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In this work, we report the different effects of CdCl 2 treatment on CdTe films deposited by thermal evaporation onto CdS and MgZnO (MZO) buffer layers. The main finding, which is relevant for understanding recent advances in CdTe device efficiency, is that few-μm thick CdTe films deposited on MZO can be induced to completely recrystallize forming a film consisting of grains that span the film thickness and are up to 30 μm laterally. On CdS buffer layers, the changes in microstructure with Cl treatment are much less pronounced and the final microstructure is less ideal for thin film photovoltaics. We propose a thermodynamic framework for understanding the microstructural changes during CdCl 2 treatment which can assist in understanding the wide range of behaviors observed across the many CdTe thin film solar cell fabrication procedures.
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Water‐Assisted Liftoff of Polycrystalline CdS/CdTe Thin Films Using Heterogeneous Interfacial Engineering
Abstract Recent advances in device design and process optimizations have enabled the production of CdTe devices on flexible substrates, but the necessary high‐temperature processing (>450 °C) to recrystallize grains limits the use of alternative lightweight substrates. Here, a new synthesis method is reported to create a freestanding CdS/CdTe film by combining high‐temperature depositions (CdS/CdTe on Si/SiO2) and a simple lift‐off process in a water environment at room temperature. Analysis of the results indicate that the delamination is facilitated by the innate lattice mismatch as well as the presence of an unexpected Te‐rich layer (≈20 nm), which accumulates on the SiO2surface. High‐resolution electron microscopy and spectroscopy measurements confirm that the CdS/CdTe film is physically liberated from the substrate without leaving any residue, while also preserving their initial structural and compositional properties.
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- Award ID(s):
- 1711885
- PAR ID:
- 10460185
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 6
- Issue:
- 14
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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