Studies for Predictably Modifying the Optical Constants of Doped Indium Oxide Films for Solar Energy Applications. Semi-Annual Report, 5 June 1978-31 December 1978

摘要

During the first six months, undoped, tin-doped and boron-doped indium oxide film samples (on fused silica substrates) have been prepared by spray pyrolysis for possible photothermal and photovoltaic applications. Evaluations have been made with various pieces of apparatus, some of which is undergoing development. This includes: electrical conductivity and Hall mobility measurements, optical transmission versus wavelength measurements, Brewster angle measurements at 633 nm wavelength, and x-ray diffraction measurements. Mobilities for undoped and tin-doped samples are usually approximately 10 cm exp 2 V exp -1 sec exp -1 ; the lattice constants for these same samples are slightly less than 10.1 A; the optical absorption edge for the as-deposited samples is approximately 3.5 eV; and the refractive index at 633 nm is approximately 2.0-2.1. For the few samples that have been prepared with boron doping, the lattice constant appears to decrease (and long-range order disappears for heavy boron concentrations); the absorption edge moves to higher energies; and the refractive index (at 633 nm) decreases. Two classical dielectric models have been invoked to explain the refractive index decrease; one model assumes an admixing of refractive indices of the component oxides, and the other model uses a modified additivity of the electronic polarizabilities of the component ions. The latter model yields predictions for the refractive index as a function of boron concentration which is in better agreement with experiment than that predicted by the former model. Consequently, it is tentatively suggested that boron is disordering the lattice while substituting for indium. (ERA citation 05:006777)