TY - JOUR
T1 - Measurement method for carrier concentration in TiO2 via the Mott-Schottky approach
AU - Sellers, Meredith C.K.
AU - Seebauer, Edmund G.
N1 - Funding Information:
This work was carried out in part at the Center for Microanalysis of Materials at the Frederick Seitz Materials Research Laboratory, University of Illinois, which is partially supported by the U.S. Department of Energy (DE-FG02-07ER46453 and DE-FG02-07ER46471). We acknowledge funding from the National Science Foundation through a Graduate Research Fellowship (M.C.K.S.) and Grant DMR 07-04354 . We are grateful for the assistance of Mauro Sardela, Rick Haasch, Dane Sievers, and Edmond Chow.
PY - 2011/1/31
Y1 - 2011/1/31
N2 - In direct contrast to the way in which silicon is precisely doped for integrated circuit applications in order to optimize device performance, there is little nuanced understanding of the correlation between TiO2 doping level, charge carrier concentration, and the operation of TiO 2-based photocatalysts, dye-sensitized solar cells, and sensors. The present work outlines a rigorous methodology for the determination of free carrier concentration for doped metal oxide semiconductors such as TiO 2 that are not amenable to standard metrology methods. Undoped, Cr-, Mn-, and Nb-doped polycrystalline anatase TiO2 are synthesized via atomic layer deposition (ALD) using Ti(OCH(CH3)2) 4, H2O, Cr(C5H7O2) 3, Mn(DPM)3 (DPM = 2,2,6,6-tetramethyl-3, 5-heptanedionato), and Nb(OCH2CH3)5 as the source materials for Ti, O, Cr, Mn, and Nb, respectively. Chemical composition and crystallinity are investigated and a thorough "device-like" characterization of TiO2 Schottky diodes is carried out to justify the subsequent extraction of carrier concentration values from capacitance-voltage (C-V) measurements using the Mott-Schottky approach. The influence of factors such as substrate type, contact metal type, and surface and interface preparation are examined. Measurements of donor carrier concentration are obtained for undoped, Cr-, Mn-, and Nb-doped TiO2 synthesized by ALD. Possible causes for the obtained carrier concentrations are discussed.
AB - In direct contrast to the way in which silicon is precisely doped for integrated circuit applications in order to optimize device performance, there is little nuanced understanding of the correlation between TiO2 doping level, charge carrier concentration, and the operation of TiO 2-based photocatalysts, dye-sensitized solar cells, and sensors. The present work outlines a rigorous methodology for the determination of free carrier concentration for doped metal oxide semiconductors such as TiO 2 that are not amenable to standard metrology methods. Undoped, Cr-, Mn-, and Nb-doped polycrystalline anatase TiO2 are synthesized via atomic layer deposition (ALD) using Ti(OCH(CH3)2) 4, H2O, Cr(C5H7O2) 3, Mn(DPM)3 (DPM = 2,2,6,6-tetramethyl-3, 5-heptanedionato), and Nb(OCH2CH3)5 as the source materials for Ti, O, Cr, Mn, and Nb, respectively. Chemical composition and crystallinity are investigated and a thorough "device-like" characterization of TiO2 Schottky diodes is carried out to justify the subsequent extraction of carrier concentration values from capacitance-voltage (C-V) measurements using the Mott-Schottky approach. The influence of factors such as substrate type, contact metal type, and surface and interface preparation are examined. Measurements of donor carrier concentration are obtained for undoped, Cr-, Mn-, and Nb-doped TiO2 synthesized by ALD. Possible causes for the obtained carrier concentrations are discussed.
KW - Anatase
KW - Atomic layer deposition
KW - Capacitance-voltage
KW - Carrier concentration
KW - Metal oxide semiconductor
KW - Titanium oxide
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U2 - 10.1016/j.tsf.2010.10.071
DO - 10.1016/j.tsf.2010.10.071
M3 - Article
AN - SCOPUS:78751647203
SN - 0040-6090
VL - 519
SP - 2103
EP - 2110
JO - Thin Solid Films
JF - Thin Solid Films
IS - 7
ER -