CHEMICAL BATH DEPOSITION OF CUBIC COPPER(I) SELENIDE AND ITS ROOM-TEMPERATURE TRANSFORMATION TO THE ORTHORHOMBIC PHASE

The chemical bath deposition of cubic copper (I) selenide (Cu2-xSe) th in films has been achieved on an inert Pt substrate from a selenosulfi te-containing bath at 75 degrees C. The electrochemical polarisation o f this film at -0.78 V vs. SCE leads to the transformation of the comp ound into the orthorhombic phase. The lattice parameter of the face-ce ntered cubic copper (I) selenide increases from 5.742 Angstrom to 5.76 1 Angstrom due to the decrease of the concentration of Cu vacancies up on electrochemical polarisation. The transformation of the cubic to an orthorhombic phase starts to occur when copper vacancies reach a crit ical value of x < 0.15. This transformation seems to be induced by a C u3Se2 impurity in the cubic Cu2-xSe phase. (C) 1997 Elsevier Science S .A.