Sensitivity to Curvature

A particularly important property of silicon electrodes is the sensitivity of the rate of electrochemical reactions to the radius of curvature of the surface, i.e., the sensitiv- 

The distribution of chemical reactions which do not involve charge carriers in the semiconductor is not affected by surface curvature. Thus, formation of pores does not occur in KOH solutions where the dissolution of silicon is of almost 100% chemical nature. Also, the effect of surface curvature is little when the surface is covered with an oxide film which masks the semiconductor properties of silicon, e.g., during electropolishing in HF. 

The sensitivity depends on the radius of curvature relative to the width of space charge layer. This effect can be measured by a normalized parameter X = Jr, defined as relative curvature. At X = 1, i.e., when the radius of curvature is in the order of the width of space change layer the electrochemical reactions will be significantly affected (see Fig. 8.64). Thus, for any electrochemical reactions that can cause the surface geometry to change, eito a dissolution or deposition, the surface distribution 

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