Method of in situ stoiciometric and geometrical photo induced modifications to compound thin films during epitaxial growth and applications thereof

Abstract

In situ geometrical and stoichiometric properties of deposited films are brought about by employing a scanned irradiation source directed to a spot which is scanned across the growth surface in a chemical va GOVERNMENT RIGHTS The Government has certain rights in this invention pursuant to Contract No. 86F173100 awarded by the Defense Advanced Research Projects Agency (DARPA).

What is claimed is: 
     
       1. A method of photo thermal enhanced single crystal epitaxial growth in the deposition of Group III-V compound films comprising the steps of: a) providing a substrate in an epitaxial growth chamber having a growth surface;   b) heating the substrate to a temperature within the range of about 500° C. to 610° C.;   c) introducing reactant gases into said chamber comprising at least one Group III constituent and at least one Group V constituent such that decomposition of the reactant gases occurs at a selected substrate temperature in said range enabling deposition of a Group III-V compound film at said substrate growth surface; and   d) introducing an irradiation source into said chamber directed to selected regions on the substrate growth surface, said source characterized by a wavelength of operation substantially absorptive at the substrate growth surface as opposed to the reactant gases, the growth rate of said compound film within said temperature range in selected regions of the substrate surface illuminated by said source enhanced compared to unilluminated regions thereof whereby said illuminated regions contain a larger layer thickness and/or stoichiometric content compared to said unilluminated regions.   
     
     
       2. The method of photo thermal enhance epitaxy of claim 1 wherein said method has a diffusion-limited rate of growth, and said growth rate enhancement is between 2 and said diffusion-limited rate of growth. 
     
     
       3. The method of photo thermal enhanced epitaxy of claim 1 including the step of selecting a temperature in said range wherein optimized enhanced growth rates are achieved in the presence of said irradiated source to selectively provide different growth rate enhancements of deposition of compound films at spatially illuminated regions during film deposition. 
     
     
       4. The method of photo thermal enhanced epitaxy of claim 1 including the step of selectively controlling the growth rate enhancement of said compound film during its growth by varying said substrate temperature. 
     
     
       5. The method of photo thermal enhanced epitaxy of claim 1 wherein said source is a focussed laser beam, scanning said laser beam across said growth surface while modulating the intensity thereof to selectively increase or decrease the thickness and/or stoichiometric content of selected regions of said compound film as said film is being deposited. 
     
     
       6. The method of photo thermal enhanced epitaxy of claim 5 wherein said monotonic increase or decrease is induced by the profile Gaussian shape of said source spot. 
     
     
       7. The method of photo thermal enhanced epitaxy of claim 1 including the step of modulating the intensity of said source. 
     
     
       8. The method of photo thermal enhanced epitaxy of claim 7 including the step of shaping said laser beam to have a predetermined profile of varying intensity. 
     
     
       9. The method of photo thermal enhanced epitaxy of claim 8 wherein said profile is pseudo Gaussian shaped. 
     
     
       10. The method of photo thermal enhanced epitaxy of claim 1 wherein said source is a focussed laser beam, scanning said laser beam across said growth surface while maintaining constant intensity thereof to selectively increase or decrease the thickness and/or stoichiometric content of selected regions of said compound film as said film is being deposited. 
     
     
       11. The method of photo thermal enhanced epitaxy of claim 1 wherein said source is directed through a patterned mask to form an irradiated pattern on said growth surface.