White light emission from fluorescent SiC with porous surface

We report for the frst time a NUV light to white light conversion in a N-B co-doped 6H-SiC (fuorescent SiC) layer containing a hybrid structure. The surface of fuorescent SiC sample contains porous structures fabricated by anodic oxidation method. After passivation by 20nm thick Al2O3, the photoluminescence intensity from the porous layer was signifcant enhanced by a factor of more than 12.

Using a porous layer of moderate thickness (~10µm), high-quality white light emission was realized by combining the independent emissions of blue-green emission from the porous layer and yellow emission from the bulk fuorescent SiC layer. A high color rendering index of 81.1 has been achieved. Photoluminescence spectra in porous layers fabricated in both commercial n-type and lab grown N-B co-doped 6H-SiC show two emission peaks centered approximately at 460nm and 530nm.

Such bluegreen emission phenomenon can be attributed to neutral oxygen vacancies and interface C-related surface defects generated dring anodic oxidation process. Porous fuorescent SiC can ofer a great fexibility in color rendering by changing the thickness of porous layer and bulk fuorescent layer.

Such a novel approach opens a new perspective for the development of high performance and rare-earth element free white light emitting materials.