The n-type conductive BaNb_(0.3) Ti_(0.7)O_(3) thin films were grown on SrTiO_(3) (001) substrates by computer-controlled laser molecular beam epitaxy. The BaNb0.3Ti0.7O3 films with (001) orientation are epitaxially g...The n-type conductive BaNb_(0.3) Ti_(0.7)O_(3) thin films were grown on SrTiO_(3) (001) substrates by computer-controlled laser molecular beam epitaxy. The BaNb0.3Ti0.7O3 films with (001) orientation are epitaxially grown on SrTiO_(3) substrates, as confirmed by x-ray diffraction techniques. The root-mean-square surface roughness of the deposited thin films is measured to be 0.24 nm by atomic force microscopy. The resistivity, carrier concentration and mobility of the BaNb_(0.3)Ti_(0.7)O_(3) thin film are 5.9 × 10^(-4) Ω. cm, 1.8 × 10^(21)cm^(-3) and 10. 7cm^(2).V^(-1).s^(-1) at room temperature,respectively, which are the best values in Nb-doped BaTiO3 thin films reported so far to our knowledge.展开更多
We report the optical oscillations with monolayer periodicity observed by an oblique-incidence reflectance difference(OIRD)technique on the epitaxial growth of Nb-doped SrTiO_(3) on SrTiO_(3) substrate.The periodicity...We report the optical oscillations with monolayer periodicity observed by an oblique-incidence reflectance difference(OIRD)technique on the epitaxial growth of Nb-doped SrTiO_(3) on SrTiO_(3) substrate.The periodicity was verified by the simultaneously measured reflection high-energy electron diffraction intensity oscillations.The OIRD oscillation damps during deposition,but can recover after the growth is interrupted for some time.We interpret the optical oscillations as a result of the periodic changes of the surface morphologies due to the two-dimensional layer-by-layer growth of thin films.展开更多
Superconducting MgB_(2) thin films were fabricated on Al_(2)O_(3)(0001)substrates under an ex situ processing conditions.Boron thin films were deposited by pulsed laser deposition followed by a post-annealing process....Superconducting MgB_(2) thin films were fabricated on Al_(2)O_(3)(0001)substrates under an ex situ processing conditions.Boron thin films were deposited by pulsed laser deposition followed by a post-annealing process.Resistance measurements of the deposited MgB_(2) films show Tc of~39 K,while scanning electron microscopy and x-ray diffraction analysis indicate that the films consist of well-crystallized grains with a highly c-axis-oriented structure.展开更多
Rh-doped barium titanate (BaTiO3) epitaxial thin films have been fabricated on SrTiO_(3) (100) substrates by pulsed laser deposition. The nonlinear optical properties of the films were determined using the z-scan meth...Rh-doped barium titanate (BaTiO3) epitaxial thin films have been fabricated on SrTiO_(3) (100) substrates by pulsed laser deposition. The nonlinear optical properties of the films were determined using the z-scan method at a wavelength of 532nm with a laser duration of 10hs. The real and imaginary parts of the third-order nonlinear susceptibility χ^((3)) were 5.71 × 10^(-7) esu and 9.59×10^(-8) esu, respectively. The real part value of x(3) of the Rh:BaTiO3 films is about one order larger than that of Ce-doped BaTiO3 thin films. The results show that Rh:BaTiO3 thin films have great potential applications for nonlinear optical devices.展开更多
Atomically regulated unit-cell by unit-cell homoepitaxial SrTiO_(3) and heteroepitaxial BaTiO_(3) films were fabricated on SrTiO_(3)(100)substrates by laser molecular beam epitaxy.The fine streak patterns and more tha...Atomically regulated unit-cell by unit-cell homoepitaxial SrTiO_(3) and heteroepitaxial BaTiO_(3) films were fabricated on SrTiO_(3)(100)substrates by laser molecular beam epitaxy.The fine streak patterns and more than 1000 cycles undamping intensity oscillation were obtained by in situ reflection high-energy electron diffraction with precisely controlled intermittence between each unit-cell layer.The surface morphology of the films was examined by atomic force microscopy.The root-mean-square surface roughness of the films is about 0.1 nm.展开更多
A pyrometric absorption method suitable for strongly absorbing films has been developed to monitor the YBa_(2)Cu_(3)O_(7-δ)film growth.This method makes use of the temperature difference between the heater and the su...A pyrometric absorption method suitable for strongly absorbing films has been developed to monitor the YBa_(2)Cu_(3)O_(7-δ)film growth.This method makes use of the temperature difference between the heater and the substrate.By deducing the absorption formula of radiation light and fitting it to the radiation intensity data measured,it is possible to monitor the film thickness and the film surface temperature during deposition.Experimental results show that this is a simple and practicable method.展开更多
Laser molecular beam epitaxy(laser MBE)technique was utilized to grow the barium titanate(BaTiO_(3),BTO)thin films on SrTiO_(3)(100)substrates.The surface morphology of the BaTiO_(3) thin films was studied by atomic f...Laser molecular beam epitaxy(laser MBE)technique was utilized to grow the barium titanate(BaTiO_(3),BTO)thin films on SrTiO_(3)(100)substrates.The surface morphology of the BaTiO_(3) thin films was studied by atomic force microscopy(AFM).Two-and three-dimensional AFM images were obtained.The root mean square surface roughness,the height profile,the histogram and the bearing ratio of the height distributions for the BaTiO_(3) thin films were analyzed in detail.The results indicate that the laser MBE thin films exhibit an atomically smooth surface.展开更多
The polarization dependence of conduction inf ersubband transitions in GaAs/AlGaAs step multiqua.ntum well structures hasJbeen studied using infrared spectroscopy.For S-polarized 45°oblique angle incidence config...The polarization dependence of conduction inf ersubband transitions in GaAs/AlGaAs step multiqua.ntum well structures hasJbeen studied using infrared spectroscopy.For S-polarized 45°oblique angle incidence configuration with respect to sample surface normal,the transverse electric(TE)active intersubband transitions were observed.Both transverse electric and transverse magnetic(TM)active intersubband transitions were obtained in P-polarized incidence at 45°angle on sample,which shows a small energy splitting between TE and TM absorption peaks.展开更多
文摘The n-type conductive BaNb_(0.3) Ti_(0.7)O_(3) thin films were grown on SrTiO_(3) (001) substrates by computer-controlled laser molecular beam epitaxy. The BaNb0.3Ti0.7O3 films with (001) orientation are epitaxially grown on SrTiO_(3) substrates, as confirmed by x-ray diffraction techniques. The root-mean-square surface roughness of the deposited thin films is measured to be 0.24 nm by atomic force microscopy. The resistivity, carrier concentration and mobility of the BaNb_(0.3)Ti_(0.7)O_(3) thin film are 5.9 × 10^(-4) Ω. cm, 1.8 × 10^(21)cm^(-3) and 10. 7cm^(2).V^(-1).s^(-1) at room temperature,respectively, which are the best values in Nb-doped BaTiO3 thin films reported so far to our knowledge.
