-induced thermoelectric voltage （LITV） signal, is defined for photodetector based on the LITV and the influence...A figure of merit （FOM） Z = Up/τr, where Up is thepeak voltage, and τr is the rise time of the laser-induced thermoelectric voltage （LITV） signal, is defined for photodetector based on the LITV and the influence of the parameters on FOM is analysed based on the time dependence of LITVs in La1-xCaxMnO3 （LCMO） and YBa2Cu3O7-σ （YBCO） thin films grown on vicinal-cut substrates. We find that the FOM increases as the photon penetration depth decreases, and linearly increases with the thermal diffusion constant D. To achieve the highest FOM, the film thickness d has to be controlled to an optimum value. We also find that the FOM is directly proportional to the laser absorption coefficient no, the laser energy density per pulse E, the illuminated length of film 1, sin（2α） [αis the vicinal-cut angle], the Seebeck coefficient anisotropy （ Sab - Sc）, and is inversely proportional to the mass density ρ and the specific heat c0.展开更多
Giant negative temperature coefficient of resistance （TCR） was observed in ZnO/Si （111） thin films. The films were grown using the pulsed laser deposition （PLD） technique, taking Si （111） wafer as substrates, ...Giant negative temperature coefficient of resistance （TCR） was observed in ZnO/Si （111） thin films. The films were grown using the pulsed laser deposition （PLD） technique, taking Si （111） wafer as substrates, with a substrate at the temperature below 450°C in the PLD. It is found that both TCR-temperature behavior and TCR value are strongly affected by deposition temperature. The maximal TCR value over -10.9%K-1 can be observed at the deposition temperature from 20°C to 350°C and reaches to -13%K-1 at deposition temperature 20°C where the film shows X-ray diffraction amorphous. The results suggest that the ZnO/Si films demonstrate great potentials when used in a low-cost, high-performance, non-cooling and highly sensitive bolometer.展开更多
In this paper,we briefly report the property diference of La_(1-x)Sr_(x)MnO_(3)(x=0.1)ultra—thin films(^([001])orientation)at diferent thickness grown on SrTiO_(3)(100)substrate.It is found that the magnetic interact...In this paper,we briefly report the property diference of La_(1-x)Sr_(x)MnO_(3)(x=0.1)ultra—thin films(^([001])orientation)at diferent thickness grown on SrTiO_(3)(100)substrate.It is found that the magnetic interaction is greatly enhanced when film thickness is between 5nm-10nm.展开更多
Both tensile strain and compressive strain effects on the properties of La_(1-x)Sr_(x)MnO_(3)(x=0.1)films were investigated.The films on SrTiO_(3)(100)display’unusual’tensile strain⋯。which supports a ferro-magnetic...Both tensile strain and compressive strain effects on the properties of La_(1-x)Sr_(x)MnO_(3)(x=0.1)films were investigated.The films on SrTiO_(3)(100)display’unusual’tensile strain⋯。which supports a ferro-magnetic metallic behavior when film thickness is larger than lOnm.The films on NdGaO_(3)(100)presenting compressive strain,on the other hand,demonstrate strongly enhanced insulating behavior.展开更多
A novel method to produce quantum dots on Si substrate using AAO template and UV pulsed laser deposition technique was proposed and tested.AAO template fabricated by two-step method was put in front of si single cryst...A novel method to produce quantum dots on Si substrate using AAO template and UV pulsed laser deposition technique was proposed and tested.AAO template fabricated by two-step method was put in front of si single crystal substrate.The luminescence target material La_(0.95)Eu_(0.05)BaB_(9)O_(16)was ablated by pulsed UV laser(248nm),and passed through the holes in AAO template,and was deposited on the substrate.Both Raman and luminescence spectra were measured to find the difference between the bulk target and the dots materials.展开更多
This paper reports that the transverse laser induced thermoelectric voltages （LITV） axe observed for the first time in the step flow growth （1- x）PD（Mg1/3Nb2/3）O3-xPbTiO3 （PMN-PT, x = 0.20, 0.33, 0.50） thin fi...This paper reports that the transverse laser induced thermoelectric voltages （LITV） axe observed for the first time in the step flow growth （1- x）PD（Mg1/3Nb2/3）O3-xPbTiO3 （PMN-PT, x = 0.20, 0.33, 0.50） thin films deposited on vicinal-cut strontium titanate single crystal substrates. Because lead magnesium niobate-lead titanate is a solid solution of lead magnesium niobate （PMN） and lead titanate （PT）, there are two types of signals. One is wide with a time response of a microsecond, and the other superimposed with the wide signal is narrow with a time response of a nanosecond. The transverse LITV signals depend on the ratio of PMN to PT drastically. Under the irradiation of 28-ns pulsed KrF excimer laser with the 248-nm wavelength, the largest induced voltage is observed in the 0.50Pb（Mg1/3Nb2/3）O3-0.50 PbTiO3 films. Moreover, the effects of film thickness, substrates, and tilt angles of substrates are also investigated.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 10274026, and a 2000/2001 Direct Grant under Project Code 2060204 of The Chinese University of Hong Kong.
