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 the 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, quenched and aged up to 400 h at 300 degreesC and 400 degreesC to induce homogeneous nucleation and growth of HgTe precipitates. Examination of the resulting 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 gradual 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 coherency with {1 0 0} planes of the matrix. These results combined with the extreme dimension of the precipitates and the simplicity of the formation process leads to a belief that controlled precipitation can be an effective method in preparing a desirable quantum-dot microstructure. (C) 2001 Elsevier Science B.V. All rights reserved.