Abstract:We report the dependence of electrical properties of Fe-O-N thin films on the deposition condition as well as on O 2 and N 2 gas flow rate. Fe-O-N films were deposited by reactive sputtering using O 2 and N 2 as reactive gas. The electrical resistivity of Fe-O-N films increased with increasing O 2 and N 2 gas flow rate. The resistivity increase with the O 2 flow rate was due to structure change from a mixed phase of metallic Fe+Fe 3 O 4 , to a mixed phase of FeO+¡-Fe 2 O 3 , and to a single phase of ¡-Fe 2 O 3… Show more
“…The shape of the Fe 2p spectrum at 25 • C obtained in our present experiment was very similar to that of the Fe 2p spectrum in the low-O 2 flow rate stage in the range of 705−725 eV as shown in Figure 3a in Reference [20], except for the shift in binding energy. In Reference [20], at higher O 2 flow rates, a mixed phase of FeO and α-Fe 2 O 3 with a satellite peak at 718.9 eV, and α-Fe 2 O 3 with a satellite peak at 719.2 eV were observed, respectively. Therefore, this suggests that the structure of the scratched surface at 25 • C may be composed predominantly of a mixed phase of metallic Fe and Fe 3 O 4 .…”
“…The XPS measurement was carried out after the PE measurement at 25, 200, and 339 • C for real iron surfaces scratched in the environments. Although we already reported the change of Fe 2p and Fe 3p spectra with the increasing temperature for the scratched samples [6], in the present study, according to References [15][16][17][18][19][20], we reexamined in more detail the dependence of Fe 2p spectra on temperature and scratching environments. The intensities and binding energies of peaks-called Peaks I, II, and III-observed in the Fe 2p spectra are listed in Table 1.…”
“…Ogawa et al [20] reported Fe 2p spectra of Fe−O−N films formed by sputtering iron metal at different O 2 flow rates (f O2 ) in an Ar−N 2 −O 2 gas mixture, and explained that the film structure with increasing O 2 flow rate changes from a mixed phase of metallic Fe and Fe 3 O 4 initially, to a mixed phase of FeO and α-Fe 2 O 3 , and finally, to α-Fe 2 O 3 . The shape of the Fe 2p spectrum at 25 • C obtained in our present experiment was very similar to that of the Fe 2p spectrum in the low-O 2 flow rate stage in the range of 705−725 eV as shown in Figure 3a in Reference [20], except for the shift in binding energy. In Reference [20], at higher O 2 flow rates, a mixed phase of FeO and α-Fe 2 O 3 with a satellite peak at 718.9 eV, and α-Fe 2 O 3 with a satellite peak at 719.2 eV were observed, respectively.…”
Little is known about the temperature dependence of electron transfer occurring at real metal surfaces. For iron surfaces scratched in seven environments, we report Arrhenius activation energies obtained from the data of photoelectron emission (PE) and X-ray photoelectron spectroscopy (XPS). The environments were air, benzene, cyclohexane, water, methanol, ethanol, and acetone. PE was measured using a modified Geiger counter during repeated temperature scans in the 25–339 °C range under 210-nm-wavelength light irradiation and during light wavelength scans in the range 300 to 200 nm at 25, 200, and 339 °C. The standard XPS measurement of Fe 2p, Fe 3p, O 1s, and C 1s spectra was conducted after wavelength scan. The total number of electrons counted in the XPS measurement of the core spectra, which was called XPS intensity, strongly depended on the environments. The PE quantum yields during the temperature scan increased with temperature, and its activation energies (ΔEaUp1) strongly depended on the environment, being in the range of 0.212 to 0.035 eV. The electron photoemission probability (αA) obtained from the PE during the wavelength scan increased with temperature, and its activation energies (ΔEαA) were almost independent of the environments, being in the range of 0.113–0.074 eV. The environment dependence of the PE behavior obtained from temperature and wavelength scans was closely related to that of the XPS characteristics, in particular, the XPS intensities of O 1s and the O2− component of the O 1s spectrum, the acid–base interaction between the environment molecule and Fe–OH, and the growth of non-stoichiometric FexO. Furthermore, the origin of the αA was attributed to the escape depth of hot electrons across the overlayer.
