TY - JOUR
T1 - Structure-Charge Transport Relationships in Fluoride-Doped Amorphous Semiconducting Indium Oxide
T2 - Combined Experimental and Theoretical Analysis
AU - Sil, Aritra
AU - Avazpour, Laleh
AU - Goldfine, Elise A.
AU - Ma, Qing
AU - Huang, Wei
AU - Wang, Binghao
AU - Bedzyk, Michael J.
AU - Medvedeva, Julia E.
AU - Facchetti, Antonio
AU - Marks, Tobin J.
N1 - Funding Information:
We thank the Northwestern Univ. (NU) MRSEC Grant No. NSF-DMR 1720139 for support of this research. J.E.M. thanks NSF-DMREF Grant No. 1729779 for support and the XSEDE center for computational facilities. This work made use of the EPIC, Keck-II, and/or SPID facility(ies) of the Northwestern Univ. NU ANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. XRR measurements used the NU XRD Facility also supported by the NSF MRSEC grant. This work used the 5-BM-D beamline of the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS). DND-CAT is supported by NU, E. I. DuPont de Nemours & Co., and The Dow Chemical Company. This research used resources of the APS, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. A.S. thanks Dr. V. Hedge of the Prof. C. Wolverton group and Dr. S. L. Moffitt (SLAC) for helpful discussions.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2020/1/28
Y1 - 2020/1/28
N2 - Anion doping of transparent amorphous metal oxide (a-MO) semiconductors is virtually unexplored but offers the possibility of creating unique optoelectronic materials owing to the chemical tuning, modified crystal structures, and unusual charge-transport properties that added anions may impart. We report here the effects of fluoride (F-) doping by combustion synthesis, in an archetypical metal oxide semiconductor, indium oxide (In-O). Optimized fluoride-doped In-O (F:In-O) thin films are characterized in depth by grazing incidence X-ray diffraction, X-ray reflectivity, atomic force microscopy, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure (EXAFS). Charge-transport properties are investigated in thin-film transistors (TFTs), revealing that increasing fluoride content (0.0 → 1.57 atom %) slightly lowers the on-current (Ion) and electron mobility due to scattering from loosely bound F- centers but enhances important TFT performance parameters such as the Ion/Ioff ratio, subthreshold swing, and bias stress stability, yielding superior TFT switching versus undoped In-O. These results are convincingly explained by ab initio molecular dynamics simulations and density functional theory electronic structure calculations. Combined with the EXAFS data, the experimental and theoretical results show that F- hinders crystallization by enhancing the local and medium-range disorder, promotes a uniform film morphology, and favors the formation of deeper, more localized trap states as compared to F--free In-O. These data also show that the local organization and electronic structure of amorphous F--doped oxide semiconductors are significantly different from those of F--doped crystalline oxide semiconductors and suggest new avenues to further modify a-MOs for enhanced optoelectronic properties.
AB - Anion doping of transparent amorphous metal oxide (a-MO) semiconductors is virtually unexplored but offers the possibility of creating unique optoelectronic materials owing to the chemical tuning, modified crystal structures, and unusual charge-transport properties that added anions may impart. We report here the effects of fluoride (F-) doping by combustion synthesis, in an archetypical metal oxide semiconductor, indium oxide (In-O). Optimized fluoride-doped In-O (F:In-O) thin films are characterized in depth by grazing incidence X-ray diffraction, X-ray reflectivity, atomic force microscopy, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure (EXAFS). Charge-transport properties are investigated in thin-film transistors (TFTs), revealing that increasing fluoride content (0.0 → 1.57 atom %) slightly lowers the on-current (Ion) and electron mobility due to scattering from loosely bound F- centers but enhances important TFT performance parameters such as the Ion/Ioff ratio, subthreshold swing, and bias stress stability, yielding superior TFT switching versus undoped In-O. These results are convincingly explained by ab initio molecular dynamics simulations and density functional theory electronic structure calculations. Combined with the EXAFS data, the experimental and theoretical results show that F- hinders crystallization by enhancing the local and medium-range disorder, promotes a uniform film morphology, and favors the formation of deeper, more localized trap states as compared to F--free In-O. These data also show that the local organization and electronic structure of amorphous F--doped oxide semiconductors are significantly different from those of F--doped crystalline oxide semiconductors and suggest new avenues to further modify a-MOs for enhanced optoelectronic properties.
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U2 - 10.1021/acs.chemmater.9b04257
DO - 10.1021/acs.chemmater.9b04257
M3 - Article
AN - SCOPUS:85078292769
VL - 32
SP - 805
EP - 820
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 2
ER -