Nucleation and faceting in selectively grown ZnS pyramidal dot array for short-wavelength light emitters

A ZnS dot array was selectively grown on (001) GaAs using metaloganic molec ular-beam epitaxy. The ZnS dot array has smooth facets and excellent unifor mity. To control the position of the active layer inside the dot structure which confines electrons and holes for small-sized light sources, the initi al growth process for the dot structure was studied in detail. It was found that delay time of growth initiation exists for small-area selective growt h. This delay was enhanced for smaller patterns The faceting of the grown s tructure, which determines the shape of the grown structure and controls th e output power from the small dot light source as an optical cavity, was al so discussed. The faceting was critically dependent on the orientation of t he mask opening. The dot structures selectively grown in the patterns the s ides of which are parallel to the [100] and [010] directions showed four sm ooth isotropic {034} related facets in the VI/II ratio from 0.5 to 3. When the mask opening was aligned parallel to the [110] and [(1) over bar 10] di rections, the dot structures showed {113}A facets in the [110] direction an d (110) and {113}B facets in the [(1) over bar 10] direction. These facets are anisotropic and change with the VI/II ratio.