Etch tapered angle on the influence of GaN membrane grating reflectance spectra

The technique of backside thinning is used to obtain thinner freestanding GaN membrane. This technique is helpful for producing stronger reflectance peaks and to reduce the reflectance spectra quantity and reflectance interference in the visible light range. Ion beam etching (IBE) was used to fabricate a GaN membrane grating, and the size of the tapered angle of which has an important affect on the reflectance spectra modes. Therefore, we presented a GaN membrane grating model with tapered angle which is built based on a GaN-on-silicon wafer structure. The influence of the varied tapered angle on the reflectance spectra of grating was investigated. Meanwhile, affects of different parameters like the grating thickness, membrane thickness, grating period, filling factor, incident beam based on a certain tapered angle were also analyzed on reflectance spectra of the GaN grating. Rigorous coupled wave analysis (RCWA) was used as theoretical principle for numerical simulations on the GaN grating model in this study. The results of this report are very useful for fabricating GaN reflectance photonic devices, such as refractive index sensor, couplers and so on.