DFG Research Unit 2857

Copper Iodide as Multifunctional Semiconductor

P01: Microstructure-Based Optimization of CuI Thin-Film Growth

Prof. Dr. Michael Lorenz, Dr. Susanne Selle

In this project, the growth of crystalline copper iodide (CuI) based thin films (at U Leipzig) and their microand nanostructural characterization (at Fraunhofer IMWS Halle) are combined. The epitaxial growth of CuI is a critical challenge for the fabrication of high-quality p-n junctions, and CuI-related electronic devices. In our previous work, we achieved first results on highly crystalline, epitaxial CuI thin films with state-ofthe- art performance. The aim now is a microstructure-based material design, in order to control the crystallinity and the functionality of CuI thin films on various substrates. In close interaction of both thin film deposition and microstructure analysis, the characterization of structural defects, of orientation relationships, and of nanomechanical and chemical parameters shall yield a coherent understanding of growth and film functionality. Analytical high-resolution transmission electron microscopy (TEM) is envisaged as one of the main characterization techniques. For that, artifact-free TEM sample preparation approaches have to be evaluated. A related task is the reduction of surface roughness of the CuI films, and their controlled doping and alloying. This project shall contribute to the overall aim of the Research Unit, to extend the application potential of semiconducting CuI-based thin films.