Morphology evolution of mesoporous silicon powder formed by Pd-assisted chemical etching at temperatures of 25 – 75 °C

In this paper, we report the preparation of porous silicon powder by two-step Pd-assisted chemical etching with metallurgical grade polycrystalline silicon powder by varying the etching time from 30 to 90 minutes and solution temperature from 25 °C to 75 °C with and without thermal stabilization. A rapid temperature increase is observed with a maximum value of 95 – 100 °C in the case of etching without thermal stabilization. A high etching time of 90 minutes and a dissolution temperature above 50 °C have a negative effect on the formation of porous particles, which leads to the complete dissolution of silicon particles. The slow temperature growth for all initial temperatures in the case of the etching with thermal stabilization is observed. We established the positive effect of thermal stabilization in the process of etching on the thickness of the pores walls, reducing the uncontrollably growing rate of silicon etching, as a result, overetching of silicon.