Magneto-optical studies of GaN and GaN/Al x Ga1− x N: Donor Zeeman spectroscopy and two dimensional electron gas cyclotron resonance

Magneto-optical experiments have been performed on free and bound electrons in GaN films and GaN/AlGaN heterojunctions. Cyclotron resonance of two dimensional electron gas in GaN/ AlxGa1−xN heterojunctions has yielded m* = 0.23 m0, x-dependent scattering times consistent with values from transport measurements, and an apparent unexplained level crossing at 70 cm−1. Infrared absorption of doped GaN films has shown that the binding energy of Si donors, 29.0 meV, is much smaller than that of residual donors, in agreement with transport measurements, thus suggesting donor spectroscopy as a useful technique for defect/impurity qualitative analysis. Zeeman effect of the donor spectra has been used to determine the GaN low frequency dielectric constant, ε0 = 10.4.