a1 Materials and Molecular Research Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720
The growth of CU2-xS in the (0001) basal face of single crystal cadmium sulfide has been studied with high resolution transmission electron microscopy (HRTEM) and diffraction. Cross-sectional Cu2-xS/CdS specimens and plan-view Cu2-xS separated films were prepared from heterojunctions formed by the aqueous conversion of CdS to topotaxial Cu2-xS. Low chalcocite films were found to form in two principal stages; 1) coalescence of low chalcocite islands and 2) an accelerated reaction localized at pores in the Cu2-xS film. Several possible misfit accommodation mechanisms involving twinning, cracking, and a second copper sulfide phase were identified.