Effects of Illumination and Ferroelectric Field on Nanoscale Al:ZnO Films: Implications for Nonvolatile Multistage Storage and Photosensor Devices

In this work, the nanoscale Al:ZnO (AZO) films with various densities of oxygen vacancies were grown on 0.7PbMg_1/3Nb_2/3O₃–0.3PbTiO₃ single crystal substrates. The Kelvin probe force microscopy and Hall effect were used to investigate the surface potential and carrier density modulated by the ferroelectric field and illumination effects. Tunable carrier densities and resistivity were obtained in the AZO films by changing the density of the oxygen vacancies. The carrier density can be largely modulated by the ferroelectric field effect in the AZO films with lower carrier density. The surface potential gradually increases under illumination, which can be attributed to the relaxation of the photoconductivity. As a result, the various semiconducting properties of the AZO films were achieved by the combination of ferroelectric field and illumination effect. Our results have potential applications for nonvolatile multistage storage and photosensor devices.