The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 an...The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 and 600°C.The values of the cross point between the curves of the real and imaginary parts of the optical conductivity ɑ_1 and ɑ_1 with energy axis of films exhibit values that correspond to optical gaps and are about 3.25-3.3 eV. The maxima of peaks in plots dR/dλ and dT/dλ versus wavelength of films exhibit optical gaps at about 3.12-3.25 eV.The values of the fundamental indirect band gap obtained from the Tauc model are at about 3.14-3.2 eV. It can be seen that films annealed at 600°C have the minimum indirect optical band gap at about 3.15 eV. The films annealed at 600°C have Urbach＇s energy minimum of 1.38 eV and hence have minimum disorder. The dispersion energy d of films annealed at 500°C has the minimum value of 43 eV.展开更多
Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range o...Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range of400-500 K shows the extended state conduction.The conductivity data in the temperature range of 150-300 K shows the multi-phonon hopping conduction.The Berthelot-type conduction dominates in the temperature range of 50-150 K.The conductivity of the films in the temperature range about 〈 50 K is described in terms of variable-range hopping conduction.In low temperatures,the localized density of state around Fermi level（F）for the film deposition with 3.92% nickel has a maximum value of about 56.2×10^（17）cm^（-3）eV^（-1） with the minimum average hopping distance of about 3.43 × 10^（-6） cm.展开更多
In this work, the optical absorption spectra of carbon-nickel films annealed at different temperatures（300-1000 ℃） with a special emphasis on the surface plasmon resonance（SPR） were investigated. The films were g...In this work, the optical absorption spectra of carbon-nickel films annealed at different temperatures（300-1000 ℃） with a special emphasis on the surface plasmon resonance（SPR） were investigated. The films were grown on quartz substrates by radio-frequency（RF）magnetron co-sputtering at room temperature with a deposition time of 600 s. The optical absorption peaks due to the SPR of Ni particle are observed in the wavelength range of 300-330 nm. With annealing temperature increasing up to 500 ℃ due to the increase in Ni particle size, the intensity of the SPR peaks increases, but weakens with annealing temperature increasing over 500 ℃. The Ni nanoparticle size, the dielectric function of carbon matrix（ε_m） and the plasma frequency of the free electrons（ω_p） at500 ℃have the maximum values of 21.63 nm, 0.471 and5.26 9 10^（15）s^（-1）, respectively. The absorption peak shows a redshift trend up to 500 ℃and then turn to blueshift with annealing temperature increasing over 500 ℃ These observations are in a good agreement with the electrical measurements in temperature range of 15-520 K and the Maxwell-Garnett（M-G） effective medium theory（EMT）.展开更多
In this work, the electrical properties of car- bon-nickel composite films deposited at different time （50-600 s） were investigated. The films were grown by radio frequency magnetron sputtering on glass substrates a...In this work, the electrical properties of car- bon-nickel composite films deposited at different time （50-600 s） were investigated. The films were grown by radio frequency magnetron sputtering on glass substrates at room temperature. The electrical conductivity of the films was investigated in the temperature range of 15-500 K. The conductivity data in the temperature range of 400-500 K show the extended state conduction mecha- nism, while the multiphonon hopping （MPH） conduction is found to dominate the electrical transport in the tempera- ture range of 150-300 K. The films deposited at 180 s have the maximum conductivity. The conductivity at T 〈 60 K could be described in terms of variable range hopping （VRH） conduction. The localized state density around Fermi level （N（EF）） at low temperature for the films deposited at 180 s has the minimum value of about 4.02 × 10^21 cm^-3.eV^-1. The average hopping distance （Rhop） for the films deposited at 180 s has the maximum value of about 3.51 × 10^-7 cm.展开更多
文摘The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 and 600°C.The values of the cross point between the curves of the real and imaginary parts of the optical conductivity ɑ_1 and ɑ_1 with energy axis of films exhibit values that correspond to optical gaps and are about 3.25-3.3 eV. The maxima of peaks in plots dR/dλ and dT/dλ versus wavelength of films exhibit optical gaps at about 3.12-3.25 eV.The values of the fundamental indirect band gap obtained from the Tauc model are at about 3.14-3.2 eV. It can be seen that films annealed at 600°C have the minimum indirect optical band gap at about 3.15 eV. The films annealed at 600°C have Urbach＇s energy minimum of 1.38 eV and hence have minimum disorder. The dispersion energy d of films annealed at 500°C has the minimum value of 43 eV.
文摘Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range of400-500 K shows the extended state conduction.The conductivity data in the temperature range of 150-300 K shows the multi-phonon hopping conduction.The Berthelot-type conduction dominates in the temperature range of 50-150 K.The conductivity of the films in the temperature range about 〈 50 K is described in terms of variable-range hopping conduction.In low temperatures,the localized density of state around Fermi level（F）for the film deposition with 3.92% nickel has a maximum value of about 56.2×10^（17）cm^（-3）eV^（-1） with the minimum average hopping distance of about 3.43 × 10^（-6） cm.
文摘In this work, the optical absorption spectra of carbon-nickel films annealed at different temperatures（300-1000 ℃） with a special emphasis on the surface plasmon resonance（SPR） were investigated. The films were grown on quartz substrates by radio-frequency（RF）magnetron co-sputtering at room temperature with a deposition time of 600 s. The optical absorption peaks due to the SPR of Ni particle are observed in the wavelength range of 300-330 nm. With annealing temperature increasing up to 500 ℃ due to the increase in Ni particle size, the intensity of the SPR peaks increases, but weakens with annealing temperature increasing over 500 ℃. The Ni nanoparticle size, the dielectric function of carbon matrix（ε_m） and the plasma frequency of the free electrons（ω_p） at500 ℃have the maximum values of 21.63 nm, 0.471 and5.26 9 10^（15）s^（-1）, respectively. The absorption peak shows a redshift trend up to 500 ℃and then turn to blueshift with annealing temperature increasing over 500 ℃ These observations are in a good agreement with the electrical measurements in temperature range of 15-520 K and the Maxwell-Garnett（M-G） effective medium theory（EMT）.
文摘In this work, the electrical properties of car- bon-nickel composite films deposited at different time （50-600 s） were investigated. The films were grown by radio frequency magnetron sputtering on glass substrates at room temperature. The electrical conductivity of the films was investigated in the temperature range of 15-500 K. The conductivity data in the temperature range of 400-500 K show the extended state conduction mecha- nism, while the multiphonon hopping （MPH） conduction is found to dominate the electrical transport in the tempera- ture range of 150-300 K. The films deposited at 180 s have the maximum conductivity. The conductivity at T 〈 60 K could be described in terms of variable range hopping （VRH） conduction. The localized state density around Fermi level （N（EF）） at low temperature for the films deposited at 180 s has the minimum value of about 4.02 × 10^21 cm^-3.eV^-1. The average hopping distance （Rhop） for the films deposited at 180 s has the maximum value of about 3.51 × 10^-7 cm.
