Effects of "P-N" Terminations on the Initial Stages of Pore Growth onto n-InP in HCl Aqueous Solution

Abstract

In this paper we report, for the first time, a galvanostatic control in 1M HCl aqueous solution onto a InP surface that had been previously entirely nitrogenated. The surface nitrogenation required an anodic electrochemical treatment in acidic liquid ammonia (NH3 liq.). An homogeneous covering film with " P-N " terminations was obtained onto the InP surface properly deoxidized. This thin film is notable for its lack of air ageing and also for its chemical stability in HCl. A galvanostatic control at different current density (10 mA.cm-2, 100mA.cm-2 and 300 mA.cm-2) in 1M HCl was used to identify the effect of this " P-N " terminations on the porosification process. In comparison to a bare surface, a contrasted evolution of the interfacial potential was clearly observed for low current density. As expected, a crystal oriented pore morphology (CO) is obtained onto a bare InP surface whereas "oscillating" current line oriented pore morphology (CLO) is kept onto a surface entirely recovered by a " P-N " film. The presence of the nitrogenated film can therefore be significant on the pore growth evolution in 1M HCl aqueous solution.