Dislocation-Induced Local and Global Photoconductivity Enhancement and Mechanisms in Iron-Doped SrTiO3

Abstract

Dislocations have a tremendous potential to alter band structure and transport properties. However, their impact on the optoelectronic properties of metal oxides is not thoroughly studied. This is mostly due to the early work on classical semiconductors, where dislocations are found to have detrimental effects. In this study, a simple method is developed to introduce a high density of dislocations over a large macroscopic volume of Fe-doped SrTiO₃ single crystals. As a result, the photoconductivity revealed by static and dynamic measurements increases by at least one order of magnitude. A detailed analysis based on photo-Hall, spectral photoresponsivity, time-resolved photocurrent, and conductive AFM, focusing on the quantum paraelectric state of SrTiO₃, is presented to shed light on the possible mechanisms behind higher generated photocurrent. These findings indicate that the increased photoconductivity results from a higher charge carrier generation rate due to new energy states induced by dislocations, possibly accompanied by an enhancement of electron effective mass.