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

Processes for incorporating randomly oriented crystalline precipitates in a n amorphous host can be traced back to the 17th century when Cassius produc ed "gold ruby'' glass. In this glass, octahedral colloidal precipitates of gold scatter light by the Mie process to produce a deep red color. In contr ast to gold ruby glass, we describe a type of material in which the crystal line precipitates are crystallographically aligned in a coherent manner-eve n though they are dispersed in an amorphous matrix. Ion implantation and th ermal processing are first used to form zinc sulfide nanocrystals that are coherently oriented with respect to a crystalline Si host. The Si is then a morphized by ion irradiation leaving the highly radiation-resistant ZnS pre cipitates in an aligned crystalline state. The process is anticipated to fi nd applications in the creation of surfaces with unique optoelectronic prop erties. (C) 1999 American Institute of Physics. [S0003-6951(99)02905-8].