Patent ID: 7560364

Claim:
A method for reducing dislocation density of a nitride semiconductor structure comprising an epitaxial layer, the method comprising: providing a substrate to a reaction chamber; forming an epitaxial nitride layer on the substrate, wherein the epitaxial nitride layer comprises lattice mismatch dislocations with the substrate, wherein forming the epitaxial nitride layer on the substrate comprises: introducing at least one nitrogen containing precursor into the reaction chamber; introducing a Group-III organo-metallic precursor and at least one etch compound into the reaction chamber, wherein the etch compound comprises a halogen compound and the at least one nitrogen-containing precursor reacts with the Group-III organo-metallic precursor to form a reaction mixture; and forming the epitaxial nitride layer on the substrate from the reaction mixture comprising the Group-III organo-metallic precursor and the at least one nitrogen-containing precursor under conditions sufficient to allow preferential etching of the lattice mismatch dislocations of the epitaxial nitride layer by the at least one etch compound during formation of the epitaxial nitride layer; preferentially etching the lattice mismatch dislocations of the epitaxial nitride layer during formation of the epitaxial nitride layer such that etch pits are formed at the locations of the lattice mismatch dislocations while epitaxial nitride layer is simultaneously grown within the etch pits to thereby prohibit threading of the lattice mismatch dislocations through the epitaxial nitride layer; stopping etching of the epitaxial nitride layer once the lattice mismatch dislocations are preferentially etched with etch pits; and forming a subsequent epitaxial nitride layer over the etched epitaxial nitride layer.