Exploration of Two-Dimensional Conductance Along LaAlO₃/SrTiO₃ Interface for Pressure Sensing

Dominated by the pressure-origin of strain gradient, the sensitivity of pressure sensor is usually enhanced by reducing the bulk thickness. Considering the degraded robustness of the thin sensing block, it is anticipated to achieve the pressure sensing with high sensitivity and robustness. To address the trade-off between the sensitivity and stability, this investigation explores the two-dimensional (2D) conductance along the LaAlO₃/SrTiO₃ (LAO/STO) heterojunction as the pressure-sensing block. In details, by the pulsed laser deposition (PLD), LAO is synthesized on the (001) STO substrate and the oxygen vacancies are formed along the LAO/STO interface. These heterojunction vacancies exhibit 2D conductance in characterization about the magnetic-field orientation-dependent magnetoresistance. The deionization energy of the oxygen vacancy is estimated to be 0.03 eV, by which the Fermi level is lifted to enable the LAO/STO heterojunction with the metallic characteristic. Fabricated into a pressure sensor, the LAO/STO heterojunction exhibits the sensitivity of 2.9 × 10^-6 Pa^-1 which is robust during the repeatability tests more than 100 times. It is confirmed that the 2D conductance can be explored toward pressure detection with comparable sensitivity and durativity.