Transformation of in grains to InN nanoshells with In₂O₃ as an intermediate state under a N₂-NH₃ ambient

InN nanoshells were fabricated by using nitridation of In grains sputtered on sapphire substrates. The X-ray diffraction intensities of the sputtered In grains measured before and after nitridation show that In grains were seemingly transformed directly to InN, but further microstructural analysis revealed that the transformation of In to InN involved In₂O₃ as an intermediate phase. Our result illustrates that the oxidation of the In grains at low temperatures was more favored than the nitridation process and that the fabrication of InN from the pure In grains under an atmospheric thermal process might inevitably follow this two-step pathway.