Crystal quality,electrical and optical properties of single crystal pyrite films prepared by chemical vapor deposition under atmospheric pressure

Crystal quality, electrical and optical properties of single crystal thin films of pyrite prepared by means of chemical vapor deposition under atmospheric pressure (AP-CVD) using FeCl₃ and CH₃CSNH₂ as starting materials have been studied by various analytical method. X-ray diffraction and pole figure measurements showed that the as-grown films are single crystal. It was found that the quality of the pyrite films grown on a Si(100) substrate is significantly dependent upon the ratio of CH₃CSNH₂:FeCl₃ used as source materials. Electrical conductivity and Hall mobility increases as the CH₃CSNH₂:FeCl₃ ratio is increased, while carrier concentration decreases. This is explained in term of the formation of sulphur vacancies. A decrease of the CH₃CSNH₂:FeCl₃ ratio causes the increase of sulphur defects in the pyrite film. This also increases the number of electrons being trapped by the defects, while their mobility is reduced because of the electron being scattering at the vacancies. Strong absorption occurs in the photon energy range higher than 1 eV, and then reaches plateau with an absorption coefficient of about $5\times {10}^4{\text{cm}}^{-1}$ at $E>2\text{eV}$.