Investigation on self-aligned HgTe nano-crystals induced by controlled precipitation in PbTe-HgTe quasi-binary compound semiconductor alloys

The present paper reports the results of the controlled precipitation for t he HgTe nano-crystals in the PbTe semiconductor matrix and demonstrates its effectiveness in producing well-organized and crystallographically aligned semiconductor nano-crystals. Following the same procedure used in metallic alloys, the semiconductor alloys are treated at 600 degreesC for 48 h, que nched and aged up to 400 h at 300 degreesC and 400 degreesC to induce homog eneous nucleation and growth of HgTe precipitates. Examination of the resul ting precipitates using transmission electron microscopy (TEM) reveals that the coherent HgTe precipitates form as thin disks along the {1 0 0} habit planes of PbTe matrix. It is also found that the precipitate undergoes a gr adual shape change without any noticeable coarsening, from a disk to a cube , as the aging time increases. The microstructure after full aging is found to contain almost equal sized HgTe cubes, roughly 7 nm, that maintain cohe rency with {1 0 0} planes of the matrix. These results combined with the ex treme dimension of the precipitates and the simplicity of the formation pro cess leads to a belief that controlled precipitation can be an effective me thod in preparing a desirable quantum-dot microstructure. (C) 2001 Elsevier Science B.V. All rights reserved.