R. Höpler

TL;DR: In this paper, the authors studied the dependence of the absorption edge and the refractive index of wurtzite AlxGa1−xN films on temperature and composition using transmission and photothermal deflection spectroscopy.

TL;DR: In this article, the correlation lengths and dislocation densities of hexagonal GaN grown by metallorganic chemical vapour deposition on c-plane sapphire are determined by transmission electron microscopy and triple-axis X-ray diffractometry.

TL;DR: In this article, the exact Al mole fraction and the biaxial strain of the alloys can be calculated by an additional determination of a, using asymmetric reflections, and the results obtained by x-ray diffraction and elastic recoil detection provide evidence for the validity of Vegard's law in the AlGaN system.

TL;DR: In this paper, the authors studied the Raman spectra of AlxGa1−xN layers grown by molecular beam epitaxy on sapphire substrates and determined the energy of the optical modes and the broadening of Raman peaks as a function of aluminum content.

TL;DR: In this article, the authors used spin resonance to study the dependence of intrinsic paramagnetic defects on Al mole fraction and found that doping with Si and Mg is increasingly difficult with increasing Al content because of a continuous shift of the donor and acceptor levels deeper into the bandgap.