The role of the flat-band potential in porous silicon formation

Abstract

It is generally accepted that porous silicon formation requires the semiconductor/electrolyte interface to be under depletion conductions, with electropolishing occurring once the bias is sufficiently positive to cause accumulation conditions to occur. It is thus logical to conclude that porous silicon formation ceases at the flatband potential. In our previous publication we postulated that the flatband potential is marked on a typical IV curve by the transition from an exponential to a linear relationship between the applied potential and resulting current density. Here we confirm this hypothesis by comparing this transition potential with calculated theoretical flatband potentials and finding excellent agreement between these two parameters over a wide range of silicon wafer conductivities and HF concentrations. © 2012 The Electrochemical Society.