POTENTIOSTATIC OXIDE FORMATION ON LEAD SELENIDE SINGLE-CRYSTALS IN ALKALINE-SOLUTIONS

Lead selenide is a narrow-gap semiconductor material. It finds applica tions in infrared emitting and detecting devices, with a performance c losely related to surface properties. Charge-carrier recombination at the surface can be reduced by passivation, for instance by formation o f a native oxide by anodic oxidation. in this work, the anodic behavio r of single-crystal lead selenide in aqueous solutions at pH 10 is stu died under potentiostatic conditions. Surface analysis using a scannin g electron microscope and energy dispersive X-ray spectroscopy was pet -formed. A ternary oxide was characterized as the oxidation product. T wo different growth mechanisms were found: an ''island growth'' (two-d imensional nucleus growth) and the growth of a homogeneous film follow ing the high-field model. The process of oxidation depends significant ly on the pretreatment of the lead selenide surface. The electronic pr operties of the oxidation laver were investigated with photocurrent me asurements, resulting in a bandgap of the anodic oxide of 1.6 eV. From I-V curves a specific conductivity was determined in the order of 10( -9) Omega(-1) cm(-1) for the oxide film.