Abstract
The two-dimensional electron gas (2DEG) formed at the interface betweentwo band insulators LaAlO3 (LAO) and SrTiO3 (STO) is one of the mostfascinating systems in the field of oxide research. Tuning of theconductivity of this interface 2DEG and to create a spatially selectiveinsulating state is one of the key challenges in oxide electronics. Wefound that low Z ion irradiation can be utilized to manipulate theconductivity at the LAO/STO interface by carrier localization arising fromthe defects created by the ion beam exposure, and eventually producing aninsulating ground state. The results of electrical transport, Ramanspectroscopy and spectroscopic ellipsometry will be discussed. This processof ion induced defect creation results in structural changes in SrTiO3 asrevealed by the appearance of symmetry forbidden first-order TO2, andTO4 vibrationalmodes in the Raman spectra of the irradiated samples. In spectroscopicellipsometry measurements, the optical conductivity features of theirradiated interface were found to be broadened due to the localizationeffects along with a decrease of spectral weight from 4.2-5.4 eV. Theseresults indicate that the interface ground state (metallic/insulating) atthe LAO/STO can be controlled by engineering the SrTiO3 with ionirradiation. The consequences of the irradiation effects and possibleorigin of the reduction in conductivity will be discussed.
