Molecular beam epitaxy of Cu2ZnSnSe4 thin films grown on GaAs(001)

Cu₂ZnSnSe₄ (CZTSe) thin films are grown on GaAs(001) by molecular beam epitaxy in order to produce epitaxial reference material for the characterization of the fundamental physical properties of the semiconductor. The epitaxy is made possible by a new high temperature co-evaporation process which takes into account that CZTSe easily decomposes at the growth temperatures used. The co-evaporation process can easily be transferred to polycrystalline films on molybdenum coated glass substrates for absorbers in solar cells. By using a considerable pressure of SnSe, the decomposition can be avoided. This manuscript describes the growth process and how a specific composition can be grown with high precision. X-Ray diffraction measurements confirm that CZTSe grows epitaxially on GaAs. Raman spectroscopy and Photoluminescence measurements are used to study the occurrence of secondary phases and the quality of the films.