CHARACTERIZATION OF STRUCTURES CRYSTALLIZING IN THE CU2-XS SAMPLES GROWN BY CHEMICAL VAPOR DEPOSITION
The region of the of the copper sulfide region, Cu2-xS (0.05 < x < 0.26), is known to possess many interesting and complicated phases [1-4]. Digenite is one of the common structure types and is based on a cubic close-packing array, crystallizing in the Fm-3m space group with a=5.57A . Several types of ordered digenite superstructures have been reported: 2a, 3a, 4a, 5a and 6a, which are named as multiples of the dimension of the cubic sub-cell .
In Prof. Nessim`s laboratory, novel method was developed for growing layered, crystalline, p-type copper sulfide. It is a one-step synthesis performed by thermal annealing of a standard copper foil in an inert environment using chemical vapor deposition (CVD) .
In the current work, characterization of this material was performed using transmission electron microscopy (TEM). Several structural variants of the basic FCC digenite were found: ordered 6a digenite, basic FCC structure and a primitive cubic structure, which was not reported before. The space group of the later structure evaluated and determined as Pa-3. In addition, the 6a ordered digenite phase`s analysis has revealed an interesting radiation damage affect and twin of modulation.