ELECTROCHEMICAL METHOD FOR FORMING A SELENIUM-TELLURIUM LAYER IN A PHOTORECEPTOR
Original Publication Date: 1978-Jun-30
Included in the Prior Art Database: 2004-Mar-31
Xerox Disclosure Journal
A method for forming a photoreceptor which includes a photo-generator layer comprising selenium and tellurium wherein the photogenerator layer is formed by electrochemically codepos-iting selenium and tellurium onto a substrate from a solution of their ions in such a way that the relative amounts of selenium and tellurium which are deposited are controlled by their relative concentrations in the electrolyte and by the choice of electrochemical conditions, i.e., current density or electrod-potential. The electrolyte is typicall-fromabout 0.OlM Te and about 0,lM HC1 to a-Q-pt0.0025M Te a-about 0.025M HC1; and from about 0.lM Se to about lOM Se , The conducting substrate may comprise any material which will provide a good blocking contact with selenium alloys such as, for example, gold, platinum, and tin oxide coated glass. Passage of a constant current supplied by a D.C,-nergys-rce through the electrolyte causes reduction of Se and Te to form an amorphous seleniuim-tel]0urium alloy at the c-thode, Typically, an approximately l000A to approximately 3000A thick film of the selenium-tellurium alloy can be4deposi2ted using a currei-t in -he range of from about 1.5 x 10 A/Cm to about 5 x 10 A/Cm for about twenty eight minutes, It is preferred that the tellurium concentration in the layer be from about 5 atomic percent to about 17 atomic percent and optimally about 10 atomic percent. To ensure preferential deposition of selenium during codeposition of selenium and tellurium from the electrolyte it is necessary that the current density and concentration of selenium and tellurium in the electrolyte be selected so that tellurium deposits under limiting current conditions, i.e., the current density for deposition of tellurium is limited by the arrival of tellurium containing ions at the cathode. In this manner, the amount of selenium codepositing on the cathode can be increased at will by increasing the total applied current density and/or the selenium concentration in the electrolyte.