Influence of substrate temperature on properties of pyrite thin films deposited using a sequential coevaporation technique

Highlights: • A sequential vapor deposition method produced high–quality, pyrite thin films • Films deposited at >400 °C exhibit ideal stoichiometry and ~100% phase purity. • Film grown at 420 °C have columnar grains with pyrite (100)||(100) Si substrate. -- Abstract: A series of pyrite thin films were deposited in-situ in a monolayer-by-monolayer fashion using sequential evaporation of iron under high vacuum, followed by sulfidation at a sulfur pressure of 133 Pa, as a function of substrate temperature. The stoichiometry, crystallinity, topographic smoothness, and phase purity of the deposited pyrite thin films improve with increasing substrate temperature up to 420 °C, the highest temperature studied. Characterization of the films deposited at 420 °C using selected-area precession electron diffraction, Raman Spectroscopy, and conventional X-ray diffraction indicated that the pyrite layer is phase pure, with no evidence of a secondary marcasite phase, and grew in columnar grains with a preferential (100) orientation on the (100) silicon substrates. This novel sequential evaporation technique has the potential to make useful low-cost semiconducting pyrite materials for large-area electronic applications.