The temperature dependence of the Hall constant, resistivity, and Hall mobility was measured for Ge films deposited on polished (111) CaF2 substrates at substrate temperatures of 200°–700°C, deposition rates of 100–15 000 Å/min, and for film thicknesses between 800 and 170 000 Å. For formation conditions which improved film structures, electrical properties likewise improved. For single-crystal films the Hall constant and Hall mobility increased as the defect density decreased with increasing deposition temperature and decreasing deposition rate. Similarly, for films thicker than 4000 Å, as the density of defects intersecting the surface decreased with increasing thickness, the Hall constant and mobility increased. Hole-carrier concentrations of 1016–1018 per cm3 and room-temperature Hall mobilities of 100–1100 cm2/V·sec were observed. The results indicate that defects are the source of acceptors and contribute significantly to scattering.
The electrical properties of solid‐state electrochemical cells using thin‐film lanthanum fluoride electrolyte have been investigated as a function of the ambient atmosphere. The conductivity of the cells has been found to increase with the concentration of the reducible gases O2,
CO2
,
SO2
,
NO2
, and
NO
. Sensitivity to a given gas is observed when the cell's terminal voltage exceeds a “characteristic potential” which correlates with the electron affinity of the gas. With suitable choice of anode material a galvanic cell is formed which may be used as a “self‐energized” O2 electrode or as a low current battery or O2 fuel cell.
The structure of Ge films deposited over a wide range of deposition rates and substrate temperatures onto hand-polished (111) CaF2 substrates in a vacuum of 10−9 to 4×10−7 Torr has been characterized. The epitaxial temperature and the amorphous to crystalline transition temperature were found to be rate dependent. The linear relation observed between the logarithm of the deposition rate and the reciprocal of the epitaxial temperature agrees generally with nucleation theory of small clusters and yields an activation energy of 1.43 eV. The observed linear relation between the logarithm of the deposition rate and the reciprocal of the amorphous to crystalline transition temperature has been interpreted in terms of simple surface diffusion theory and leads to an activation energy for surface diffusion of Ge on CaF2 of 1.53 eV.
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