CuIn(1−x)GaxSe2 Recrystallization by Metal Halide Treatments

CuIn (1−x) Ga x Se 2 (CIGS) photovoltaics have limited market success due to high capital costs largely attributed to a slow, high-temperature deposition procedure. To reduce such costs we show that a high-rate, low-temperature approach including a short recrystallization step using metal halides can dramatically increase grain size in CIGS. We have demonstrated this both with high-rate evaporated films and amorphous films sputtered at room temperature. Both approaches can greatly increase throughput and reduce the costs of CIGS deposition. We review previous results for a number of metal halides and specifically focus on InCl 3 and AgBr as the most promising. We show that using high-temperature x-ray diffraction that crystallization begins at 270°C and ends at 380°C and is greatly accelerated by the metal halides, resulting in much larger grains over the same temperature range.