TY - JOUR
T1 - Transparent and semitransparent conducting film deposition by reactive-environment, hollow cathode sputtering
AU - Delahoy, A. E.
AU - Guo, S. Y.
N1 - Funding Information:
The authors would like to acknowledge Y. Yoshida, C. Teplin, D. Ginley, T. Coutts, and C. Perkins of NREL, and Y. Sun and C. J. Li of NanKai University for film characterization (Hall effect, XPS, and transmission). The development of RE-HCS was supported by ATP award 70NANB0H3010 from NIST. Further TCO development was partially supported by the New Jersey Board of Public Utilities through the Clean Energy Program. We thank R. Lyndall of EPV for cathode design.
PY - 2005/7
Y1 - 2005/7
N2 - Highly transparent and conductive In2 O3 and ZnO films containing different doping elements such as Ti, Mo, Zr, Nb, Ta, W (for In2 O3), and B (for ZnO) have been prepared by reactive-environment, hollow cathode sputtering (RE-HCS). The use of Nb and W as effective dopants is reported for the first time. Metallic targets were used exclusively, and the dopant concentration was easily controlled using a second sputtering power supply. As a result of the cathode and gas flow geometry, the sputtering is conducted in metal mode, and the target and doping materials are free from oxidation during the deposition process. Film resistivities achieved with the various dopants are reported. For In2 O3: Mo (IMO), a resistivity of 1.6× 10-4 Ω cm and a mobility of 80 cm2 Vs were achieved for Mo concentrations in the range 0.5-5.0% as measured by inductively coupled plasma (ICP). X-ray photoelectron spectroscopy (XPS) analysis indicates Mo with a +6 valence state and that the film is stoichiometric. For In2 O3: Ti (ITiO), a superior optical transmission is achieved relative to IMO, while carrier mobility and conductivity were similar. Remarkably, semitransparent films of InN:O having sheet resistances of 9.5 Ωsquare have also been prepared. ZnO:B films deposited by RE-HCS exhibit superior optical properties relative to ZnO:Al, and when applied as a window layer to CIGS solar cells yield higher quantum efficiencies.
AB - Highly transparent and conductive In2 O3 and ZnO films containing different doping elements such as Ti, Mo, Zr, Nb, Ta, W (for In2 O3), and B (for ZnO) have been prepared by reactive-environment, hollow cathode sputtering (RE-HCS). The use of Nb and W as effective dopants is reported for the first time. Metallic targets were used exclusively, and the dopant concentration was easily controlled using a second sputtering power supply. As a result of the cathode and gas flow geometry, the sputtering is conducted in metal mode, and the target and doping materials are free from oxidation during the deposition process. Film resistivities achieved with the various dopants are reported. For In2 O3: Mo (IMO), a resistivity of 1.6× 10-4 Ω cm and a mobility of 80 cm2 Vs were achieved for Mo concentrations in the range 0.5-5.0% as measured by inductively coupled plasma (ICP). X-ray photoelectron spectroscopy (XPS) analysis indicates Mo with a +6 valence state and that the film is stoichiometric. For In2 O3: Ti (ITiO), a superior optical transmission is achieved relative to IMO, while carrier mobility and conductivity were similar. Remarkably, semitransparent films of InN:O having sheet resistances of 9.5 Ωsquare have also been prepared. ZnO:B films deposited by RE-HCS exhibit superior optical properties relative to ZnO:Al, and when applied as a window layer to CIGS solar cells yield higher quantum efficiencies.
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U2 - 10.1116/1.1894423
DO - 10.1116/1.1894423
M3 - Article
AN - SCOPUS:31044432789
SN - 0734-2101
VL - 23
SP - 1215
EP - 1220
JO - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
JF - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
IS - 4
ER -