Low temperature photoluminescence study of AlxGa1−xN/GaN/AlxGa1−xN heterostructure nanocolumns

AlxGa1−xN/GaN/AlxGa1−xN/GaN/SiO2/Si (x = 0.12) heterostructure nanocolumns were grown by plasma-assisted molecular-beam epitaxy (PA-MBE). High-resolution transmission electron microscopy (HR-TEM) images show GaN single quantum (SQ) disk with average thickness of 3 nm and diameter of 20 nm. Reflection high electron diffraction (RHEED) images show the good growing surfaces throughout the nanocolumn heterostructure growth. High-resolution field effect scanning electron microscopy (HR-FE-SEM) characterizations show the good c-oriented GaN (0001) fiber texture. The photoluminescence study of GaN inserted in Al0.12Ga0.88N alloys nanocolumns at low temperatures are presented. The PL spectra at 10 K show a strong excitonic emission peak at 3.477 eV attributed to the donor-bound exciton (D0XA) of GaN. A strong emission peak at 3.54 eV is detected inferring the quantum confinement of excitons in the GaN SQ disk. Using Al0.12Ga0.88N as a barrier for GaN quantum disk inserted in the nanocolumnar structure improves the morphological and optical properties by reducing the strain/stress, when compared with AlN/GaN nanowires. Relieving the strain/stress in quantum well heterostructures is a crucial parameter for highly effective and reliable electrical and optoelectronic devices applications.