基金Supported by the National Natural Science Foundation of China under Grant No.60028404.
文摘We report the optical oscillations with monolayer periodicity observed by an oblique-incidence reflectance difference(OIRD)technique on the epitaxial growth of Nb-doped SrTiO_(3) on SrTiO_(3) substrate.The periodicity was verified by the simultaneously measured reflection high-energy electron diffraction intensity oscillations.The OIRD oscillation damps during deposition,but can recover after the growth is interrupted for some time.We interpret the optical oscillations as a result of the periodic changes of the surface morphologies due to the two-dimensional layer-by-layer growth of thin films.
基金Supported by a grant from the State Kay Program of China and the National Natural Science Foundation of China.
文摘Superconducting MgB_(2) thin films were fabricated on Al_(2)O_(3)(0001)substrates under an ex situ processing conditions.Boron thin films were deposited by pulsed laser deposition followed by a post-annealing process.Resistance measurements of the deposited MgB_(2) films show Tc of~39 K,while scanning electron microscopy and x-ray diffraction analysis indicate that the films consist of well-crystallized grains with a highly c-axis-oriented structure.
基金Supported by the National Natural Science Foundation of China under Grant No.5001161952。
文摘Rh-doped barium titanate (BaTiO3) epitaxial thin films have been fabricated on SrTiO_(3) (100) substrates by pulsed laser deposition. The nonlinear optical properties of the films were determined using the z-scan method at a wavelength of 532nm with a laser duration of 10hs. The real and imaginary parts of the third-order nonlinear susceptibility χ^((3)) were 5.71 × 10^(-7) esu and 9.59×10^(-8) esu, respectively. The real part value of x(3) of the Rh:BaTiO3 films is about one order larger than that of Ce-doped BaTiO3 thin films. The results show that Rh:BaTiO3 thin films have great potential applications for nonlinear optical devices.
基金Supported by the National Natural Science Foundation of China under Grant Nos.69437010 and 59392800the Chinese Academy of Sciencesthe National Centre for R&D on Superconductivity of China.
文摘Atomically regulated unit-cell by unit-cell homoepitaxial SrTiO_(3) and heteroepitaxial BaTiO_(3) films were fabricated on SrTiO_(3)(100)substrates by laser molecular beam epitaxy.The fine streak patterns and more than 1000 cycles undamping intensity oscillation were obtained by in situ reflection high-energy electron diffraction with precisely controlled intermittence between each unit-cell layer.The surface morphology of the films was examined by atomic force microscopy.The root-mean-square surface roughness of the films is about 0.1 nm.
基金Supported by the National Centre for Research and Development on Superconductor of China.
文摘A pyrometric absorption method suitable for strongly absorbing films has been developed to monitor the YBa_(2)Cu_(3)O_(7-δ)film growth.This method makes use of the temperature difference between the heater and the substrate.By deducing the absorption formula of radiation light and fitting it to the radiation intensity data measured,it is possible to monitor the film thickness and the film surface temperature during deposition.Experimental results show that this is a simple and practicable method.
基金Supported by the National Natural Science Foundation of China under Grant Nos.59392800 and 69437101the Chinese Academy of Sciences,the National Superconducting Research Center,and the Research Grant No.94-189 RG/PHYS/AS of the Third World Academy of Sciences.
文摘Laser molecular beam epitaxy(laser MBE)technique was utilized to grow the barium titanate(BaTiO_(3),BTO)thin films on SrTiO_(3)(100)substrates.The surface morphology of the BaTiO_(3) thin films was studied by atomic force microscopy(AFM).Two-and three-dimensional AFM images were obtained.The root mean square surface roughness,the height profile,the histogram and the bearing ratio of the height distributions for the BaTiO_(3) thin films were analyzed in detail.The results indicate that the laser MBE thin films exhibit an atomically smooth surface.
基金Supported by the National Natural Science Foundation of China.
文摘The polarization dependence of conduction inf ersubband transitions in GaAs/AlGaAs step multiqua.ntum well structures hasJbeen studied using infrared spectroscopy.For S-polarized 45°oblique angle incidence configuration with respect to sample surface normal,the transverse electric(TE)active intersubband transitions were observed.Both transverse electric and transverse magnetic(TM)active intersubband transitions were obtained in P-polarized incidence at 45°angle on sample,which shows a small energy splitting between TE and TM absorption peaks.
