Pressure controlled droplet spraying (PCDS) method for forming particles of compound materials from melts
A method and apparatus of forming compositionally homogeneous particles is provided. The method includes forming a homogenous melt from a plurality of constituent materials under a first pressure sufficient to prevent substantial vaporization of the constituent materials. Droplets are generated from the homogenous melt. The droplets are cooled under a second pressure sufficient to prevent substantial vaporization of the constituent materials at least until the homogeneous particles formed therefrom have stabilized.
1. A method of forming compositionally homogeneous layers, comprising:
forming a homogeneous melt from a plurality of constituent materials that have different vaporization rates, the homogeneous melt being formed under a first pressure sufficient to prevent compositional changes in the homogeneous melt due to selective vaporization of the constituent materials, wherein the constituent materials are compound semiconductor materials;
generating droplets from the homogeneous melt; and
applying the droplets to a substrate under a second pressure sufficient to prevent substantial compositional changes in the droplets due to selective vaporization of the constituent materials so that a homogeneous layer is formed upon cooling.
2. The method of claim 1 further comprising applying the droplets to the substrate under the second pressure so that a plurality of homogeneous layers is formed.
3. The method of claim 2 wherein the plurality of homogeneous layers forms a preform structure.
4. The method of claim 1 wherein the homogeneous melt is formed above its liquidus temperature.
5. The method of claim 1 wherein the first pressure arises from an inert gas.
6. The method of claim 1 wherein the second pressure arises from an inert gas.
7. The method of claim 1 wherein the second pressure arises from a reactive gas.
8. The method of claim 1 wherein generating the droplets further comprises mixing the homogeneous melt with an inert gas stream while maintaining the homogeneous melt at a specified temperature at least until the droplets are formed.
9. The method of claim 1 wherein generating the droplets is performed using a spray nozzle.
10. The method of claim 1 wherein the homogeneous melt is formed from a solid body that is melted in a droplet generation vehicle that generates the droplets.
11. The method of claim 1 further comprising transferring the homogeneous melt from a melting vessel to a droplet generation vehicle using a gas pressure differential.
12. A method of forming compositionally homogeneous layers, comprising:
mixing in a melting vessel a plurality of constituent materials that have different vaporization rates, wherein the constituent materials are compound semiconductor materials;
forming a homogeneous melt from the plurality of constituent materials, the homogeneous melt being formed under a first pressure sufficient to prevent compositional changes in the homogeneous melt due to selective vaporization of the constituent materials;
generating droplets from the homogeneous melt; and
applying the droplets to a substrate under a second pressure sufficient to prevent substantial compositional changes in the droplets due to selective vaporization of the constituent materials so that a homogeneous layer is formed upon cooling.