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ABSTRACT: By employing a relatively low growth temperature and oxygen-rich conditions, single-crystalline cubic MgZnO films were prepared. A solar-blind deep ultraviolet (DUV) photodetector was finished on the MgZnO film. The maximum responsivity of the photodetector is 396 mA/W at 10 V bias, which is almost three orders of magnitude larger than the highest value ever reported in MgZnO-based solar-blind photodetectors. The dark current density is 1.5×10−11 A/cm2, comparable with the smallest value ever reported in solar-blind photodetectors. The improved performance reveals that the single-crystalline cubic MgZnO films have great potential applications in DUV optoelectronic devices.
Applied Physics Letters 09/2009; 95(13):131113-131113-3. · 3.84 Impact Factor
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ABSTRACT: The phase stability of cubic Mg0.55Zn0.45O thin film grown by metal-organic chemical vapor deposition was studied through continuous thermal annealing. The crystal quality and surface smoothness were greatly improved after a continuous thermal annealing at 750 °C. It is attributed to the reducing of interstitial Zn by thermal annealing. However, phase segregation occurred when the sample was annealed at a higher temperature (850 °C), which is identified from both x-ray diffraction patterns and optical transmission spectra.
Applied Physics Letters 03/2009; 94(10):101902-101902-3. · 3.84 Impact Factor
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ABSTRACT: A series of MgxZn1−xO thin films has been prepared by metalorganic chemical vapor deposition and metal-semiconductor-metal structured ultraviolet photodetectors are fabricated from these films. The cutoff wavelengths of the photodetectors can cover the whole solar-blind spectrum range (220–280 nm) by varying Mg content in the MgxZn1−xO thin films. As a representative, the photodetector fabricated from Mg0.52Zn0.48O shows an ultraviolet/visible rejection ratio of about four orders of magnitude, and the dark current is 15 pA at 10 V bias. These results demonstrate that high-performance photodetectors operating in the whole solar-blind spectrum range can be realized in MgxZn1−xO films.
Applied Physics Letters 10/2008; 93(17):173505-173505-3. · 3.84 Impact Factor
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Z. G. Ju,
Y. M. Lu,
J. Y. Zhang,
X. J. Wu,
K. W. Liu,
B. S. Li,
D. X. Zhao,
Z. Z. Zhang,
B. H. Li,
B. Yao,
D. Z. Shen
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ABSTRACT: Diluted magnetic semiconductors Cd1−xFexSe were grown by metalorganic chemical vapor deposition. Their structure was studied by X-ray diffraction and selected area electron diffraction. The effect of Fe doping on the morphology and photoluminescence of CdSe was investigated. The photoluminescence study indicated that the crystalline structure of the Cd1−xFexSe films changed from a mixture of cubic and hexagonal phase to a single hexagonal phase with increasing Fe content.
07/2008;
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ABSTRACT: α - and β- Fe Se thin films were grown by metal organic chemical vapor deposition. Compared to the other parameters, the growth temperature shows decisive influence on the phase transition of the FeSe samples. In temperature-dependent electrical measurements, n -type to p -type reversion was observed for both the α - or and β- Fe Se samples. Furthermore, the p -type character of the films becomes more and more obvious with increasing the Se / Fe atomic ratio in the samples. Ferromagnetism was observed in the α- Fe Se films although which is not supported by calculation on density of states. The ferromagnetic character shows significant dependence on Se / Fe atomic ratio in the films and was attributed to the Fe vacancies or Fe clusters in the α- Fe Se thin films. The magnetic domain and hysteresis loop of the β- Fe Se thin films are also studied.
Journal of Applied Physics 07/2008; · 2.17 Impact Factor
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ABSTRACT: Cadmium selenide (CdSe) thin films were fabricated on c-sapphire and GaAs (1 0 0) substrates by low pressure metal organic chemical vapour deposition. The structural properties of these CdSe thin films were investigated by x-ray diffraction and photoluminescence spectroscopy. The effects of growth temperature (Tg) on the structural phase of the CdSe thin films were discussed. Phase transition of CdSe thin films grown on sapphire substrates from zincblende (ZB) to wurtzite (W) was observed with increasing Tg, and the transition critical temperature is 440 °C. However, the CdSe films grown on GaAs (1 0 0) keep ZB form in the whole range of Tg investigated from 300 to 500 °C.
Journal of Physics D Applied Physics 12/2007; 41(1):015304. · 2.54 Impact Factor
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ABSTRACT: A Mg0.48Zn0.52O thin film was deposited on a sapphire substrate by metal-organic chemical vapor deposition, and the thin film exhibits a single cubic phase with high crystal quality from X-ray diffraction measurements. A metal–semiconductor–metal (MSM) structured photodetector was fabricated on the film. The device exhibits a peak response of 268 nm with a cutoff wavelength at 283 nm. Rise and decay times of 10 ns and 150 ns, respectively, are obtained with a load resistance of . The pulse response for the device is limited by the RC time constant.
Solid State Communications 149:2021-2023. · 1.65 Impact Factor
