EFFECT OF ANTIMONY ON THE SEMICONDUCTING PROPERTIES OF THE ANODIC PLUMBOUS OXIDE FILM FORMED IN SULFURIC-ACID-SOLUTION .1. STUDIES WITH ALTERNATING-CURRENT (AC) IMPEDANCE

The semiconducting properties of the anodic plumbous oxide films formed on lead and lead-antimony alloys in 4.5 M H2SO4 (20-degrees-C) at 0.9 V (versus Hg/Hg2SO4) for 2 h have been studied using the a.c. method. From the Mott-Schottky plots, the films are demonstrated to be n-type semiconductors. The flat-band potentials of the films on Pb, Pb-1at.%Sb, Pb-3at.%Sb and Pb-9at.%Sb are -0.95, -1.0, -0.69 and -0.70 V (versus Hg/Hg2SO4), respectively; while the corresponding donor densities are 0.82 x 10(16), 1.2 x 10(17), 5.5 x 10(17) and 6.3 x 10(17) cm-3. The shift of the flat-band potential to more positive values with increase in the antimony content is probably due to the occlusion of a Sb2O3 phase in the film. The effect of antimony on the donor density and the lattice-defect density of the n-type semiconductor oxide both conform to the Hauffe Rules.