Gallium oxide （Ga203） films were deposited on singlecrystalline sapphire （0001） substrate by radio frequency （RF） magnetron sputtering technique in the temperature range of 300--500 ℃. The microstructure of the...Gallium oxide （Ga203） films were deposited on singlecrystalline sapphire （0001） substrate by radio frequency （RF） magnetron sputtering technique in the temperature range of 300--500 ℃. The microstructure of the fl-Ga203 films were investigated in detail using X-ray diffractometer （XRD） and scanning electron microscope （SEM）. The results show that the film prepared at 500℃ exhibits the best crystallinity with a monoclinic structure （fl-Ga203）. Structure analysis reveals a clear out-of-plane orientation offl-Ga203 （201） II A1203 （0001）. The average transmittance of these films in the visible wavelength range exceeds 90%, and the optical band gap of the films varies from 4.68 eV to 4.94 eV which were measured by an ultraviolet-visible-near infrared （UV-vis-NIR） spectrophotometer. Therefore, it is hopeful that the fl-Ga203 film can be used in the UV optoelectronic devices.展开更多
We report a general method to graft aromatic molecules onto graphene thin film electrodes through a simple immersion process. Large-area electroactive graphene thin films grafted with methylene blue （MB） have been d...We report a general method to graft aromatic molecules onto graphene thin film electrodes through a simple immersion process. Large-area electroactive graphene thin films grafted with methylene blue （MB） have been developed as electrocatalytic electrodes for the oxidation of β-nicotinamide adenine dinucleotide （NADH）. The oxidation of NADH starts from -0.08 V （vs. Ag/AgC1） at the graphene-MB thin film electrodes, showing a decrease of 530 mV in overpotential compared to a Ti metal electrode. The graphene-MB thin films have promising applications in biosensors and biofuel cells due to their ability to promote NADH electron transfer reaction.展开更多
Nonpolar a-plane （1120） GaN films have been grown on r-plane （1102） sapphire by metal-organic chemical vapor deposition （MOCVD） under different growth pressures. The as-grown films are investigated by optical mi...Nonpolar a-plane （1120） GaN films have been grown on r-plane （1102） sapphire by metal-organic chemical vapor deposition （MOCVD） under different growth pressures. The as-grown films are investigated by optical microscopy, high-resolution X-ray diffraction （HRXRD） and Raman scattering. As growth pressure rises from 100 mbar to 400 mbar, the surface gets rougher, and the in-plane XRD full width at half maximum （FWHM） along the c-axis [0001] increases while that along the m-axis [1100] decreases. Meanwhile, residential stresses are reduced along both the c-axis and the m-axis. The structural anisotropy feature under 400 mbar is inverted with respect to 100 mbar, and the weakened anisotropy is achieved under a moderate pressure of 200 mbar, probably due to the suppressed Ga atomic migration along the c-axis under a larger pressure. We propose that pressure can affect a-plane growth through the V/III ratio.展开更多
Indium oxide(In_2O_3) films were prepared on Al_2O_3(0001) substrates at 700 °C by metal-organic chemical vapor deposition(MOCVD).Then the samples were annealed at 800 °C,900 °C and 1 000 °C,respec...Indium oxide(In_2O_3) films were prepared on Al_2O_3(0001) substrates at 700 °C by metal-organic chemical vapor deposition(MOCVD).Then the samples were annealed at 800 °C,900 °C and 1 000 °C,respectively.The X-ray diffraction(XRD) analysis reveals that the samples were polycrystalline films before and after annealing treatment.Triangle or quadrangle grains can be observed,and the corner angle of the grains becomes smooth after annealing.The highest Hall mobility is obtained for the sample annealed at 900 °C with the value about 24.74 cm^2·V^(-1)·s^(-1).The average transmittance for the films in the visible range is over 90%.The optical band gaps of the samples are about 3.73 e V,3.71 e V,3.70 eV and 3.69 eV corresponding to the In_2O_3 films deposited at 700 °C and annealed at 800 °C,900 °C and 1 000 °C,respectively.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61274113,61404091,61505144,51502203 and 51502204)the Opening Fund of Key Laboratory of Silicon Device Technology in Chinese Academy of Sciencesthe Tianjin Natural Science Foundation(Nos.14JCZDJC31500 and 14JCQNJC00800)
文摘Gallium oxide （Ga203） films were deposited on singlecrystalline sapphire （0001） substrate by radio frequency （RF） magnetron sputtering technique in the temperature range of 300--500 ℃. The microstructure of the fl-Ga203 films were investigated in detail using X-ray diffractometer （XRD） and scanning electron microscope （SEM）. The results show that the film prepared at 500℃ exhibits the best crystallinity with a monoclinic structure （fl-Ga203）. Structure analysis reveals a clear out-of-plane orientation offl-Ga203 （201） II A1203 （0001）. The average transmittance of these films in the visible wavelength range exceeds 90%, and the optical band gap of the films varies from 4.68 eV to 4.94 eV which were measured by an ultraviolet-visible-near infrared （UV-vis-NIR） spectrophotometer. Therefore, it is hopeful that the fl-Ga203 film can be used in the UV optoelectronic devices.