“…The shape of the Fe 2p spectrum at 25 • C obtained in our present experiment was very similar to that of the Fe 2p spectrum in the low-O 2 flow rate stage in the range of 705−725 eV as shown in Figure 3a in Reference [20], except for the shift in binding energy. In Reference [20], at higher O 2 flow rates, a mixed phase of FeO and α-Fe 2 O 3 with a satellite peak at 718.9 eV, and α-Fe 2 O 3 with a satellite peak at 719.2 eV were observed, respectively. Therefore, this suggests that the structure of the scratched surface at 25 • C may be composed predominantly of a mixed phase of metallic Fe and Fe 3 O 4 .…”
“…The XPS measurement was carried out after the PE measurement at 25, 200, and 339 • C for real iron surfaces scratched in the environments. Although we already reported the change of Fe 2p and Fe 3p spectra with the increasing temperature for the scratched samples [6], in the present study, according to References [15][16][17][18][19][20], we reexamined in more detail the dependence of Fe 2p spectra on temperature and scratching environments. The intensities and binding energies of peaks-called Peaks I, II, and III-observed in the Fe 2p spectra are listed in Table 1.…”
“…Ogawa et al [20] reported Fe 2p spectra of Fe−O−N films formed by sputtering iron metal at different O 2 flow rates (f O2 ) in an Ar−N 2 −O 2 gas mixture, and explained that the film structure with increasing O 2 flow rate changes from a mixed phase of metallic Fe and Fe 3 O 4 initially, to a mixed phase of FeO and α-Fe 2 O 3 , and finally, to α-Fe 2 O 3 . The shape of the Fe 2p spectrum at 25 • C obtained in our present experiment was very similar to that of the Fe 2p spectrum in the low-O 2 flow rate stage in the range of 705−725 eV as shown in Figure 3a in Reference [20], except for the shift in binding energy. In Reference [20], at higher O 2 flow rates, a mixed phase of FeO and α-Fe 2 O 3 with a satellite peak at 718.9 eV, and α-Fe 2 O 3 with a satellite peak at 719.2 eV were observed, respectively.…”
Little is known about the temperature dependence of electron transfer occurring at real metal surfaces. For iron surfaces scratched in seven environments, we report Arrhenius activation energies obtained from the data of photoelectron emission (PE) and X-ray photoelectron spectroscopy (XPS). The environments were air, benzene, cyclohexane, water, methanol, ethanol, and acetone. PE was measured using a modified Geiger counter during repeated temperature scans in the 25–339 °C range under 210-nm-wavelength light irradiation and during light wavelength scans in the range 300 to 200 nm at 25, 200, and 339 °C. The standard XPS measurement of Fe 2p, Fe 3p, O 1s, and C 1s spectra was conducted after wavelength scan. The total number of electrons counted in the XPS measurement of the core spectra, which was called XPS intensity, strongly depended on the environments. The PE quantum yields during the temperature scan increased with temperature, and its activation energies (ΔEaUp1) strongly depended on the environment, being in the range of 0.212 to 0.035 eV. The electron photoemission probability (αA) obtained from the PE during the wavelength scan increased with temperature, and its activation energies (ΔEαA) were almost independent of the environments, being in the range of 0.113–0.074 eV. The environment dependence of the PE behavior obtained from temperature and wavelength scans was closely related to that of the XPS characteristics, in particular, the XPS intensities of O 1s and the O2− component of the O 1s spectrum, the acid–base interaction between the environment molecule and Fe–OH, and the growth of non-stoichiometric FexO. Furthermore, the origin of the αA was attributed to the escape depth of hot electrons across the overlayer.
“…This attributes a semiconductor behavior for these films. It is wellknown that α-Fe 2 O 3 (hematite) is a n-type semiconductor [37]. However, according to Morikawa et al and Ogawa et al [37,38], it can change to p-type conduction induced by N-doping in α-Fe 2 O 3 .…”
Section: Electrical Propertiesmentioning
confidence: 99%
“…It is wellknown that α-Fe 2 O 3 (hematite) is a n-type semiconductor [37]. However, according to Morikawa et al and Ogawa et al [37,38], it can change to p-type conduction induced by N-doping in α-Fe 2 O 3 . Since we did not perform any hall effect measurements in this study, we can assume that our hematite-like films are of p-type.…”
Fe-O-N films were successfully deposited by magnetron sputtering of an iron target in Ar-N2-O2 reactive mixtures at high nitrogen partial pressure 1.11 Pa (Q(N2) = 8 sccm) using a constant flow rate of argon and an oxygen flow rate Q(O2) varying from 0 to 1.6 sccm. The chemical composition and the structural and microstructural nature of these films were characterized using Rutherford Backscattering Spectrometry, X-ray diffraction, and Conversion Electron Mössbauer Spectrometry, respectively. The results showed that the films deposited without oxygen are composed of a single phase of γ″-FeN, whereas the other films do not consist of pure oxides but oxidelike oxynitrides. With higher oxygen content, the films are well-crystallized in the α-Fe2O3 structure. At intermediate oxygen flow rate, the films are rather poorly crystallized and can be described as a mixture of oxide γ-Fe2O3/Fe3O4. In addition, the electrical behavior of the films evolved from a metallic one to a semiconductor one, which is in total agreement with other investigations. Comparatively to a previous study carried out at low nitrogen partial pressure (0.25 Pa), this behavior of films prepared at higher nitrogen partial pressure (1.11 Pa) could be caused by a catalytic effect of nitrogen on the crystallization of the hematite structure.
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