Droplet epitaxy is an important method to produce epitaxial semiconductor quantum dots (QDs). Droplet epitaxy of III-V QDs comprises group III elemental droplet deposition and the droplet crystallization through the introduction of group V elements. Here, we report that, in the droplet epitaxy of InAs/GaAs(001) QDs using metal-organic chemical vapor deposition, significant elemental diffusion from the substrate to In droplets occurs, resulting in the formation of In(Ga)As crystals, before As flux is provided. The supply of As flux suppresses the further elemental diffusion from the substrate and promotes surface migration, leading to large island formation with a low island density.

Glass ceramic materials were fabricated based on BaO-ZnO-B 2 O 3 (BZB) glass with Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 ceramics. It was investigated that the dielectric properties and the sintering behaviour of glass ceramics. Doped by BZB glass, the sintering temperature of Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 ceramics was significantly lowered to 900uC in comparison to 1300uC for samples without glass. The low softening point BZB glass provided good wetting between BZB and Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 , and the reaction between glass and ceramics was increased. The dielectric constant of BZB-Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 system was increased with increasing firing time. The composite sintered at 900uC for 2 h exhibited excellent dielectric properties were achieved, with dielectric constant of 75, the dielectric loss of 5610 25 and the temperature coefficient of ¡30 ppm uC 21 .