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 τ 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.

We report microphotoluminescence (μ-PL) mappings of CdZnTe wafers on micrometer and millimeter scales. The acquired PL spectra have been fitted to a model based on band-to-band transition including the contribution of localized states in the energy gap. The fitting yields energy gap Eg, which is correlated to the Zn fraction x in Cd1−xZnxTe. The statistics of large numbers of fitted Eg reveal the inhomogeneity of the Zn composition while the map of Eg gives the distribution of Zn atoms. The comparison between the PL mappings before and after epi-ready chemomechanical processing show a great improvement in homogeneity due to the removal of surface defects and damage by the processing. Our results demonstrate the feasibility of PL mapping in determining the Zn composition homogeneity and distribution in a CdZnTe wafer.