Surface Passivation Properties of HfO2 Thin Film on n-Type Crystalline Si

Xuemei Cheng, Paivikki Repo, Halvard Haug, Alexander Pyymaki Perros, Erik Stensrud Marstein, Marisa Di Sabatino, Hele Savin

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)

Abstract

Atomic layer deposited hafnium oxide is shown to provide good surface passivation of low resistivity, n-type crystalline Si wafers after a low temperature anneal. The surface passivation is related to a fixed negative charge, as well as an excellent interface with the crystalline Si wafer. In this paper, the influence of four deposition parameters on the HfO2 passivation properties, namely precleaning, precursors, deposition temperature, and postannealing temperature, is discussed. Minority carrier lifetimes of 1.9 ms (surface recombination velocity (SRV) 7.7 cm/s) on float zone n-type wafers and 1.7 ms (SRV 11 cm/s) on Czochralski n-type wafers, under optimized deposition conditions and a postannealing process, have been measured. A significant improvement of the surface passivation is observed after 100 h light soaking, resulting in a carrier lifetime of 2.5 ms. Fitting of the results by a two-defect charge trapping/detrapping model indicates that additional light-induced negative charges enhance the field effect passivation, which is also consistent with the experimental results. Due to its high refractive index and the obtained good surface passivation of Si wafers, HfO2 has a great potential as a surface passivation material, e.g., in the fabrication of high-efficiency Si solar cells.

Original languageEnglish
Article number7812606
Pages (from-to)479-485
Number of pages7
JournalIEEE Journal of Photovoltaics
Volume7
Issue number2
DOIs
Publication statusPublished - 1 Mar 2017
MoE publication typeA1 Journal article-refereed

Keywords

  • Atomic layer deposition (ALD)
  • defect density
  • fixed charges
  • hafnium oxide (HfO)
  • photovoltaic cells
  • silicon surface passivation

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