NOVELTY - The method comprises heating and partially decomposing a nitrogen-containing precursor in a heated steel diffuser (140) to form nitrogen ions, partially decomposing a group III precursor to form indium ions and gallium ions, and forming indium gallium nitride (InGaN) from the nitrogen ions, the indium ions and the gallium ions within a chamber (102) at a growth rate of 5 Angstrom per second. The heating and partially decomposing step comprises flowing the nitrogen-containing precursor through the heated steel diffuser by exposing the nitrogen-containing precursor to a metal catalyst.    USE - The method is useful for forming InGaN (claimed) that is useful in a fabrication of a semiconductor device such as LEDs, laser diodes, photodiodes and solar cells.    ADVANTAGE - The method is capable of increasing a number of group V ions formed from group V precursors to enhance a growth rate of the InGaN in a simple and cost-effective manner.    DETAILED DESCRIPTION - The method comprises heating and partially decomposing a nitrogen-containing precursor in a heated steel diffuser (140) to form nitrogen ions, partially decomposing a group III precursor to form indium ions and gallium ions, and forming indium gallium nitride (InGaN) from the nitrogen ions, the indium ions and the gallium ions within a chamber (102) at a growth rate of 5 Angstrom per second. The heating and partially decomposing step comprises flowing the nitrogen-containing precursor through the heated steel diffuser by exposing the nitrogen-containing precursor to a metal catalyst and catalyzing decomposition of the nitrogen-containing precursor within the heated diffuser, heating the nitrogen-containing precursor in the heated diffuser to a temperature of 60-215 degrees C, and injecting the heated nitrogen-containing precursor into the chamber at the temperature. The method further comprises: flowing heated fluid through the diffuser to heat the diffuser; isolating the nitrogen-containing precursor from the heated fluid flowing through the diffuser; selecting the nitrogen-containing precursor to comprise ammonia; selecting the group III precursor to comprise a first gallium-containing precursor and a second indium-containing precursor; and applying microwave energy to the nitrogen-containing precursor without applying the microwave energy to the group III precursor. The step of flowing heated fluid through the diffuser comprises flowing oil through the diffuser and flowing fluorinated liquid through the diffuser. The step of forming the InGaN comprises growing the InGaN on a substrate (106) within the chamber, forming the InGaN on gallium nitride (GaN), forming the InGaN to have a defect density equal to or less than a defect density of the GaN, and forming a layer of InGaN having an average layer thickness of 0.5 micron. The microwave energy applying step comprises generating a plasma in an enclosure separate from the chamber using the microwave energy and passing the nitrogen-containing precursor through the enclosure.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic cross sectional view of a chemical vapor deposition system that is employed to perform a method for forming InGaN.    Chamber (102)    Substrate support structure (104)    Substrate (106)    Conduits (120)    Heated steel diffuser. (140)