Author:

Abstract:

In this study, thermal atomic layer deposition (ALD) of Al2O3 is (1) first characterized as surface passivation layer for p-type CZ Si and (2) accordingly implemented into industrial large-area “passivated emitter and rear cell” (PERC) p-type Si solar cells. (1) The characterization part is focused on relevant topics for Si solar cell processing: the development of an adequate pre-passivation wafer clean and an in depth study of the impact of thermal treatments on (i) Al2O3 passivation characteristics - chemical and field effect passivation - and (ii) Al2O3 material characteristics - crystallization and blistering. (2) As rear surface passivation for industrial large-area p-type Si PERC, a blister-free stack of Al2O3(≤ 10 nm)/(SiOx/)SiNx is employed, leading to optimal rear surface passivation and back reflection. An average cell conversion efficiency of 19.4 % has been obtained, as independently confirmed by FhG-ISE CalLab. The illumination independency, an important advantage of Al2O3 rear passivated p-type Si PERC, is discussed in detail. Two alternative approaches to implement Al2O3 layers in Si solar cell processing are proposed as well: Al2O3-based emitter passivation and rear contacting induced by blistered Al2O3 passivation layers.