Epitaxial Layers Versus Bulk Single Crystals of GaN. Temperature Studies of Lattice Parameters and Energy Gap |
H. Teisseyre, P. Perlin, M. Leszczyński, T. Suski, L. Dmowski, I. Grzegory, S. Porowski, J. Jun High Pressure Research Center "Unipress", Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warszawa, Poland and T.D. Moustakas Boston University, Molecular Beam Epitaxy Laboratory, Department of Electrical, Computer and System Engineering, Boston MA 02215, USA |
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Gallium nitride epitaxial layer grown by molecular beam epitaxy and bulk crystal grown at high pressure were examined by using X-ray diffraction methods, and by optical absorption at a wide temperature range. The free electron concentration was 6 × 1017 cm-3 for the layer and about 5 × 1019 cm-3 for the bulk crystal. The experiments revealed a different position of the absorption edge and its temperature dependence for these two kinds of samples. The structural examinations proved a significantly higher crystallographic quality of the bulk sample. However, the lattice constants of the samples were nearly the same. This indicated that a rather different electron concentration was responsible for the different optical properties via Burstein-Moss effect. |
DOI: 10.12693/APhysPolA.87.403 PACS numbers: 65.70.+y, 78.50.Ge, 78.66.Fd |