Growth and characterization of high quality AlN using combined structure of low temperature buffer and superlattices for applications in the deep ultraviolet

Abstract

This study reports on the growth and characterization of AlN/AlxGa1−xN superlattices (SLs) for reduction of threading dislocations to grow high quality AlN layer. Insertion of optimized SLs is shown to effectively reduce the dislocation density, there by resulting in a high crystal quality 2.5-µm-thick AlN layer. It was found that full width at half-maximum (FWHM) of X-ray rocking curves (XRCs) around both (0002) and diffraction were decreased to 230 and 420, respectively. The results of XRC FWHM and dislocation densities from etch pit density (EPD) by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs are in a good agreement. This high quality and low dislocation density AlN layer is of key importance for high efficiency deep-UV light emitting diodes and power devices.