Finite element simulation and experimental research on ZnO:Al by magnetron sputtering

Aluminum doped zinc oxide (ZnO:Al) thin films are suitable for the use as transparent conductive electrode in copper indium gallium selenide Cu(In,Ga)Se2 thin film solar cells. The resistivity and film quality of ZnO:Al deposited on soda lime glass is nonuniform in magnetron sputtering process. According to the measurement results of magnetic field on the top of the target, obvious magnetic field distribution nonuniformity is observed along the vertical and horizontal directions respectively. With the longer distance between target and substrate, the magnetic field intensity becomes lower and flatter between the two magnet poles. Based on the simulation results by finite element analysis, it is verified the nonuniformity of magnetic field distribution influences the probability of Ar+ particles collision and the deposition of zinc oxide (ZnO) particles in different regions on substrate. The higher resistivity of ZnO:Al films is obtained where the magnetic field intensity is stronger.