ELASTIC SOFTNESS OF AMORPHOUS TETRAHEDRALLY BONDED GASB AND (GE-2)(0.27)(GASB)(0.73) SEMICONDUCTORS

We have measured the longitudinal and transverse acoustic wave velocit ies in bulk pressure-amorphized alpha-GaSb and alpha-(Ge-2)(0.27)(GaSb )(0.73) semiconductors and in their polycrystalline analogs. Although the densities of crystalline and amorphous states were practically equ al, a significant softening of the bulk (29-35 %) and shear (41-46 %) elastic moduli has been found for amorphous phases. The ultrasonic dat a for bulk moduli are in good agreement with the previous direct volum etric measurements. Results of the present study combined with critica l review of previous works allowed us to find specific features of ela stic behavior of amorphous tetrahedral semiconductors (including group IV elements and group III-V compounds), and compare them to other cla sses of disordered solids.