BSTS synthesis guided by CALPHAD approach for phase equilibria and process optimization

Husain F Alnaser; Taylor D Sparks

doi:10.1038/s41598-023-30976-3

BSTS synthesis guided by CALPHAD approach for phase equilibria and process optimization

Sci Rep. 2023 Mar 9;13(1):3944. doi: 10.1038/s41598-023-30976-3.

Authors

Husain F Alnaser¹, Taylor D Sparks^{2

3}

Affiliations

¹ Department of Material Science and Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
² Department of Material Science and Engineering, University of Utah, Salt Lake City, UT, 84112, USA. sparks@eng.utah.edu.
³ Chemistry Department, University of Liverpool, Liverpool, United Kingdom. sparks@eng.utah.edu.

Abstract

This work presents a new method for processing single-crystal semiconductors designed by a computational method to lower the process temperature. This research study is based on a CALPHAD approach (ThermoCalc) to theoretically design processing parameters by utilizing theoretical phase diagrams. The targeted material composition consists of Bi-Se₂-Te-Sb (BSTS). The semiconductor alloy contains three phases, hexagonal, rhombohedral-1, and rhombohedral-2 crystal structures, that are presented in the phase field of the theoretical pseudo-binary phase diagram. The semiconductor is also evaluated by applying Hume-Rothery rules along with the CALPHAD approach. Thermodynamic modelling suggests that single-crystals of BSTS can be grown at significantly lower temperatures and this is experimentally validated by low-temperature growth of single crystalline samples followed by exfoliation, compositional analysis, and diffraction.

Abstract

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