Silicon surface passivation by ultrathin Al₂O₃ films and Al₂O₃/SiN_x stacks

authored by

Jan Schmidt, Boris Veith, Florian Werner, Dimitri Zielke, Rolf Brendel

Abstract

We show that aluminum oxide (Al₂O₃) layers deposited by thermal as well as by plasma-assisted atomic layer deposition (ALD) are very well suited for the effective surface passivation of p-type silicon wafers. Surface recombination velocities (SRVs) well below 10 cm/s are measured for both ALD variants. The SRV strongly increases with decreasing film thickness if the Al₂O₃ films are <10 nm for thermal ALD and <5 nm for plasma ALD. Firing at 830°C in a conveyor-belt furnace deteriorates the passivation quality, in particular for ultrathin Al₂O₃ films. For Al₂O₃ films ≤10 nm the thermal stability of the Al₂O₃ was significantly improved by depositing a 75-nm capping layer of PECVD-SiN_x onto the Al₂O₃. Application of Al₂O₃ to the rear of PERC solar cells shows that high V_oc values above 660 mV and J_sc values of 40 mA/cm² are achievable, irrespective of the ALD variant applied. However, generally slightly higher efficiencies are obtained for Al ₂O₃ deposited by plasma ALD. The plasma ALD layers result in the highest efficiency of 21.1%.

External Organisation(s)

Institute for Solar Energy Research (ISFH)

Type

Conference contribution

Pages

885-890

No. of pages

6

Publication date

2010

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Control and Systems Engineering, Industrial and Manufacturing Engineering, Electrical and Electronic Engineering

Electronic version(s)

https://doi.org/10.1109/PVSC.2010.5614132 (Access: Closed)