Summary: Optical constants of cubic GaN in the energy range of 1.5­3.7 eV
U. Ko¨hler, D. J. As, B. Scho¨ttker, T. Frey, and K. Lischka
Universita¨t Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany
J. Scheiner, S. Shokhovets, and R. Goldhahna)
Institut fu¨r Physik, TU Ilmenau, PF 100565, 98684 Ilmenau, Germany
Received 17 September 1998; accepted for publication 24 September 1998
The refractive index and extinction coefficient of cubic GaN in the energy range of 1.5­3.7 eV were
determined with high accuracy using combined reflectivity and spectroscopic ellipsometry studies
of layers grown by molecular beam epitaxy on GaAs 001 . A comparison of the experimental
reflectivity data with theoretical calculations demonstrates that the data analysis has to be performed
by taking into account both surface roughness and a nonabrupt substrate­film interface. In the
transparent region the refractive index of cubic GaN was found to be slightly higher than that of the
hexagonal modification. © 1999 American Institute of Physics. S0021-8979 99 02501-3
I. INTRODUCTION
In current semiconductor research, materials offering a
large direct band gap face a still growing interest. This is
especially valid for GaN and its alloys that additionally pos-
sess considerable mechanical hardness and chemical inert-
ness. Recent achievements include long time cw emission of
wurtzite structure h-GaN based laser diodes.1

Source: As, Donat Josef - Department Physik, Universität Paderborn

Collections: Materials Science; Physics