Passivation quality and contact resistance of tunnel nitride passivated contacts with various silicon nitride compositions

Abstract We have recently developed tunnel nitride passivation contacts (TNPCon) by replacing the passivation layer in tunnel oxide passivation contacts solar cells with silicon nitride (SiN x ) deposited by catalytic chemical vapor deposition. This paper reports on the performance of TNPCon structures when the composition of SiN x is systematically varied in order to improve the passivation performance. We successfully deposited SiN x films with different compositions by varying the flow rate of SiH 4 gas used for deposition. We investigated their passivation performance and revealed that N-rich films exhibit better passivation quality. On the other hand, Si-rich films exhibit lower contact resistivity and sufficient tunneling contact can be realized in thicker films. We thus revealed that the trends in composition are inversely related between passivation performance and electrical conductivity.