Plating baths and methods for electroplating selenium and selenium alloys

Abstract

Plating bath solutions and methods for depositing selenium generally include an aqueous plating bath containing a soluble selenium source and a soluble surfactant additive, wherein the soluble surfactant additive is selected from the group consisting of an alkane sulfonic acid, an alkane phosphonic acid and mixtures thereof, wherein the alkane group defining the alkane sulfonic acid and the alkane phosphonic acid has less than 25 carbon atoms The method includes immersing a conductive substrate to be plated into the aqueous plating bath; and electroplating selenium onto the substrate to form a continuous and particle free film.

What is claimed is: 
     
         1 . A method of electroplating selenium onto a conductive substrate, the method comprising:
 immersing a conductive substrate to be plated into an aqueous plating bath at a pH of 2 to 4 containing a soluble selenium source and a soluble surfactant additive, wherein the soluble surfactant additive is selected from the group consisting of an alkane sulfonic acid, an alkane phosphonic acid and mixtures thereof, wherein the alkane group defining the alkane sulfonic acid and the alkane phosphonic acid has less than 25 carbon atoms; and   electroplating selenium onto the substrate to form a continuous and particle free film.   
     
     
         2 . The method of  claim 1 , wherein the conductive substrate includes a surface comprising copper or indium or gallium or mixtures thereof. 
     
     
         3 . The method of  claim 1 , wherein the aqueous plating bath is at a temperature of about 15° C. to about 45° C. 
     
     
         4 . The method of  claim 1 , wherein the aqueous plating bath is at a pH of about 3 to 4. 
     
     
         5 . The method of  claim 1 , wherein electroplating selenium onto the substrate is at a current density of about 0.5 to about 20 mA/cm 2 . 
     
     
         6 . The method of  claim 1 , wherein electroplating selenium onto the substrate is at a current density of about 1 to about 10 mA/cm 2 . 
     
     
         7 . The method of  claim 1 , wherein the surfactant additive is at a concentration of about 1 milligram to about 1 gram per liter. 
     
     
         8 . The method of  claim 1 , wherein the surfactant additive is at a concentration of about 5 milligrams per liter to about 750 milligrams per liter. 
     
     
         9 . The method of  claim 1 , wherein the surfactant additive is at a concentration of about 10 milligrams per liter to about 250 milligrams per liter. 
     
     
         10 . The method of  claim 1 , wherein the selenium compound is at a concentration of about 0.001 M to about 1 M. 
     
     
         11 . The method of  claim 1 , wherein the selenium compound is at a concentration in an amount of about 0.01 M to about 1 M. 
     
     
         12 . The method of  claim 1 , wherein the selenium compound is at a concentration in an amount of about 0.1 M to about 1 M. 
     
     
         13 . The method of  claim 1 , wherein the electroplated selenium is amorphous and is free of particles. 
     
     
         14 . The method of  claim 1 , wherein the selenium source comprises a selenium source dissolved in one of sulfuric acid, nitric acid, and hydrochloric acid. 
     
     
         15 . The method of  claim 1 , further comprising copper ions or indium ions or gallium ions or mixtures thereof in the aqueous plating bath. 
     
     
         16 . A method of electroplating selenium onto a conductive substrate, the method comprising:
 providing an aqueous plating bath containing a soluble selenium source and a soluble surfactant additive, wherein the soluble surfactant additive is selected from the group consisting of an alkane sulfonic acid, an alkane phosphonic acid and mixtures thereof, wherein the alkane group defining the alkane sulfonic acid and the alkane phosphonic acid has less than 25 carbon atoms, wherein the aqueous plating bath has a pH in the range of 2 to 4 and is at a temperature in the range of 18° C. to 25° C.;   contacting the aqueous plating bath with the conductive substrate and the anode;   establishing a potential difference between the anode and the conductive substrate; and   electroplating selenium onto the conductive substrate at a current density in the range of 0.5 to 20 mA/cm 2  to form a continuous and particle free film.   
     
     
         17 . The method of  claim 16 , wherein the aqueous plating bath further comprises copper ions or indium ions or gallium ions or mixtures thereof. 
     
     
         18 . The method of  claim 16 , wherein the wherein the alkane group defining the alkane sulfonic acid and the alkane phosphonic acid has less than 12 carbon atoms. 
     
     
         19 . The method of  claim 16 , wherein the conductive substrate includes a surface comprising copper or indium or gallium or mixtures thereof 
     
     
         20 . The method of  claim 16 , wherein the selenium compound is at a concentration of about 0.001 M to about 1M and wherein the surfactant additive is at a concentration of about 1 milligrams per liter to 1000 milligrams per liter.