Electrical transport properties of Ti-doped Fe (0001) epitaxial films
The electrical transport properties for compositionally and structurally well-defined epitaxial α-(TixFe1-x)2O3(0001) films have been investigated for x ≤ 0.09. All films were grown by oxygen plasma-assisted molecular beam epitaxy using two different growth rates: 0.05–0.06 Å/s and 0.22–0.24 Å/s. Despite no detectable difference in cation valence and structural properties, films grown at the lower rate were highly resistive whereas those grown at the higher rate were semiconducting (ρ = ~1 Ω · cm at 25 °C). Hall effect measurements reveal carrier concentrations between 1019 and 1020 cm-3 at room temperature and mobilities in the range of 0.1 to 0.6 cm2/V · s for films grown at the higher rate. The conduction mechanism transitions from small-polaron hopping at higher temperatures to variable-range hopping at a transition temperature between 180 and 140 K. The absence of conductivity in the slow-grown films is attributed to donor electron compensation by cation vacancies, which may form to a greater extent at the lower rate because of higher oxygen fugacity at the growth front.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1034586
- Report Number(s):
- PNNL-SA-83375; PRBMDO; 35197; KC0203020; TRN: US201203%%636
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 84, Issue 24; ISSN 1098-0121
- Publisher:
- American Physical Society (APS)
- Country of Publication:
- United States
- Language:
- English
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