Abstract
A new route of InP passivation was clearly ruled by an anodic electrochemical process in liquid ammonia as a relevant nonaqueous solvent. The coupling approach using both galvanostatic control and XPS analyses evidenced that this first protective film upon InP was definitely associated to one coating monolayer of general formula [ (H2N)P=N-]n. The electrochemical stability of the complete covering thin film was tested during hydrogen evolution in HCl aqueous solution. In spite of the high cathodic charge, unexpectedly no cathodic decomposition of the coated InP semiconductor was detected by XPS analyses. The electrical conductivity of this protective film and its electrochemical stability under negative overvoltage was then reported. In contrast to a bare InP, the electroless immersion of the protected InP in K2PtCl4 solution did not lead to the formation of metallic Pt cluster onto the substrate. On the contrary, the presence of amino groups in the film offered a unique opportunity for Pt (+II) grafting. A hybrid inorganic structure was proposed from the N/Pt atomic surface ratio, slightly higher than 2.0. The stability of the covered InP substrate as well as the ultra thin passivated film upon functionalization were also demonstrated from XPS analyses.