Vacuum evaporated films of cadium telluride have been prepared that show photovoltages as high as 100 v/cm of film length. An oblique angle of deposition of the vapor onto the substrate is required. The photovoltage saturates at high light intensities and low temperatures. At all other light intensities and temperatures it has the same functional dependence on light intensity as that of ordinary p-n junctions. The short-circuit current varies linearly with light intensity at all temperatures and is only weakly temperature-dependent. Analysis of the data suggests a series of p-n junctions (or other photovoltaic elements) arrayed in an additive manner. Estimates of the linear density of photovoltaic elements based on the measurements described above vary from ∼200/cm at room temperature to ∼7000/cm at −170°C. A possible mechanism to explain the effect is proposed, based on an anisotropic growth of crystallites due to the angle of deposition, and on the presence of residual gases in the vacuum chamber.

It is surprising that the assumption that all scattered quanta of one group have the same energy yields results so closely in agreement with experiments on both intensity and spectral distribution of the radiation. The meaning of this assumption in terms of the energy distribution is illustrated in Fig. 7, in which the number of quanta with energy greater than E has been plotted. This number increases by N whenever F. passes through one of the energies EI". . The same number has been computed from a statistical study of 200 calculated y-ray tracks by Dr. Fano and Mr. Karr at the National Bureau of Standards and is also shown in Fig. 7. The similarity of the two curves accounts for the close agreement between our experimental and calculated results.'Ke are indebted to Dr. Fano and Mr. Karr for permission to quote the results of their work on an OfFice @&hen thin films of insulating material are bombarded by high velocity electron beams that can penetrate through the thickness of the film, steady currents can be obtained that are as much as 100 times that in the bombarding beam. These currents vary with the gradient across the film and are proportional to the fraction of the beam energy absorbed in the film. Typical data obtained with amorphous silica are presented, together with a description of the experimental procedures that were used. v ere prepared by heating the plates in .in;itniosphere of ethyl silicate vapor, which (Iecon&poses

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