Abstract: A thin film solar cell having adjacent layers of P and N type polycrystalline semiconductor material which define a PN junction boundary, the improvement comprising a layer of n-type polycrystalline cadmium sulfide disposed on a chosen substrate material and having large grains with lateral grain boundaries on the order of about 20 micrometers or greater and a layer of polycrystalline P-type indium phosphide disposed on said layer of polycrystalline cadmium sulfide and having a thickness on the order of between 1.0 and 4.0 micrometers and further having large replicated grain boundaries with lateral dimensions and spacings approximately the same as the lateral dimensions and spacings of said large grains of cadmium sulfide, whereby the lateral grain dimensions in said cadmium sulfide and indium phosphide layers are maximized while the quantity of indium in said solar cell is minimized.

Abstract: A new, useful and nonobvious process is disclosed wherein vapor phase controlled stoichiometry is employed to obtain compound semiconductor films having large crystallite textures. The process has been found to be particularly useful in the formation of compound semiconductor films where one of the components is a high vapor pressure element and the substrate material is amorphous.

Abstract: An apparatus and method for epitaxial film formation is disclosed. Planar reactive evaporation techniques suitable for scaling are employed to produce high purity compound semiconducting films at relatively low temperatures.

Abstract: There is disclosed a silver doped silicon single crystal charge storage photodiode substrate suitable for use in an alternating current driven liquid crystal light valve. The gain capability of the charge storage photodiode makes it possible to construct a single crystal substrate ac light valve very similar in structure to that presently being used with a cadmium sulphide photodiode, but having improved operating characteristics and benefitting from a more fully developed manufacturing technology for silicon devices. One specific embodiment of such a single crystal substrate is a silicon substrate doped with a slow recombination center element such as silver.

Abstract: In a light actuated device such as an alternating current driven light valve or other display device requiring the photocapacitance of a light responsive layer in a photodiode to be modulated in response to changes in incident or writing light, sensitivity is an important factor, especially when a cathode ray tube phosphor image is the source of such light. This sensitivity can be improved by more than an order of magnitude by using a graded defect center (as defined hereinbelow) concentration, graded band gap layer in said diode which can produce a graded optical absorption coefficient between two regions of the layer so that most of the incident light is absorbed in the region near the semiconductor rectifying junction of the diode to store charge near this junction by this or any similar action.