Atomic scale controlled tunnel oxide enabled by a novel industrial tube‐based PEALD technology with demonstrated commercial TOPCon cell efficiencies > 24%

Abstract

AbstractIn this work, we report on a significant breakthrough in fabricating the critical tunnel oxide layer of tunnel oxide passivated contacts (TOPCon) high‐efficiency solar cells compatible with high‐volume manufacturing. We show that the tunnel oxide can be controlled at the atomic scale, enabled by an innovative tube‐type industrial plasma‐assisted atomic layer deposition (PEALD) method. In combination with an in situ doped poly‐Si (n+) layer grown by plasma‐enhanced chemical vapor deposition, a uniform, ultrathin ~1.3 nm SiOxlayer is obtained at thec‐Si/SiOx/poly‐Si (n+) interface. Extremely low recombination current densities down to 2.8 fA/cm2and an implied open‐circuit voltage (iVoc) as high as 759 mV are achieved, comparable to state‐of‐the‐art laboratory results. The developed tube‐type PEALD SiOxis applied to industrial TOPCon solar cells resulting in a solar cell efficiency and open‐circuit voltage of up to 24.2% and 710 mV, respectively. The tunnel oxide process window is about 2.4 Å, highlighting the importance of precisely controlling the tunnel oxide thickness at the atomic scale for TOPCon solar cells. The newly developed tube‐type industrial PEALD SiOxmethod opens up a promising new route toward mass production of high‐efficiency industrial TOPCon solar cells. Furthermore, the developed tube‐type PEALD method can easily be integrated with the industrial tube‐type plasma‐enhanced chemical vapor deposition (PECVD) method, thus enabling the deposition of all thin film layers in TOPCon solar cells in one integrated PEALD/PECVD system. This significantly simplifies manufacturing complexity and fosters the commercialization of next‐generation high‐efficiency industrial TOPCon solar cells.