文摘A figure of merit （FOM） Z = Up/τr, where Up is thepeak voltage, and τr is the rise time of the laser-induced thermoelectric voltage （LITV） signal, is defined for photodetector based on the LITV and the influence of the parameters on FOM is analysed based on the time dependence of LITVs in La1-xCaxMnO3 （LCMO） and YBa2Cu3O7-σ （YBCO） thin films grown on vicinal-cut substrates. We find that the FOM increases as the photon penetration depth decreases, and linearly increases with the thermal diffusion constant D. To achieve the highest FOM, the film thickness d has to be controlled to an optimum value. We also find that the FOM is directly proportional to the laser absorption coefficient no, the laser energy density per pulse E, the illuminated length of film 1, sin（2α） [αis the vicinal-cut angle], the Seebeck coefficient anisotropy （ Sab - Sc）, and is inversely proportional to the mass density ρ and the specific heat c0.
文摘Giant negative temperature coefficient of resistance （TCR） was observed in ZnO/Si （111） thin films. The films were grown using the pulsed laser deposition （PLD） technique, taking Si （111） wafer as substrates, with a substrate at the temperature below 450°C in the PLD. It is found that both TCR-temperature behavior and TCR value are strongly affected by deposition temperature. The maximal TCR value over -10.9%K-1 can be observed at the deposition temperature from 20°C to 350°C and reaches to -13%K-1 at deposition temperature 20°C where the film shows X-ray diffraction amorphous. The results suggest that the ZnO/Si films demonstrate great potentials when used in a low-cost, high-performance, non-cooling and highly sensitive bolometer.
基金This work is supported by National Natural Science Foundation of China under contract number of 10274026Yunnan Natural Science Fondation of China under contract number of 2003E0019M
文摘In this paper,we briefly report the property diference of La_(1-x)Sr_(x)MnO_(3)(x=0.1)ultra—thin films(^([001])orientation)at diferent thickness grown on SrTiO_(3)(100)substrate.It is found that the magnetic interaction is greatly enhanced when film thickness is between 5nm-10nm.
基金This work is supported by National Natural Science Foundation of China under contract number of 10274026Yunnan Natural Science Foundation of China under contract number of 2003E0019M
文摘Both tensile strain and compressive strain effects on the properties of La_(1-x)Sr_(x)MnO_(3)(x=0.1)films were investigated.The films on SrTiO_(3)(100)display’unusual’tensile strain⋯。which supports a ferro-magnetic metallic behavior when film thickness is larger than lOnm.The films on NdGaO_(3)(100)presenting compressive strain,on the other hand,demonstrate strongly enhanced insulating behavior.
文摘A novel method to produce quantum dots on Si substrate using AAO template and UV pulsed laser deposition technique was proposed and tested.AAO template fabricated by two-step method was put in front of si single crystal substrate.The luminescence target material La_(0.95)Eu_(0.05)BaB_(9)O_(16)was ablated by pulsed UV laser(248nm),and passed through the holes in AAO template,and was deposited on the substrate.Both Raman and luminescence spectra were measured to find the difference between the bulk target and the dots materials.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10274026)
文摘This paper reports that the transverse laser induced thermoelectric voltages （LITV） axe observed for the first time in the step flow growth （1- x）PD（Mg1/3Nb2/3）O3-xPbTiO3 （PMN-PT, x = 0.20, 0.33, 0.50） thin films deposited on vicinal-cut strontium titanate single crystal substrates. Because lead magnesium niobate-lead titanate is a solid solution of lead magnesium niobate （PMN） and lead titanate （PT）, there are two types of signals. One is wide with a time response of a microsecond, and the other superimposed with the wide signal is narrow with a time response of a nanosecond. The transverse LITV signals depend on the ratio of PMN to PT drastically. Under the irradiation of 28-ns pulsed KrF excimer laser with the 248-nm wavelength, the largest induced voltage is observed in the 0.50Pb（Mg1/3Nb2/3）O3-0.50 PbTiO3 films. Moreover, the effects of film thickness, substrates, and tilt angles of substrates are also investigated.
