Facile thermal explosion synthesis and optical properties of Al-doped flatted 3C-SiC microcrystals with 4H-SiC quantum interlayers

A facile thermal explosion synthesis (TES) method is developed to in situ synthesize batches of high-quality Al-doped flatted 3C-SiC microcrystals. Structural and optical analysis reveals that one dimensional (1D) disordered regions, which structurally resemble wide band-gap 4H-SiC nano-interlays, are acquired and sandwiched in the 3C-SiC microcrystal matrix via Al doping. High-resolution transmission electron microscopy (HRTEM) studies demonstrate that both atomic arrangements with growth predominantly in the 〈1 1 1〉 direction and planar structural defects coexist in the Al-doped flatted 3C-SiC microcrystals. A stacking sequence model is adopted to explain the formation mechanism of 4H-SiC nano-interlayers induced via Al doping. The photoluminescence (PL) spectra analysis shows that a new intensive, sharp ultraviolet (UV) emission (3.5 eV) was observed for the flatted 3C-SiC microcrystal, except for a blue emission (3.1 eV) derived from the surface defects. It is speculated that the quantum confined effect induced by quantum barrier structures is responsible for the new sharp UV emission. This comprises the first report of using a TES method for the synthesis of flatted Al-doped SiC microcrystals. The present method suggests a unique technique for synthesizing quantum barrier structures in SiC microcrystal matrix, which could be extended to other doping elements, and gives a new insight to understand the PL behavior of SiC materials.