Improving the crystallinity of quaternary sputtered CIGS absorber layer properties via optimized deposition and annealing temperature

This study presents a method to improve Cu(In_1−xGa_x)Se₂ (CIGS) absorber layer performance through an annealing technique that enhances the quality of as-deposited CIGS films. CIGS films were deposited on soda-lime glass substrates using RF magnetron sputtering at 300 °C, 400 °C, and 500 °C, followed by annealing at 500 °C for 30 min. By annealing, the crystal structure of the CIGS films is aligned, and surface strain is minimized. It can significantly boost the films’ crystallinity, crystallite sizes, carrier concentration, mobility, and energy gap. The highest temperatures enhanced crystallinity due to larger crystallite size, resulting in lower resistivity. The properties improvements are crucial for optimizing CIGS absorber layer performance. Complete CIGS solar cell at 300 °C yield V_oc = 253 mV, J_sc = 1.78 mA/cm², and efficiency = 0.15 %.