Amorphous semiconductor/electrolyte junction. Interference effects during the growth of anodic Nb2O5 films under absorbed light

Abstract

Photoeffects, revealed during the growth of anodic oxide films on niobium under illumination, confirm the existence of interference effects at wavelengths well below the absorption edge of the films. Such effects were observed for films grown in different ways at various growth rates and vanish only at very short wavelengths. The experimental results suggest an efficiency of carrier generation close to one due to the very high electric fields existing inside the growing film. The fitting of the experimental curves (photocurrent or photovoltage vs. thickness) at long wavelengths allowed the estimation of the mobility times lifetime products for both photocarriers. Experiments performed at very short wavelength indicate that the hole is the slow photocarrier in anodic Nb₂O₅ films. The influence of illumination and of the ionic fluxes on the electron lifetime is reported. Useful information on the kinetics of film growth can be obtained from photoelectrochemical measurements.