Porosity determination equation for porous silicon

Through the studying of the carriers moving of the porous silicon as well the definition of S_BET, the equation of the relationship between porosity, current density and etching speed can be deduced. It is shown that there is a universal relationship for porous silicon made from p-type silicon, it is possible to determine the change in porosity with respect to etching under a set of etching current density. This relationship is certificated by experimental data from several reports on these etching parameters.

在制备多孔硅材料时，多孔硅的多孔度和厚度与电解电流强度、电解时间以及氢氟酸的浓度有关。如果氢氟酸的浓度保持不变，通过改变电解时间和电解电流强度就可以得到所需多孔硅的多孔度及厚度。但现在一般都通过测量设备來重复测量多孔硅的多孔度及厚度，特别是多层多孔硅，很难严格控制其厚度。为此，通过对多孔 硅中载流子运动的研究，结合BET方程中的S_BET定义，推导出多孔硅的多孔度、电解速度和电解电流强度之间的关系表达式，通过该理论公式，就可以保证精确得到多孔硅的多孔度及厚度。该理论公式得到了实验的验证。