Process For Manufacturing A Gallium Rich Gallium Nitride Film

Abstract

A process for the manufacture of a gallium rich gallium nitride film is described. The process comprises (a) preparing a reaction mixture containing a gallium species and a nitrogen species, the gallium species and the nitrogen species being selected such that, when they react with each other, gallium nitride is formed; and (b) growing the gallium rich gallium nitride film from the reaction mixture, by allowing the gallium species to react with the nitrogen species and to deposit gallium nitride on a substrate selected from the group consisting of silicon, glass, sapphire, quartz and crystalline materials having a lattice constant closely matched to gallium nitride, including zinc oxide, optionally with a zinc oxide buffer layer, at a temperature of from about 480° C. to about 900° C. and in the presence of a gaseous environment in which the partial pressure of oxygen is less than 10 −4 Torr, wherein the ratio of gallium atoms to nitrogen atoms in the gallium rich gallium nitride film is from 1.01 to 1.20. The invention also provides the option of annealing the gallium rich gallium nitride film at a temperature of from about 20° C. to about 650° C. and for a time sufficient to decrease the resistivity of the film so that it becomes electrically conductive, for instance to a resistivity below 100 ohm.cm.

1 . Apparatus for the manufacture of a gallium rich gallium nitride film, comprising:
 (a) means for preparing a reaction mixture containing a gallium species and a nitrogen species, the gallium species and the nitrogen species being selected such that, when they react with each other, gallium nitride is formed; and   (b) means for growing the gallium rich, gallium nitride film from said reaction mixture, by allowing the gallium species to react with the nitrogen species and to deposit gallium nitride on a substrate, at a temperature of from about 480° C. to about 900° C. and in the presence of a gaseous environment in which the partial pressure of oxygen is less than 10 −4  Torr, wherein the ratio of gallium atoms to nitrogen atoms in the gallium rich gallium nitride film is from 1.01 to 1.20.   
   
   
       2 . Apparatus for the manufacture of a gallium rich gallium nitride film, comprising:
 (a) means for preparing a reaction mixture containing a gallium species and a nitrogen species, the gallium species and the nitrogen species being selected such that, when they react with each other, gallium nitride is formed; and   (b) means for growing the gallium rich gallium nitride film from said reaction mixture, by allowing the gallium species to react with the nitrogen species and to deposit gallium nitride on a substrate, at a temperature of from about 480° C. to about 650° C. and in the presence of a gaseous environment in which the partial pressure of oxygen is less than 10 −4  Torr, wherein the ratio of gallium atoms to nitrogen atoms in the gallium rich gallium nitride film is from 1.001 to 1.20; and   (c) means for annealing the said film at a temperature of from about 20° C. to about 700° C. for a time sufficient to decrease the resistivity of the gallium rich gallium nitride film to below 1000 ohm.cm.   
   
   
       3 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising means for controlling the temperature in step (b) between 500° C. and 650° C. 
   
   
       4 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , wherein the means for controlling the temperature in step (b) is capable of controlling the temperature at about 570° C. 
   
   
       5 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising means for controlling the partial pressure of oxygen in step (b) at less than 10 Torr. 
   
   
       6 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising a laser to induce, in step (b), the deposition on the substrate of the gallium nitride formed by the reaction mixture. 
   
   
       7 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising a remote nitrogen plasma to assist with the deposition of gallium nitride from the reaction mixture. 
   
   
       8 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising means for reducing the resistivity of the film, during the annealing step (c), to less than 250 ohm.cm. 
   
   
       9 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed  claim 1  or  claim 2 , comprising means for controlling during the annealing temperature during the annealing step (c) between about 50° C. and about 500° C. 
   
   
       10 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising means for providing, in step (b), a total pressure of between 0.1 Torr and 15 Torr. 
   
   
       11 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising means for evacuating the growth chamber to an absolute pressure of between 1.0×10 −5  Torr and 1.0×10 −8  Torr, before the reaction mixture is introduced 
   
   
       12 . Apparatus for the manufacture of a gallium rich gallium nitride film as claimed in  claim 1  or  claim 2 , comprising means for purging the growth chamber with nitrogen and means for evacuating the growth chamber to an absolute pressure of between 1.0×10 −5  Torr and 1.0×10 −8  Torr, before the reaction mixture is introduced thereinto.