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-(GaSb)_1-x(Ge₂)ₓ(x=0 and 0.27) were investigated at high pressure. Discontinuous crystallization of a-(GaSb)0.73(Ge₂)0.27 occurs at 4.7 GPa. In a-(GaSb) the continuous volume anomaly occurs at 3-7 GPa, whereas the semiconductor-to-metal transition occurs at 3-4 GPa. Metallization of a-(GaSb) 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 and 0.27, respectively) than that of crystalline (GaSb) (55 GPa) and exhibit strong softening long before the transitions.