Asymmetric growth on the polar surfaces of CdS ribbons

Cadmium sulfur ribbons were produced on an Au-coated Si substrate by chemical vapor deposition of CdS powder. The growth direction of the ribbons was [011¯0]. Asymmetric growth had occurred on the ±(0 0 0 1) planes. Two types of ribbons were found. In one type, saw-tooth structure was rooted on the active Cd-terminated (0 0 0 1) surface while the inert S-terminated (0001¯) surface remained flat. In the second type, finer finger/saw-tooth pairs were found on one side, nano-finger-like structure was on the other. The nano-fingers were grown on some high-energy planes between the S-terminated (0001¯) plane and the ±(21¯1¯0) facets. This lateral asymmetric growth behavior was due to surface polarization.