Growth and formation of hybrid structures on InP by alternated anodizations in aqueous media and liquid ammonia

Results about electrochemical anodic passivation of indium phosphide formed sequentially in two electrolytes with contrasted properties are reported for the first time. Using a galvanostatic method, oxidation of the InP surface has been formed initially at pH 9 with a current density of 0.2 mA cm⁻², while the anodization was achieved under illumination in liquid ammonia by cyclic voltammetry. Capacitance–voltage measurements in aqueous media coupled with cyclic voltammetry in liquid ammonia indicate the covering level of the two kinds of anodic layers, whereas XPS analysis gives access to chemical composition of hybrid structures. As a first result, the different measurements reveal the great stability of anodic oxide in liquid ammonia, at each step of oxide coverage. As a second result, the formation of a mixed layer with both oxide and “P–N” terminations has been evidenced by XPS. A new route of InP passivation was clearly established by this alternated anodization process.