Growth of CuInS2 epitaxial films on Si(001) by multisource evaporation method

CuInS2 thin films were epitaxially grown on Si(001) wafers at 500 degrees C using multisource evaporation method. The Cu source temperature was varied keeping the In and S Source temperatures constant. The obtained films belonged to the Cu2S-ln(2)S(3) system with little extra phase over the range of 0.9 <= [Cu]/[In] <= 2.9. X-ray diffraction and reflection high energy electron diffraction measurements showed that the films were composed of Cu-Au, sphalerite and chalcopyrite structures, although the last was not always observed. The characteristic structures in the photoluminescence spectrum of a film with [Cu]/[In] = 1.4 measured at 23 K was interpreted as the weak broad exciton emission and the donor-acceptor pair emission with a phonon replica comparing to the bulk crystals. The position and the broadening of the exciton emission are reasonable considering the coexistence of various crystal structures.