Influence of Gas Ambient on Charge Writing at the LaAlO3/SrTiO3 Heterointerface

We investigated the influences of charge writing on the surface work function (W) and sheet resistance (R) of the LaAlO3/SrTiO3 (LAO/STO) heterointerface in several gas environments: H2(2%)/N2(98%), air, N-2, and O-2. The decrease in W and R due to charge writing was much larger in air (Delta W = -0.45 eV and Delta R = -40 k Omega/S) than in O-2 (Delta W = -0.21 eV and Delta R = -19 k Omega/S). The reduced R could be maintained more than 100 h in H-2/N-2. Such distinct behaviors were quantitatively discussed, based on the proposed chargewriting mechanisms. Such analyses showed how several processes, such as carrier transfer via surface adsorbates, surface redox, electronic state modification, and electrochemical surface reactions, contributed to charge writing in each gas.