Quasi-zero-voltage controlled etching of macropores in n-type silicon

Here, we report an experimental study about the controlled etching of macropores in n-type silicon electrodes at quasi-zero anodic voltage using hydrofluoric acid-based photo-electrochemical etching (P-ECE). This breaks a new ground on the controlled electrochemical dissolution of n-type silicon, for which the use of anodic voltage above the electropolishing peaks (Vps, Jps) has been considered to be a golden rule for the etching control, so far. Remarkably, our experimental results clearly show that it is possible to control the etching of macropores at anodic voltages well below (close to zero Volt) the electropolishing peak and that the use of low anodic voltages is beneficial for the fabrication of regular macropores with large diameter (i.e. 10 ?m) and spatial pitch (i.e. 20 ?m).