Formation of CuPt-type ordered (Cd, Zn)Te at CdTe/ZnTe interface

Abstract

A CuPt-type ordered CdZnTe has been observed at CdTe/ZnTe interface sequentially grown by organometallic vapor-phase epitaxy on (001)GaAs at 400 degrees C. Selected area electron diffraction, cross-sectional high-resolution electron microscopy, and computer image simulation have been employed to characterize the ordered structure in CdZnTe. Between CdTe and ZnTe, we observed a relatively uniform layer with dark contrast band image by conventional transmission electron microscopy. Through [110] projection, selected area electron diffraction pattern showed two sets of (1/2 1/2 1/2) extra spots with symmetrical intensity and corresponding high-resolution images showed doubling periodicity in contrast on {111} lattice planes. The ordered structure has been identified as CuPt-type ordered CdZnTe from electron diffraction, high-resolution images, and computer image calculations. Through [110] projection, it was observed that there were two variants for ordering according to each direction of doubling periodicity on {111} lattices planes, i.e., on (1(1) over bar 1) and on (<(1)over bar 11>). Each variant was observed to have its own domain structure of which size ranged from 10 to 20 nm and the two variants were observed with equal probability. (C) 1998 Elsevier Science B.V. All rights reserved.