Deep levels and electron transport in AlGaN/GaN heterostructures

Based on the measurements of current-voltage and capacitance-voltage characteristics and deep-level transient spectroscopy, comparison of the concentration of deep-level centers and conductivity of the channel of the AlGaN/GaN heterostructures grown by molecular beam epitaxy with the use of ammonia as the nitrogen source is carried out. Two types of defects with deep levels are revealed. One type is presumably associated with point defects localized near dislocations, and the other type is associated with the dislocations themselves. An increase in the concentration of the centers with deep levels correlates with an increase in the channel resistivity. The density of the deep-level centers can attain values of $\sim$10$^{13}$ cm$^{-2}$ and lead to compensation of the electron channel at the heterointerface.