Electroreflectance and photoreflectance studies of AlGaN/GaN heterostructure with a QW placed inside AlGaN layer

摘要

Photoreflectance and electroreflectance spectroscopies are used for characterization of a AlGaN/GaN heterostructure with a QW. Analysis of Franz-Keldysh oscillations in AlGaN and GaN layers allow calculation of the electric-field dependence on bias in these layers. It was possible to obtain the concentration of charge localized in the QW and the polarization charge located at the AlGaN/GaN interface. The piezoelectric polarization was calculated using the lattice constants obtained from X-ray diffraction. Combining this with the electroreflectance results allowed the difference of spontaneous polarization between AlGaN and GaN layers to be obtained.