LAUSR

(Photo)electrochemical processes occurring under cathodic polarization at the p-GaInP2(100)/1 M HClaq solution interface were investigated in detail by high-resolution surface sensitive synchrotron-radiation photoemission spectroscopy. It was found that on application of the cathodic bias in the dark to the p-GaInP2(100)/1 M HClaq solution interface the electrochemical processes are started at a bias of about −1.0 V vs reversible hydrogen electrode (RHE), where cathodic current passing through the semiconductor/electrolyte interface starts to rise. Under higher cathodic bias applied in the dark, hydroxyl groups and metallic gallium are accumulated at the surface, which is accompanied by a decrease in work function of the semiconductor. Accumulation of hydroxyl groups can be related only to splitting of water molecules at the semiconductor/electrolyte interface, since the aqueous HCl solution contains no hydroxyl groups intrinsically. Accumulation of hydroxyl groups and metallic gallium is accelerated unde...