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Lecture

Oxide semiconductors and devices produced by magnetron sputtering and selective area atomic layer deposition methods



Transparent electrodes take part in many functional applications such as low emissivity coatings, flat panel displays and particularly solar cells which is the application envisaged in this work. Textured surfaces combined with the properties of transparent electrodes can amount to great results; for example, textured cells deliver more photocurrent than planar cells [1] and are less affected by the deterioration of material properties over time thanks to their very large specific surface. The photocurrent to be delivered is highly dependent on the thickness of the films as well as the periodicity and depth of the structure. Zinc oxide (ZnO) and Al-doped ZnO (AZO) are widely used as n-type semiconductors and transparent electrodes. High Impulse Magnetron Sputtering (HiPIMS) allows depositing highly conductive and transparent films on large surfaces and at low temperatures [2]. The AZO films thus obtained using HiPIMS are submitted to electrical (Four-point probe, Hall effect), optical (UV-Vis), morphological (TEM), chemical (EDS, EELS) and structural (XRD) characterization methods. Atomic Layer Deposition (ALD) is used for depositing high-quality films with excellent surface coverage and conformal deposition; this method enables us to combine metallic Cu films with semiconductor oxides (ZnO, Cu2O, or both) leading to many applications in different fields related with optoelectronics, catalysis, and photovoltaics [3]. Cuprous oxide (Cu2O) is a direct-gap semiconductor also used as an absorber in solar cells. The fabrication of segmented p-Cu2O/n-ZnO nano-junctions is facilitated by selected area ALD (SA-ALD). In this presentation, we report on the optimization of AZO layers synthesized by reactive HiPIMS [2], on the fabrication of devices based on p-Cu2O/n-ZnO nano-junctions by a combination of HiPIMS and a SA-ALD method we have developed [3] and on the strategy we are developing, towards the fabrication of segmented textured solar cells based on such junctions.


[1] M. Soldera et al., Physica status solidi (a), vol. 210, no 7, p. 1345‑1352, 2013.

[2] M. Mickan et al., Solar Energy Materials and Solar Cells, vol. 157, p. 742-749, 2016.

[3] C. de Melo et al., ACS Applied Materials & Interfaces, vol. 10, no 43, p. 37671-37678, 2018.

 

Speaker:
Ph.D. Christy Fadel
University of Lorraine
Additional Authors:
  • Dr. Stéphane Cuynet
    University of Lorraine
  • Dr. Claudia de Melo
    University of Lorraine
  • Dr. Marcos Soldera
    Technische Universität Dresden
  • Prof. Dr. Jean-François Pierson
    University of Lorraine
  • Prof. Dr. Frank Müklich
    Universität des Saarlandes
  • Prof. Dr. David Horwat
    University of Lorraine