Oliver Riemenschneider

Smoothening the Pores Walls in Macroporous n-Si

Our work reports on the etching of very smooth pores in n-Si with backside illumination. From the point of view of the so- called current burst model we explain the origin of the roughness on macropore walls. By trying different types of electrolytes at very low or moderate pH, electrolytes with very small dissolution rates of SiO2, or etching at very low temperatures, we show that the roughness of the walls can be controlled. Finally we propose to use a viscous electrolyte which lead to a roughness of only 9 nm on a 800 x 800 nm2 area which is a factor 5 smaller than the roughness observed for aqueous electrolytes.