Cyclotron resonance and magnetotransport measurements in AlxGa1-xN/GaN heterostructures for x=0.15-0.30

Cyclotron resonance (CR) and magnetotransport experiments have been performed on modulation Si-doped AlxGa1-xN/GaN heterostructures with aluminum fraction x varying from 0.15 to 0.30. A clear CR absorption and Shubnikov-de Haas oscillations have been observed. The CR line shapes are analyzed by calculating the high frequency conductivity of a two-dimensional electron gas. The obtained electron effective mass m* and scattering time tau are found to depend on the aluminum fraction x. For x=0.30 the measured CR frequency shifts significantly upward, which demonstrates the formation of potential fluctuations in AlxGa1-xN/GaN heterostructures with large aluminum fraction x. (C) 2002 American Institute of Physics.