Near-interface charged dislocations in AlGaN/GaN bilayer heterostructures

Abstract

Understanding the behavior of semiconductor dislocation defects in AlGaN/GaN heterostructures is necessary in order to produce powerful and efficient transistors. This letter presents a straightforward technique to characterize dislocation defects with charges along their loops in a bilayer system. This is important regarding the behavior of near-interface dislocations in order to obtain an insight of the mechanical and physical responses. We characterize piezoelectric polarization and emphasize on the importance of dislocation-core electric charge. The results elaborate the variations of the dislocation force by the accumulation of charge and provide an explanation for the dominant dislocation types in nitride semiconductors.

Correlation of structural and optical properties of AlGaN films grown on SiN-treated sapphire by MOVPE

“…11. The orientation of threading dislocation lines along direction has also been experimentally observed for grown epitaxial GaN layers [34]. The best linear fit of the two data sets of Fig.…”

“…The internal stress due to the lattice mismatch is the main cause of the formation of misfit dislocations. Threading dislocations, however, are generated as a result of the coalescence of adjacent grains during epitaxial growth at high temperatures with a density ranging between 10 8 and 10 11 cm −2 [34]. Furthermore, it has been demonstrated that the most dislocations in AlGaN/GaN heterostructures are of threading straight type [34].…”

“…The change in the internal electric field in AlGaN is ascribed to the change of two main components: the polarization-induced electric field and the dislocations-induced electric field [34,51]. However, no clear experimental evidence of the magnetite of each component has been reported so far.…”

Effects of the diameter of thermally generated nanopits on carrier dynamics in AlGaN/GaN heterostructures

“…reported that the built-in electric field in AlN/GaN/AlN heterostructures enhances the electron–phonon interaction via the deformation potential and the piezoelectric potential. In our samples, when the nanopits diameter is increased, the built-in electric field is expected to rise due to increasing defect density 4 , 37 …”

“…These nanopits are commonly observed in III-nitride heterostructures and associated with misfit and threading dislocation terminus 35 , 36 . While threading dislocations are generated through the coalescence of adjacent grains during growth, misfit dislocations are formed due to the internal stress caused by the lattice mismatch between the (Al)GaN layer and the substrate 37 . Misfit and threading dislocations can be entangled with each other during growth to form closed or open dislocation loops that prolong toward the top surface of the epitaxial layer.…”