Thermal expansion of bulk and homoepitaxial GaN

The thermal behavior of Mg-doped and intentionally undoped bulk crystals an d homoepitaxial GaN was investigated in a wide temperature range from 12 to 600 K. With high-resolution x-ray diffraction, both lattice parameters a a nd c were determined and the thermal expansion coefficients were calculated . Within the experimental accuracy, mean values were extracted for the temp erature ranges 12-100, 100-250, and 250-600 K. These values are essential, especially, for the interpretation of measurements of other GaN properties performed at low temperatures. (C) 2000 American Institute of Physics. [S00 03-6951(00)00336-3].