Abstract:
A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S). sub. 2 comprises depositing a first layer of (In,Ga). sub. x (Se,S). sub. y followed by depositing just enough Cu+(Se,S) or Cu. sub. x (Se,S) to produce the desired slightly Cu-poor material. In a variation, most, but not all, (about 90 to 99%) of the (In,Ga). sub. x (Se,S). sub. y is deposited first, followed by deposition of all the Cu+(Se,S) or Cu. sub. x (Se,S) to go near stoichiometric, possibly or even preferably slightly Cu-rich, and then in turn followed by deposition of the remainder (about 1 to 10%) of the (In,Ga). sub. x (Se,S). sub. y to end with a slightly Cu-poor composition. In yet another variation, a small portion (about 1 to 10%) of the (In,Ga). sub. x (Se,S). sub. y is first deposited as a seed layer, followed by deposition of all of the Cu+(Se,S) or Cu. sub. x (Se,S) to make a very Cu-rich mixture, and then followed deposition of the remainder of the (In,Ga). sub. x (Se,S). sub.