Regensburg 1998 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 2: Poster I

HL 2.21: Poster

Montag, 23. März 1998, 10:30–19:00, A

Cathodoluminescence of cubic GaN epilayers — •C. Wang, D.J. As, B. Sch"ottker, D. Schikora, and K. Lischka — Universit"at GH Paderborn, FB6 Physik, 33095 Paderborn

Cubic GaN (c-GaN) epilayers grown on (100) GaAs substrates by rf-assisted MBE are investigated using cathodoluminescence (CL). At room temperature the full width at half maximum of the band edge transition is 56  meV with the peak centered at 3.2  eV. To our best knowledge, this is the narrowest room temperature linewidth reported for the c-GaN epilayers. The low temperature CL-spectra are dominated by an excitonic transition line with a binding energy of 26  meV. A broad emission band peaked at 2.4  eV is observed at low excitation intensity. While this luminescence band is extremely weak at high excitation level. The gap edge luminescence depends linearly on the electron beam excitation intensity, while the deep luminescence shows a saturation at high excitation level. Depth and spatially resolved CL illustrates that the density of non-radiative recombination centres is strongly increasing towards the GaN/GaAs interface and the crystal quality is improved with increasing the epilayer thickness.