TY - JOUR
T1 - X-ray Photoelectron Spectroscopy Study of Indium Tin Oxide Films Deposited at Various Oxygen Partial Pressures
AU - Peng, Shou
AU - Cao, Xin
AU - Pan, Jingong
AU - Wang, Xinwei
AU - Tan, Xuehai
AU - Delahoy, Alan E.
AU - Chin, Ken K.
N1 - Funding Information:
The authors acknowledge the China Triumph International Engineering Co. Ltd. (CTIEC), Shanghai, China, which offers generous financial support for this work. The authors thank the Evans Analytical Group's Materials Characterization Division for the FIB-STEM analysis.
Publisher Copyright:
© 2016, The Minerals, Metals & Materials Society.
PY - 2017/2/1
Y1 - 2017/2/1
N2 - Here, a systematic experimental study on indium tin oxide (ITO) films is presented to investigate the effects of oxygen partial pressure on the film's electrical properties. The results of Hall measurements show that adding more oxygen in the sputtering gas has negative influences on the electrical conductivity of ITO films. As O2/(O2 + Ar)% in the sputtering gas is increased from 0 to 6.98%, the resistivity of ITO film rises almost exponentially from 7.9 × 10−4 to 4.1 × 10−2 Ω cm, with the carrier density decreasing from 4.8 × 1020 to 5.4 × 1018 cm−3. The origins of these negative effects are discussed with focuses on the concentration of ionized impurities and the scattering of grain barriers. Extensive x-ray photoelectron spectroscopy (XPS) analyses were employed to gain insight into the concentration of ionized impurities, demonstrating a strong correlation between the oxygen vacancy concentration and the carrier density in ITO films as a function of sputtering O2 partial pressure. Other microstructural characterization techniques including x-ray diffraction (XRD), high-magnification scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) analyses were used to evaluate the average grain size of ITO films. For ITO films that have carrier density above 1019 cm−3, scattering on grain boundaries and other crystallographic defects show negligible effects on the carrier transport. The results point to the oxygen vacancy concentration that dictates the carrier density and, thus, the resistivity of magnetron-sputtered ITO films.
AB - Here, a systematic experimental study on indium tin oxide (ITO) films is presented to investigate the effects of oxygen partial pressure on the film's electrical properties. The results of Hall measurements show that adding more oxygen in the sputtering gas has negative influences on the electrical conductivity of ITO films. As O2/(O2 + Ar)% in the sputtering gas is increased from 0 to 6.98%, the resistivity of ITO film rises almost exponentially from 7.9 × 10−4 to 4.1 × 10−2 Ω cm, with the carrier density decreasing from 4.8 × 1020 to 5.4 × 1018 cm−3. The origins of these negative effects are discussed with focuses on the concentration of ionized impurities and the scattering of grain barriers. Extensive x-ray photoelectron spectroscopy (XPS) analyses were employed to gain insight into the concentration of ionized impurities, demonstrating a strong correlation between the oxygen vacancy concentration and the carrier density in ITO films as a function of sputtering O2 partial pressure. Other microstructural characterization techniques including x-ray diffraction (XRD), high-magnification scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) analyses were used to evaluate the average grain size of ITO films. For ITO films that have carrier density above 1019 cm−3, scattering on grain boundaries and other crystallographic defects show negligible effects on the carrier transport. The results point to the oxygen vacancy concentration that dictates the carrier density and, thus, the resistivity of magnetron-sputtered ITO films.
KW - ITO
KW - XPS
KW - carrier concentration
KW - magnetron sputtering
KW - oxygen vacancy concentration
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U2 - 10.1007/s11664-016-5136-7
DO - 10.1007/s11664-016-5136-7
M3 - Article
AN - SCOPUS:84997610693
SN - 0361-5235
VL - 46
SP - 1405
EP - 1412
JO - Journal of Electronic Materials
JF - Journal of Electronic Materials
IS - 2
ER -