Nonequilibrium phase transitions and amorphization in Si, Si/GaAs, Ge, and Ge/GaSb at the decompression of high-pressure phases

The evolution of nonequilibrium phase transitions during the decompression of high-pressure modifications of Si, Si/GaAs, Ge, and Ge/GaSb at different temperatures was studied. At temperatures below 120 K, the amorphization of Si and Ge high-pressure phases occurs upon the release of pressure. The positions of the transitions to metastable crystalline Si and Ge phases and of the amorphization of silicon and germanium on the P-T plane were found. The increase of the concentration of the ${\mathit{A}}^3$ ${\mathit{B}}^5$ components in Si-based and Ge-based solid solutions (GaAs in Si and GaSb in Ge) leads to the same change of the type of transitions as the decrease of the temperature does. This makes the preparation of bulk amorphous tetrahedral Si-based and Ge-based semiconductors possible, using the decompression of high-pressure phases, even at room temperature. The kinetics of the nonequilibrium transitions to crystalline phases and of the amorphization is briefly discussed.