ABSTRACT
This chapter describes the surface passivation materials and techniques to improve the performance of passivated emitter and rear contact (PERC) solar cells, which are the currently mainstream product in the photovoltaic market. First, this chapter discusses the key parameters and performances of PERC solar cells, when compared with those of the conventional silicon solar cells. As passivation layers prepared by atomic layer deposition (ALD) show the best passivation quality among other deposition techniques, this chapter reviews main ALD processes—including spatial, thermal and plasma—and discusses the mechanism and fabrication of the ALD passivation thin films such as aluminum oxide (Al2O3) and hafnium oxide (HfO2) in terms of field-effect passivation and chemical passivation. In addition, post-annealing process strongly affects the crystalline and electrical properties of the passivation thin films and interface oxides. An advanced annealing process is developed for obtaining a high wafer lifetime, high fixed oxide charge, and a low interface defect density. Finally, this chapter presents the performance of PERC solar cells with optimized Al2O3 and HfO2 passivation layers.
