PREPARATION OF HIERARCHICAL NETWORKS OF OUT-OF-PLANE/IN-PLANE PORES BY ELECTROCHEMICAL ETCHING OF SILICON THROUGH CONTROLLED INHIBITION OF BREAKDOWN EFFECTS

Silicon electrochemical etching is a well-known technique used for the preparation of both random and ordered porous silicon with tunable pore morphology and size for a wide range of applications [1,2]. However, the preparation of hierarchical networks of pores that synergistically integrate out-of-plane and in-plane pores at different length-scales with potential applications in different fields, e.g. energy storage [3], has not been achieved yet by silicon electrochemical etching. In this work, for the first time, hierarchical network of pores are prepared by back-side illumination electrochemical etching (ECE) of n-type silicon in HF-based electrolytes through controlled inhibition of electric breakdown (BD) at high anodic voltages.