Ion Backscattering Study of Cu2 S  Formation on Single Crystal CdS

Abstract

Ion backscattering has been used to study the formation of Cu2S layers on single crystal normalCdS due to the chemical ion exchange reaction2Cu++normalCdS→Cu2S+Cd++The reaction is found to proceed most rapidly on the A (Cd) face, slower on the B (S) face, with the reaction proceeding slowest on faces perpendicular to the <112̅0> axis. Reactions on the A and B faces are characterized by a very nonuniform Cu2S‐normalCdS interface, whereas the interface for reactions along the <112̅0> is much more uniform. The reaction in the latter case may be controlled by surface nucleation, and layer formation subsequent to formation of a 300–500Å thick layer is much slower. The formation of Cu2S on the A and B faces has an activation energy of 0.9–1.5 eV. Preparation of the surface by polishing leads to a larger rate of Cu2S formation and Cu2S‐normalCdS interfaces which are more uniform as a function of depth than those in etched samples.

A Transmission Electron Microscope Study of the Chalcocite–Djurleite Transformation in Topotactically Grown Thin Films of CuxS

“…I n contrast the work described here has investigated both, as well as changes brought about by oxidation. The Cu,S was produced on the (1120) face of single crystals of CdS because this plane produces the most uniform layer [16]. The solid state transforniation was used because it is a quantitative reaction that goes to completion and produces more a honiogeneous Cu,S layer than the wet dip process [lo, 171.…”