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Doping-free bandgap tunability in Fe 2 O 3 nanostructured films.

Authors :: Kadam SA
Phan GT
Pham DV
Patil RA
Lai CC
Chen YR
Liou Y
Ma YR
Source :: Nanoscale advances [Nanoscale Adv] 2021 Jul 29; Vol. 3 (19), pp. 5581-5588. Date of Electronic Publication: 2021 Jul 29 (Print Publication: 2021).
Publication Year :: 2021
Abstract: A tunable bandgap without doping is highly desirable for applications in optoelectronic devices. Herein, we develop a new method which can tune the bandgap without any doping. In the present research, the bandgap of Fe <subscript>2</subscript> O <subscript>3</subscript> nanostructured films is simply tuned by changing the synthesis temperature. The Fe <subscript>2</subscript> O <subscript>3</subscript> nanostructured films are synthesized on ITO/glass substrates at temperatures of 1100, 1150, 1200, and 1250 °C using the hot filament metal oxide vapor deposition (HFMOVD) and thermal oxidation techniques. The Fe <subscript>2</subscript> O <subscript>3</subscript> nanostructured films contain two mixtures of Fe <superscript>2+</superscript> and Fe <superscript>3+</superscript> cations and two trigonal (α) and cubic (γ) phases. The increase of the Fe <superscript>2+</superscript> cations and cubic (γ) phase with the elevated synthesis temperatures lifted the valence band edge, indicating a reduction in the bandgap. The linear bandgap reduction of 0.55 eV without any doping makes the Fe <subscript>2</subscript> O <subscript>3</subscript> nanostructured films promising materials for applications in bandgap engineering, optoelectronic devices, and energy storage devices.<br />Competing Interests: There are no conflicts to declare.<br /> (This journal is © The Royal Society of Chemistry.)