Initial Growth and Crystallization Onset of Plasma Enhanced-Atomic Layer Deposited ZnO

Alberto Perrotta, Julian Pilz, Roland Resel, Oliver Werzer, Anna Maria Coclite

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Direct plasma enhanced-atomic layer deposition (PE-ALD) is adopted for the growth of ZnO on c-Si with native oxide at room temperature. The initial stages of growth both in terms of thickness evolution and crystallization onset are followed ex-situ by a combination of spectroscopic ellipsometry and X-ray based techniques (diffraction, reflectivity, and fluorescence). Differently from the growth mode usually reported for thermal ALD ZnO (i.e., substrate-inhibited island growth), the effect of plasma surface activation resulted in a substrate-enhanced island growth. A transient region of accelerated island formation was found within the first 2 nm of deposition, resulting in the growth of amorphous ZnO as witnessed with grazing incidence X-ray diffraction. After the islands coalesced and a continuous layer formed, the first crystallites were found to grow, starting the layer-by-layer growth mode. High-temperature ALD ZnO layers were also investigated in terms of crystallization onset, showing that layers are amorphous up to a thickness of 3 nm, irrespective of the deposition temperature and growth orientation.
Original languageEnglish
Article number291
JournalCrystals
Volume10
Issue number4
Publication statusPublished - 10 Apr 2020

Fields of Expertise

  • Advanced Materials Science

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