Fabrication of GaN(1-x)Asx, Zinc-Blende, or Wurtzite GaN Depending on GaAs Nitridation Temperature in a CVD System

The study of GaN morphology and structure modification due to the variation of the nitridation temperature are reported. GaN is obtained by nitridation of GaAs (111) using the flow of a mixture of hydrogen and ammonia into a horizontal CVD system. The experiments are carried out at atmospheric pressures of 800, 900, and 1000 degrees C for 1h. XRD results together with the pole figure indicate that GaN(1-x)Asx is obtained at 800 degrees C, that zinc-blende GaN structure is obtained at 900 degrees C, and that wurtzite GaN structure is obtained at 900 degrees C. The photoluminescence emission peak (obtained at room temperature) shifts to 420, 384, and 372nm with the nitridation temperature change, in agreement with the XRD and pole figure results. SEM images show the morphology change, where GaN(1-x)Asx and GaN layers are obtained at 800 and 900 degrees C, respectively, while GaN columns are obtained at 1000 degrees C. The morphology and structure change due the nitridation temperature variation are also discussed based on the results.