Influence of free electrons and point defects on the lattice parameters and thermal expansion of gallium nitride

Research paper by M. Leszczynski, H. Teisseyre, T. Suski, I. Grzegory, M. Bockowski, J. Jun, S. Porowski, J. Bak-Misiuk, J. Domagala

Indexed on: 01 Feb '97Published on: 01 Feb '97Published in: Il Nuovo Cimento D


The paper reports on the changes of lattice parameters by free electrons (via deformation potential of the conduction band minimum) and by point defects (via size effect) for gallium nitride. The measurements were performed on single crystals grown at about 15 kbar and 1800 K and on homoepitaxial layers using high-resolution X-ray diffraction methods at temperatures 40–770 K. It was found that a high free-electron concentration increase both, the lattice parameters and thermal expansion. It was observed that most of the single crystals of gallium nitride possess different lattice parameters on their two sides and this difference increases at high temperature. The experimental results of X-ray diffraction, electron microscopy and Hall measurements served for creating a model of generation of low-angle boundaries in the pressure-grown single crystals.