Method and apparatus for fabricating crack-free group iii nitride semiconductor materials

Abstract

Method for producing a III-N (AlN, GaN, Al x Ga (1-x) N) crystal by Vapor Phase Epitaxy (VPE), the method comprising: providing a reactor having: a growth zone for growing a III-N crystal; a substrate holder located in the growth zone that supports at least one substrate on which to grow the III-N crystal; a gas supply system that delivers growth material for growing the III-N crystal to the growth zone from an outlet of the gas supply system; and a heating element that controls temperature in the reactor; determining three growth sub-zones in the growth zone for which a crystal grown in the growth sub-zones has respectively a concave, flat or convex curvature; growing the III-N crystal on a substrate in a growth region for which the crystal has a by desired curvature.

1 . A group III-N (AlN, GaN, Al x Ga (1-x) N) crystal having:
 thickness at least 100 μm;   diameter equal to at least 2 inches; and   stress that is less than 0.1 gigapascal (GPa).   
     
     
         2 . A crystal according to  claim 1  wherein the crystal is crack-free. 
     
     
         3 . A crystal according to  claim 1  wherein the desired curvature is flat. 
     
     
         4 . A crystal according to  claim 1  having a bow below 50 microns. 
     
     
         5 . A crystal according to  claim 1  and having a diameter greater than or equal to about 4 inches. 
     
     
         6 . A crystal according to  claim 1  and having a diameter greater than or equal to about 6 inches. 
     
     
         7 . A crystal according to  claim 1  having thickness equal to or greater than about 1 mm. 
     
     
         8 . A crystal according to  claim 1  having thickness equal to or greater than about 10 mm. 
     
     
         9 . A crystal according to  claim 1  having thickness equal to or greater than about 50 mm. 
     
     
         10 . A crystal according to  claim 1  that appears crack-free under transmission and reflection optical microscopy at magnifications up to ×1000. (12/90) 
     
     
         11 . An AlN crystal according to  claim 1  having a thermal conductivity greater than 3.2 W/K-cm. 
     
     
         12 . An AlN crystal according to  claim 1  having an optical absorption less than 5% at wavelengths between 200 nm and 6 μm. 
     
     
         13 . An AlN crystal according to  claim 1  having an the x-ray rocking curve measured in ω-scanning geometry characterized by a full width half maximum (FWHM) that is less than 300 arc seconds.