Fine structure in the electron emission process for DX(Sn)centers in AlGaAs has been studied with high resolution Laplace defect spectroscopy.The influence of the different local configuration of Al and Ga atoms aroun...Fine structure in the electron emission process for DX(Sn)centers in AlGaAs has been studied with high resolution Laplace defect spectroscopy.The influence of the different local configuration of Al and Ga atoms around the centers on the electron thermal emissions was observed.An experimental evidence for the microscopic structure of two DX-like centers in Sn-doped AlGaAs is provided.展开更多
Undoped ZnO and doped ZnO films were deposited on the MgO（111） substrates using oxygen plasma-assisted molecular beam expitaxy. The orientations of the grown ZnO thin film were investigated by in situ reflection hig...Undoped ZnO and doped ZnO films were deposited on the MgO（111） substrates using oxygen plasma-assisted molecular beam expitaxy. The orientations of the grown ZnO thin film were investigated by in situ reflection high-energy electron diffraction and ex situ x-ray diffraction（XRD）. The film roughness was measured by atomic force microscopy, which was correlated with the grain sizes determined by XRD. Synchrotron-based x-ray absorption spectroscopy was performed to study the doping effect on the electronic properties of the ZnO films, compared with density functional theory calculations.It is found that, nitrogen doping would hinder the growth of thin film, and generate the NOdefect, while magnesium doping promotes the quality of nitrogen-doped ZnO films, inhibiting（N_2）Oproduction and increasing nitrogen content.展开更多
A zinc oxide thin film in cubic crystalline phase, which is usually prepared under high pressure, has been grown on the Mg O（001） substrate by a three-step growth using plasma-assisted molecular beam epitaxy. The cu...A zinc oxide thin film in cubic crystalline phase, which is usually prepared under high pressure, has been grown on the Mg O（001） substrate by a three-step growth using plasma-assisted molecular beam epitaxy. The cubic structure is confirmed by in-situ reflection high energy electron diffraction measurements and simulations. The x-ray photoelectron spectroscopy reveals that the outer-layer surface of the film（less than 5 nm thick） is of ZnO phase while the buffer layer above the substrate is of ZnMgO phase, which is further confirmed by the band edge transmissions at the wavelengths of about 390 nm and 280 nm, respectively. The x-ray diffraction exhibits no peaks related to wurtzite ZnO phase in the film. The cubic ZnO film is presumably considered to be of the rock-salt phase. This work suggests that the metastable cubic ZnO films, which are of applicational interest for p-type doping, can be epitaxially grown on the rock-salt substrates without the usually needed high pressure conditions.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.69576022Natural Science Foundation of Fujian Province of China。
文摘Fine structure in the electron emission process for DX(Sn)centers in AlGaAs has been studied with high resolution Laplace defect spectroscopy.The influence of the different local configuration of Al and Ga atoms around the centers on the electron thermal emissions was observed.An experimental evidence for the microscopic structure of two DX-like centers in Sn-doped AlGaAs is provided.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204253,U1332105,61227009,and 91321102)the Fundamental Research Funds for Central Universities,China(Grant No.20720160020)the National High Technology Research and Development Program of China(Grant No.2014AA052202)
文摘Undoped ZnO and doped ZnO films were deposited on the MgO（111） substrates using oxygen plasma-assisted molecular beam expitaxy. The orientations of the grown ZnO thin film were investigated by in situ reflection high-energy electron diffraction and ex situ x-ray diffraction（XRD）. The film roughness was measured by atomic force microscopy, which was correlated with the grain sizes determined by XRD. Synchrotron-based x-ray absorption spectroscopy was performed to study the doping effect on the electronic properties of the ZnO films, compared with density functional theory calculations.It is found that, nitrogen doping would hinder the growth of thin film, and generate the NOdefect, while magnesium doping promotes the quality of nitrogen-doped ZnO films, inhibiting（N_2）Oproduction and increasing nitrogen content.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204253,U1232110,U1332105,61227009,and 91321102)the Fundamental Research Funds for Central Universities,China(Grant No.2013SH001)the National High Technology Research and Development Program of China(Grant No.2014AA052202)
文摘A zinc oxide thin film in cubic crystalline phase, which is usually prepared under high pressure, has been grown on the Mg O（001） substrate by a three-step growth using plasma-assisted molecular beam epitaxy. The cubic structure is confirmed by in-situ reflection high energy electron diffraction measurements and simulations. The x-ray photoelectron spectroscopy reveals that the outer-layer surface of the film（less than 5 nm thick） is of ZnO phase while the buffer layer above the substrate is of ZnMgO phase, which is further confirmed by the band edge transmissions at the wavelengths of about 390 nm and 280 nm, respectively. The x-ray diffraction exhibits no peaks related to wurtzite ZnO phase in the film. The cubic ZnO film is presumably considered to be of the rock-salt phase. This work suggests that the metastable cubic ZnO films, which are of applicational interest for p-type doping, can be epitaxially grown on the rock-salt substrates without the usually needed high pressure conditions.
