We report deep level transient spectroscopy results from ZnO layers grown on silicon by molecular beam epitaxy （MBE）, The hot probe measurements reveal mixed conductivity in the as-grown ZnO layers, and the current-...We report deep level transient spectroscopy results from ZnO layers grown on silicon by molecular beam epitaxy （MBE）, The hot probe measurements reveal mixed conductivity in the as-grown ZnO layers, and the current-voltage （l-V） measurements demonstrate a good quality p-type Schottky device. A new deep acceptor level is observed in the ZnO layer having activation energy of 0.49 ± 0.03 eV and capture cross-section of 8,57 ×10^-18 cm^2. Based on the results from Raman spectroscopy, photoluminescence, and secondary ion mass spectroscopy （SIMS） of the ZnO layer, the observed acceptor trap level is tentatively attributed to a nitrogen-zinc vacancy complex in ZnO,展开更多
We have demonstrated the effect of annealing temperature on the diffusion density of phosphors in zinc oxide. The P-dopant P430 was sprayed on ZnO pellets and annealed at different temperatures from 500 to 1000 ℃ wit...We have demonstrated the effect of annealing temperature on the diffusion density of phosphors in zinc oxide. The P-dopant P430 was sprayed on ZnO pellets and annealed at different temperatures from 500 to 1000 ℃ with a step of 100 ℃ for one hour using a programmable furnace. The concentration of P was controlled by varying the annealing temperature and the maximum solubility of P （3% At） was achieved at annealing 800 ℃ determined by energy dispersive X-ray diffraction （EDX） measurements. X-ray diffraction （XRD） confirmed the hexagonal structure of ZnO and showed that the growth direction was along the c-axis. We observed a maximum up shift in the （002） plane at an annealing temperature of 800 ℃, suggesting that P atoms replaced Zn atoms in the structure which results in the reduction of the lattice constant. Room temperature photoluminescence （PL） spectrum consists of a peak at 3.28 eV and related to band edge emission, but samples annealed at 800 and 900 ℃ have an additional donor acceptor pair peak at 3.2 eV. Hall effect measurements confirmed the p-type conductivity of the sample annealed at 800 ℃.展开更多
We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by high- temperature thermal annealing. The ZnS thin films were grown on Si （001） substrate by thermal evaporation system using Zn...We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by high- temperature thermal annealing. The ZnS thin films were grown on Si （001） substrate by thermal evaporation system using ZnS powder as source material. The grown films were annealed at different temperatures and characterized by X-ray diffraction （XRD）, photoluminescence （PL）, four-point probe, scanning electron microscope （SEM） and energy dispersive X-ray diffraction （EDX）. The results demonstrated that as-deposited ZnS film has mixed phases but high-temperature annealing leads to transition from ZnS to ZnO. The observed result can be explained as a two- step process： （1） high-energy O atoms replaced S atoms in lattice during annealing process, and （2） S atoms diffused into substrate and/or diffused out of the sample. The dissociation energy of ZnS calculated from the Arrhenius plot of 1000/T versus log （resistivity） was found to be 3.1 eV. PL spectra of as-grown sample exhibits a characteristic green emission at 2.4 eV of ZnS but annealed samples consist of band-to-band and defect emission of ZnO at 3.29 eV and 2.5 eV respectively. SEM and EDX measurements were additionally performed to strengthen the argument.展开更多
文摘We report deep level transient spectroscopy results from ZnO layers grown on silicon by molecular beam epitaxy （MBE）, The hot probe measurements reveal mixed conductivity in the as-grown ZnO layers, and the current-voltage （l-V） measurements demonstrate a good quality p-type Schottky device. A new deep acceptor level is observed in the ZnO layer having activation energy of 0.49 ± 0.03 eV and capture cross-section of 8,57 ×10^-18 cm^2. Based on the results from Raman spectroscopy, photoluminescence, and secondary ion mass spectroscopy （SIMS） of the ZnO layer, the observed acceptor trap level is tentatively attributed to a nitrogen-zinc vacancy complex in ZnO,
基金the Higher Education Commission (HEC) of Pakistan for the financial assistance under project # IPFP/HRD/HEC/2014/2016
文摘We have demonstrated the effect of annealing temperature on the diffusion density of phosphors in zinc oxide. The P-dopant P430 was sprayed on ZnO pellets and annealed at different temperatures from 500 to 1000 ℃ with a step of 100 ℃ for one hour using a programmable furnace. The concentration of P was controlled by varying the annealing temperature and the maximum solubility of P （3% At） was achieved at annealing 800 ℃ determined by energy dispersive X-ray diffraction （EDX） measurements. X-ray diffraction （XRD） confirmed the hexagonal structure of ZnO and showed that the growth direction was along the c-axis. We observed a maximum up shift in the （002） plane at an annealing temperature of 800 ℃, suggesting that P atoms replaced Zn atoms in the structure which results in the reduction of the lattice constant. Room temperature photoluminescence （PL） spectrum consists of a peak at 3.28 eV and related to band edge emission, but samples annealed at 800 and 900 ℃ have an additional donor acceptor pair peak at 3.2 eV. Hall effect measurements confirmed the p-type conductivity of the sample annealed at 800 ℃.
文摘We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by high- temperature thermal annealing. The ZnS thin films were grown on Si （001） substrate by thermal evaporation system using ZnS powder as source material. The grown films were annealed at different temperatures and characterized by X-ray diffraction （XRD）, photoluminescence （PL）, four-point probe, scanning electron microscope （SEM） and energy dispersive X-ray diffraction （EDX）. The results demonstrated that as-deposited ZnS film has mixed phases but high-temperature annealing leads to transition from ZnS to ZnO. The observed result can be explained as a two- step process： （1） high-energy O atoms replaced S atoms in lattice during annealing process, and （2） S atoms diffused into substrate and/or diffused out of the sample. The dissociation energy of ZnS calculated from the Arrhenius plot of 1000/T versus log （resistivity） was found to be 3.1 eV. PL spectra of as-grown sample exhibits a characteristic green emission at 2.4 eV of ZnS but annealed samples consist of band-to-band and defect emission of ZnO at 3.29 eV and 2.5 eV respectively. SEM and EDX measurements were additionally performed to strengthen the argument.
