High-Voltage Photovoltaic Effect

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Abstract
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.