Korzun, B.; Rusu, M.; Dittrich, T.; Galyas, A.; Gavrilenko, A.: Optical Properties of Thin Films of Haycockite. MRS Advances 4. (2019), p. 2023-2033
10.1557/adv.2019.273

Abstract:
Thin films of haycockite Cu4Fe5S8 on glass substrates were deposited by flash evaporation technique from powders of this compound. The composition of thin films correspond to the atomic content of Cu, Fe, and S of 24.13, 27.90, and 47.97 at.% with the Cu/ Fe and S/ (Cu + Fe) atomic ratios of 0.87 and 0.92 respectively, whereas the corresponding theoretical values for this material amount to 0.80 and 0.89. The as-prepared thin films of haycockite consist of a set of separate fractions of approximately identical areas of about 400 - 600 µm2. It can be assumed that this structure evolved during cooling down of thin films since it completely covers the surface of thin films. A small inclusion of a second phase with the chemical composition close to talnakhite Cu9Fe8S16 is also observed. Haycockite Cu4Fe5S8 is found to be a direct gap semiconductor with the energy band gap Eg equal to 1.26 eV as determined using both transmission and surface photovoltage methods.