The role of stoichiometric vacancy periodicity in pressure-induced amorphization of the Ga{sub 2}SeTe{sub 2} semiconductor alloy

• Published in: Applied physics letters 2014-08, Vol.105 (5)
• Main Authors: Abdul-Jabbar, N. M., Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Kalkan, B., MacDowell, A. A., Huang, G.-Y., Gronsky, R., Bourret-Courchesne, E. D., Wirth, B. D., Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996
• Format: Article
• Language: English
• Subjects: AMORPHOUS STATE; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL LATTICES; GALLIUM COMPOUNDS; PERIODICITY; SELENIUM COMPOUNDS; SEMICONDUCTOR MATERIALS; STOICHIOMETRY; TELLURIUM COMPOUNDS; VACANCIES
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4892549

We observe that pressure-induced amorphization of Ga{sub 2}SeTe{sub 2} (a III-VI semiconductor) is directly influenced by the periodicity of its intrinsic defect structures. Specimens with periodic and semi-periodic two-dimensional vacancy structures become amorphous around 10–11 GPa in contrast to those with aperiodic structures, which amorphize around 7–8 GPa. The result is an instance of altering material phase-change properties via rearrangement of stoichiometric vacancies as opposed to adjusting their concentrations. Based on our experimental findings, we posit that periodic two-dimensional vacancy structures in Ga{sub 2}SeTe{sub 2} provide an energetically preferred crystal lattice that is less prone to collapse under applied pressure. This is corroborated through first-principles electronic structure calculations, which demonstrate that the energy stability of III-VI structures under hydrostatic pressure is highly dependent on the configuration of intrinsic vacancies.