Studies of Defect Structure in Epitaxial AlN/GaN Films Grown on (111) 3C-SiC

• Published in: Nanomaterials (Basel, Switzerland) Switzerland), 2021-05, Vol.11 (5), p.1299
• Main Authors: Serban, Andreea, Ene, Vladimir, Dinescu, Doru, Zai, Iulia, Djourelov, Nikolay, Vasile, Bogdan, Leca, Victor
• Format: Article
• Language: English
• Subjects: Aluminum nitride; Aluminum oxide; Comparative analysis; defect density; Defects; Diffusion; Diffusion layers; Diffusion length; Dislocation; Dislocation density; Epitaxial growth; epitaxial thin films; gallium nitride; Gallium nitrides; Heterostructures; High resolution; High resolution electron microscopy; Interfaces; Optics; positron diffusion length; Sensors; Silicon carbide; Silicon substrates; Spectroscopy; Spectrum analysis; Transmission electron microscopy; X-ray diffraction
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano11051299

Several aspects such as the growth relation between the layers of the GaN/AlN/SiC heterostructure, the consistency of the interfaces, and elemental diffusion are achieved by High Resolution Transmission Electron Microscopy (HR-TEM). In addition, the dislocation densities together with the defect correlation lengths are investigated via High-Resolution X-ray Diffraction (HR-XRD) and the characteristic positron diffusion length is achieved by Doppler Broadening Spectroscopy (DBS). Moreover, a comparative analysis with our previous work (i.e., GaN/AlN/Si and GaN/AlN/Al2O3) has been carried out. Within the epitaxial GaN layer defined by the relationship F4¯3m (111) 3C-SiC || P63mc (0002) AlN || P63mc (0002) GaN, the total dislocation density has been assessed as being 1.47 × 1010 cm−2. Compared with previously investigated heterostructures (on Si and Al2O3 substrates), the obtained dislocation correlation lengths (Le = 171 nm and Ls =288 nm) and the mean distance between two dislocations (rd = 82 nm) are higher. This reveals an improved crystal quality of the GaN with SiC as a growth template. In addition, the DBS measurements upheld the aforementioned results with a higher effective positron diffusion length LeffGaN2 = 75 ± 20 nm for the GaN layer.