Size-Controlled Spalling of LaAlO/SrTiO Micromembranes.

The ability to form freestanding oxide membranes of nanoscale thickness is of great interest for enabling material functionality and for integrating oxides in flexible electronic and photonic technologies. Recently, a route has been demonstrated for forming conducting heterostructure membranes of LaAlO and SrTiO, the canonical system for oxide electronics. In this route, the epitaxial growth of LaAlO on SrTiO resulted in a strained state that relaxed by producing freestanding membranes with random sizes and locations. Here, we extend the method to enable self-formed LaAlO/SrTiO micromembranes with control over membrane position, their lateral sizes from 2 to 20 μm, and with controlled transfer to other substrates of choice. This method opens up the possibility to study and use the two-dimensional electron gas in LaAlO/SrTiO membranes for advanced device concepts.