A photoelectrochemical study of anodic oxides on lead selenide surfaces inalkaline solutions

Lead selenide is a narrow gap semiconductor material. It finds applications in infrared emitting and detecting devices. Their performance is closely r elated to charge carrier recombination at the surface, which can be reduced by passivation, e.g. due to PbSeO3 formation by anodic oxidation in alkali ne solutions. In dependence on the pretreatment of the surface, two differe nt types of oxide formation were observed. To determine the electronic prop erties of the anodic oxide, the wavelength dependence of the photocurrent w as investigated. The energy of the band gap of both types of anodic oxide o n PbSe has been determined to be 2.4 eV for the direct and 1.8 eV for the i ndirect band gap. A weakening of the photocurrent generated in the bulk (Pb Se) due to scattering or absorption within the oxide confirms the potential dependence of the oxide thickness for a high field growth mechanism.