TY - JOUR
T1 - Electro-optical properties of thin indium tin oxide films
T2 - Limitations on performance
AU - Dhere, R. G.
AU - Gessert, T. A.
AU - Schilling, L. L.
AU - Nelson, A. J.
AU - Jones, K. M.
AU - Aharoni, H.
AU - Coutts, T. J.
N1 - Funding Information:
Our thanks are due to R. Noufi and his group for assistance with the ion beam sputtering system and to D. Williamson of the Colorado School of Mines for his help with the X-ray diffraction analysis. This work was supported by the U.S. Department of Energy under Contract DE-AC02-83CH-10093.
PY - 1987/1/1
Y1 - 1987/1/1
N2 - This work has been concerned with the measurement and analysis of the electro-optical properties of thin films of indium tin oxide deposited by ion beam sputtering. In the present context, the principal use of these films is for window layer solar cells, and it is necessary to have an accurate knowledge of the optical and electrical properties, and of their dependence on deposition conditions, to enable realistic predictions of the internal quantum efficiency to be made. We have measured the properties of films as a function of deposition rate, partial pressure of oxygen in the sputtering gas and annealing temperature. The properties studied are the variation with wavelength of the optical constants, the Hall mobility, the film structure and composition. The compositional data (from X-ray photoemission spectroscopy) suggest that heat treatment changes the state of oxidation of tin from SnO to SnO2-x, the oxygen vacancies acting as doubly ionized donors. At high partial pressures of oxygen and low densities of free carriers, the mobility is limited by grain boundary scattering, the magnitude of which is determined by the deposition conditions. For ennealed films with higher carrier densities, the optical and electrical data suggest that ionized impurity scattering is the mechanism limiting the mobility. These two mechanisms thus appear to impose a lower limit on the resistivity achievable in this material.
AB - This work has been concerned with the measurement and analysis of the electro-optical properties of thin films of indium tin oxide deposited by ion beam sputtering. In the present context, the principal use of these films is for window layer solar cells, and it is necessary to have an accurate knowledge of the optical and electrical properties, and of their dependence on deposition conditions, to enable realistic predictions of the internal quantum efficiency to be made. We have measured the properties of films as a function of deposition rate, partial pressure of oxygen in the sputtering gas and annealing temperature. The properties studied are the variation with wavelength of the optical constants, the Hall mobility, the film structure and composition. The compositional data (from X-ray photoemission spectroscopy) suggest that heat treatment changes the state of oxidation of tin from SnO to SnO2-x, the oxygen vacancies acting as doubly ionized donors. At high partial pressures of oxygen and low densities of free carriers, the mobility is limited by grain boundary scattering, the magnitude of which is determined by the deposition conditions. For ennealed films with higher carrier densities, the optical and electrical data suggest that ionized impurity scattering is the mechanism limiting the mobility. These two mechanisms thus appear to impose a lower limit on the resistivity achievable in this material.
UR - http://www.scopus.com/inward/record.url?scp=0022737879&partnerID=8YFLogxK
U2 - 10.1016/0379-6787(87)90127-X
DO - 10.1016/0379-6787(87)90127-X
M3 - Article
AN - SCOPUS:0022737879
SN - 0379-6787
VL - 21
SP - 281
EP - 290
JO - Solar Cells
JF - Solar Cells
IS - 1-4
ER -