Spatially-separated atomic layer deposition of Al2O3, a new option for high-throughput Si solar cell passivation

B. Vermang, F. Werner, W. Stals, A. Lorenz, A. Rothschild, J. John, J. Poortmans, R. Mertens, R. Gortzen, P. Poodt, F. Roozeboom, J. Schmidt

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

1 Citation (Scopus)

Abstract

A next generation material for Si surface passivation is atomic layer deposited (ALD) Al 2O 3. However, conventional time-resolved ALD is limited by its low deposition rate. Initially, a high-deposition-rate prototype ALD reactor based on the spatially-separated ALD principle has been developed, with Al 2O 3 deposition rates up to 1.2 nm/s. Later, the spatial ALD technique has been transferred to an actual in-line process development tool (PDT) for commercial high-throughput ALD of Al 2O 3, resulting in a deposition rate of 30 nm/min. The passivation quality and uniformity of the spatially-separated ALD Al 2O 3 films are evaluated on p- and n-type Si, applying quasi-steady-state photo-conductance, carrier density imaging and infrared lifetime mapping. In all cases, a spatial ALD Al 2O 3 layer of only 10 nm reached an excellent passivation quality and uniformity, comparable to reference wafers passivated by equivalent temporal plasma-assisted or thermal ALD Al 2O 3. Effective surface recombination velocities as low as 1.1 or 2.9 cm/s were obtained after annealing at 350°C or firing, respectively. Using spatial ALD Al 2O 3 passivated local Al back surface field p-type Si solar cells, the sufficient passivation of this high-throughput Al 2O 3 layer is evaluated: an average gain in open circuit voltage as compared to SiO x rear passivated i-PERC cells is obtained.

Original languageEnglish
Title of host publication37th IEEE Photovoltaic Specialists Conference, PVSC 2011
Place of PublicationPiscataway
PublisherInstitute of Electrical and Electronics Engineers
Pages1144-1149
Number of pages6
ISBN (Print)9781424499656
DOIs
Publication statusPublished - 1 Dec 2011
Externally publishedYes
Event37th IEEE Photovoltaic Specialists Conference (PVSC 2011) - Seattle, United States
Duration: 19 Jun 201124 Jun 2011
Conference number: 37

Conference

Conference37th IEEE Photovoltaic Specialists Conference (PVSC 2011)
Abbreviated titlePVSC 2011
CountryUnited States
CitySeattle
Period19/06/1124/06/11

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