Surface passivation of germanium by atomic layer deposited Al2O3 nanolayers

Willem-Jan H. Berghuis (Corresponding author), Jimmy Melskens, Bart Macco, R.J. Theeuwes, Marcel A. Verheijen, W.M.M. Kessels (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)


Surfaces of semiconductors are notorious for the presence of electronic defects such that passivation approaches are required for optimal performance of (opto)electronic devices. For Ge, thin films of Al2O3 prepared by atomic layer deposition (ALD) can induce surface passivation; however, no extensive study on the effect of the Al2O3
process parameters has been reported. In this work we have investigated the influence of the Al2O3 thickness (1–44 nm), substrate temperature (50–350 °C), and post-deposition anneal (in N2, up to 600 °C). We demonstrated that an effective surface recombination velocity as low as 170 cm s−1 can be achieved. The role of the GeOx interlayer as well as the presence of interface charges
was addressed and a fixed charge density Qf = −(1.8 ± 0.5) × 1012 cm−2 has been found. The similarities and differences between the passivation of Ge and Si surfaces by ALD Al2O3 prepared under the same conditions are discussed.
Original languageEnglish
Pages (from-to)571-581
Number of pages11
JournalJournal of Materials Research
Issue number3
Early online date28 Jan 2021
Publication statusPublished - Feb 2021


  • Al O
  • Aluminium oxide
  • Atomic layer deposition
  • Fixed charge density
  • Germanium
  • Surface passivation


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