Nature of Semiconductor-to-Metal Transition and Volume Properties of Bulk Tetrahedral Amorphous GaSb and GaSb-Ge Semiconductors under High Pressure

Electrical properties and compressibility of bulk amorphous semiconductors $a-{\left(\mathrm{GaSb}\right)}_{1-x}{\left({\mathrm{Ge}}_2\right)}_x(x=0\mathrm{} \mathrm{and} 0.27)$ were investigated at high pressure. Discontinuous crystallization of $a-{\left(\mathrm{GaSb}\right)}_{0.73}{\left({\mathrm{Ge}}_2\right)}_{0.27}$ occurs at 4.7 GPa. In $a-\left(\mathrm{GaSb}\right)$ the continuous volume anomaly occurs at 3-7 GPa, whereas the semiconductor-to-metal transition occurs at 3-4 GPa. Metallization of $a-\left(\mathrm{GaSb}\right)$ occurs by the percolation mechanism involving interaction of nanoregions with higher coordination. Bulk moduli of amorphous compounds at normal pressure are less (35 and 40 GPa for $x=0\mathrm{} \mathrm{and} 0.27$, respectively) than that of crystalline (GaSb) (55 GPa) and exhibit strong softening long before the transitions.