Electron beam induced epitaxial crystallization in a conducting and insulating a-LaAlO₃/SrTiO₃ system

Interfacial conductivity at the interface between two insulating oxides, that is 2DEG, shows a number of intriguing properties and applications, such as on/off switching with external electric fields, use in nanoscale electronic devices and tunable conductivity. Here, we report the effect of the interfacial conductivity on the kinetic behavior of electron-beam-induced epitaxial crystallization of an oxide amorphous thin film on an SrTiO₃ substrate. Epitaxial growth from the interface can occur without direct e-beam irradiation at the interface due to accumulated charge around the beam position in the insulating materials. 2DEG, which acts as a current path delays the crystallization kinetics, thus delicate control of the crystallized pattern shape and size is available. As a result, successful pattern writing with a width of about 5 nm was performed. The present work provides useful guidelines for coherent atomic scale e-beam patterning considering the critical distance of the electron beam from the interface for the epitaxial growth, e-beam dose rate effect on the growth rate and the heterostructure interfacial conductivity.