文摘We report a general method to graft aromatic molecules onto graphene thin film electrodes through a simple immersion process. Large-area electroactive graphene thin films grafted with methylene blue （MB） have been developed as electrocatalytic electrodes for the oxidation of β-nicotinamide adenine dinucleotide （NADH）. The oxidation of NADH starts from -0.08 V （vs. Ag/AgC1） at the graphene-MB thin film electrodes, showing a decrease of 530 mV in overpotential compared to a Ti metal electrode. The graphene-MB thin films have promising applications in biosensors and biofuel cells due to their ability to promote NADH electron transfer reaction.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60890192 and 50872146)
文摘Nonpolar a-plane （1120） GaN films have been grown on r-plane （1102） sapphire by metal-organic chemical vapor deposition （MOCVD） under different growth pressures. The as-grown films are investigated by optical microscopy, high-resolution X-ray diffraction （HRXRD） and Raman scattering. As growth pressure rises from 100 mbar to 400 mbar, the surface gets rougher, and the in-plane XRD full width at half maximum （FWHM） along the c-axis [0001] increases while that along the m-axis [1100] decreases. Meanwhile, residential stresses are reduced along both the c-axis and the m-axis. The structural anisotropy feature under 400 mbar is inverted with respect to 100 mbar, and the weakened anisotropy is achieved under a moderate pressure of 200 mbar, probably due to the suppressed Ga atomic migration along the c-axis under a larger pressure. We propose that pressure can affect a-plane growth through the V/III ratio.
基金supported by the National Natural Science Foundation of China(Nos.6127411311204212 and 61404091)+5 种基金the Program for New Century Excellent Talents in University(No.NCET-11-1064)the Tianjin Natural Science Foundation(Nos.13JCYBJC1570013JCZDJC2610014JCZDJC31500 and 14JCQNJC00800)the Tianjin Science and Technology Developmental Funds of Universities and Colleges(Nos.2010070320130701 and 20130702)
文摘Indium oxide(In_2O_3) films were prepared on Al_2O_3(0001) substrates at 700 °C by metal-organic chemical vapor deposition(MOCVD).Then the samples were annealed at 800 °C,900 °C and 1 000 °C,respectively.The X-ray diffraction(XRD) analysis reveals that the samples were polycrystalline films before and after annealing treatment.Triangle or quadrangle grains can be observed,and the corner angle of the grains becomes smooth after annealing.The highest Hall mobility is obtained for the sample annealed at 900 °C with the value about 24.74 cm^2·V^(-1)·s^(-1).The average transmittance for the films in the visible range is over 90%.The optical band gaps of the samples are about 3.73 e V,3.71 e V,3.70 eV and 3.69 eV corresponding to the In_2O_3 films deposited at 700 °C and annealed at 800 °C,900 °C and 1 000 °C,respectively.
