Morphological evolution of the porous silicon surface for different etching time and current density in hf-ethanol solution

Abstract

Porous silicon samples were obtained by anodization process of a n-type silicon wafer. The pores formations were investigated by varying the electrochemical parameters like as current density and etching time.The main objective of the present study is to investigate the influence of these parameters in order to increase the surface area of the porous layer. Scanning electron microscopy and optical profilometer were used for morphological characterization, such as pore size, surface area and morphological evolution of the porous layer. The pores shape showed a tendency to be circular and then break with the increase of etching time as well as current density, resulting in a complex morphological with large surface area. In this work we were obtained surface area increases up to 185%. This information will be useful for future applications destined for material requiring high surface area, such as biosensor, gas sensor and substrate for film.Keywords: Porous silicon; Morphological evolution; Surface area. RESUMOAs amostras de silício poroso foram obtidas por processo de anodização das lâminas de silício tipo-n. As formações de poros foram investigadas variando os parâmetros eletroquímicos, tais como, Morphological evolution of the porous silicon surface for different etching time and current density in hF-ethanol solution Fig. 2 shows the top view image of a typical PS sample prepared by photoelectrochemical oxidation of n-type silicon, etching at different anodization time from 5 to 30 min and current density of 75 mA/cm. In general, there is a continuous evolution in the shape and size of the pores. It was observed that the shape, and the size of macropores are strongly influenced by the anodization time. By comparing the different anodization times it is observed that the superficial structures are more homogeneous as a function of increasing etching time. In Fig. 2(a), for 5 minutes etching time, it is possible to observe the growth of big and small pores, but small in higher amounts. However, the morphologic aspect of both is very similar. RESULTS AND DISCUSSION