Fabrication influence on the surface morphology and structure of vapour etched porous silicon

Anotacija

The structure and properties of porous silicon produced applying vapour-phase chemical etching of Si in HF : HNO3 acid mixture are analysed. Experimental layers of different porosity with pores of different size and shape corresponding to different active surface areas, were formed by varying the etching parameters. The fabricated structures were investigated using the X-ray diffractometry (XRD), Raman spectroscopy (RS), infrared spectroscopy (FTIR) and photoluminescence spectrometry (PL) methods. SEM imaging was used for the visualization of the produced structures. The refractive index of the experimental layers was evaluated by optical ellipsometry measurements and used for layer porosity estimation. The crystallite size in the fabricated porous structures was estimated taking into account the presence of porous (p-Si), crystalline (c-Si) and amorphous (a-Si) structures in the experimental layers. The size of crystallites in the porous Si layers was found to vary from 3.1 nm to 4.3 nm, and layer porosity varied from 61.4 to 86.7% in different samples. Fabrication of mesoporous silicon structures containing nanosized crystallytes, achieved by controlling vapour-phase chemical etching parameters, is discussed on the basis of the obtained results. Keywords: vapour-phase etching, porous Si, nanocrystalline, mesoporous structure