Formation of oriented particles in an amorphous host: ZnS nanocrystals in silicon

Processes for incorporating randomly oriented crystalline precipitates in an amorphous host can be traced back to the 17th century when Cassius produced 'gold ruby' glass. In this glass, octahedral colloidal precipitates of gold scatter light by the Mie process to produce a deep red color. In contrast to gold ruby glass, we describe a type of material in which the crystalline precipitates are crystallographically aligned in a coherent manner even though they are dispersed in an amorphous matrix. Ion implantation and thermal processing are first used to form zinc sulfide nanocrystals that are coherently oriented with respect to a crystalline Si host. The Si is then amorphized by ion irradiation leaving the highly radiation-resistant ZnS precipitates in an aligned crystalline state. The process is anticipated to find applications in the creation of surfaces with unique optoelectronic properties. copyright 1999 American Institute of Physics