Recrystallization method to selenization of thin-film Cu(In,Ga)Se2 for semiconductor device applications

Abstract

Abstract A process for fabricating slightly Cu-poor thin-films of Cu(In,Ga)Se 2 on a substrate for semiconductor device applications includes the steps of forming initially a slightly Cu-rich, phase separated, mixture of Cu(In,Ga)Se 2 :Cu x Se on the substrate in solid form followed by exposure of the Cu(In,Ga)Se 2 :Cu x Se solid mixture to an overpressure of Se vapor and (In,Ga) vapor for deposition on the Cu(In,Ga)Se 2 :Cu x Se solid mixture while simultaneously increasing the temperature of the solid mixture toward a recrystallization temperature (about 550° C.) at which Cu(In,Ga)Se 2 is solid and Cu x Se is liquid. The (In,Ga) flux is terminated while the Se overpressure flux and the recrystallization temperature are maintained to recrystallize the Cu x Se with the (In, Ga) that was deposited during the temperature transition and with the Se vapor to form the thin-film of slightly Cu-poor Cu x (In,Ga) y Se z . The initial Cu-rich, phase separated large grain mixture of Cu(In,Ga)Se 2 :Cu x Se can be made by sequentially depositing or co-depositing the metal precursors, Cu and (In, Ga), on the substrate at room temperature, ramping up the thin-film temperature in the presence of Se overpressure to a moderate anneal temperature (about 450° C.) and holding that temperature and the Se overpressure for an annealing period. A nonselenizing, low temperature anneal at about 100° C. can also be used to homogenize the precursors on the substrates before the selenizing, moderate temperature anneal.

Inventors

• 👤 David S. Albin
• 👤 Jeffrey J. Carapella
• 👤 John R. Tuttle
• 👤 Miguel A. Contreras
• 👤 Andrew M. Gabor
• 👤 Rommel Noufi
• 👤 Andrew L. Tennant

Bibliographic Details