Verification of threading dislocations density estimation methods suitable for efficient structural characterization of AlxGa1−xN/GaN heterostructures grown by MOVPE

Abstract

Selection of a suitable chemical etching method for threading dislocations density estimation is crucial for the structural characterization of epilayers grown by MOVPE and thus further for device fabrication. In this work, threading dislocations density in single layer and AlxGa1−xN/GaN periodical heterostructures has been investigated by means of chemical etching and XRD analysis. For chemical etching, two types of agents have been used: phosphoric acid (220°C/7.5min) and a molten mixture of KOH-NaOH (440°C/2.5min). Estimation of dislocation density has been carried out on the basis of SEM images. It was shown that defect-selective etching in molten alkaline solution is more effective than etching in phosphoric acid and provides more accurate data that are in agreement with data obtained from XRD characterization.