Physical studies ofAuxSi1−xamorphous alloys

Amorphous films of the system ${\mathrm{Au}}_x{\mathrm{Si}}_{1-x}$ have been prepared by vapor deposition over a wide compositional range ($0<x<\mathrm{}0.8\mathrm{}$). Their physical properties, their stability in the amorphous state, and the crystallization mechanisms have been investigated by electronic microscopy and diffraction, electrical-resistivity and mass-density measurements. The results are compared with those obtained in the liquid alloys, liquid quenched glasses, and getter sputtered films of the same system. Some similarities in short-range orders of all these materials are suggested especially near the eutectic composition. The present study would also suggest that Au-rich alloys near the ${\mathrm{Au}}_3$Si composition ($a-\mu$ phase) have a close-packed metallic structure, while the alloys of the Si-rich end exhibit a more open continuous-random-network-like structure with Au atoms in interstitial sites ($a-\mathrm{Si}$ phase), amorphous alloys in the intermediate-composition range being an intricated mixture of both $a-\mu$ and $a-\mathrm{Si}$ phases. Before reaching the equilibrium dissociation into crystalline Au and Si, crystallization occurs via a diffusionless transformation into a crystalline $c-\mu$ phase (alone or with silicon) whose short-range order is compared with that of the $a-\mu$ phase. Electrical properties and stability are discussed within the framework of this model.