Apparatus for continuously producing tandem amorphous photovoltaic cells

Abstract

A method and a multiple chamber apparatus for the continuous production of tandem, amorphous, photovoltaic solar cells on substrate material, whereby, at least six amorphous layers are continuously and sequentially deposited on the substrate material under steady conditions. The substrate material is driven from a supply core, through at least two triads of deposition chambers, to a take-up core. Each amorphous layer of each p-i-n-type cell is produced in one chamber of the triad of deposition chambers. In the first chamber of each triad of chambers, dopant gases are introduced to deposit a first conductive layer. In the second chamber of each triad of chambers, reaction gases are introduced to deposit an intrinsic layer atop the first layer. And in the third chamber of each triad of chambers, dopant gases are introduced to deposit a second conductive layer, opposite in conductivity from the first conductive layer, atop the intrinsic layer. The multiple chamber apparatus is constructed to substantially prevent (1) the dopant gases in the first or third chamber from contaminating the intrinsic reaction gases in the second chamber of each triad of deposition chambers; and (2) the dopant gases in the third chamber of one triad of deposition chambers and the dopant gases in the first chamber of an adjacent triad of deposition chambers from cross-contamination. In the preferred embodiment, the intrinsic material is an amorphous silicon alloy which is doped by boron to form a p-type alloy and doped by phosphorous to form an n-type alloy. The preferred embodiment further contemplates the use of a glow discharge deposition process wherein vacuum pressure conditions, temperature levels, reaction gas mixtures, reaction gas flow rates, cathode power generation levels, and substrate speed of travel are precisely controlled.