Variable resistor made by repeated steps of epitaxial deposition and lithographic structuring of oxide layers by using wet chemical etchants

Variable resistors were constructed from epitaxial SrRuO3 (SRO), La0.67Sr0.33MnO3 (LSMO) and SrTiO3 layers with perovskite crystal structure. Each layer was patterned separately by lithographic methods. Optimized wet chemical etchants and several polishing steps in organic solvents allowed good epitaxy of subsequent layers, comparable to epitaxy on pristine substrates. Periodate as the oxidizing agent for SRO and iodide with ascorbic acid as the reducing agents for LSMO were used to attack these chemically resistant oxides. The final devices changed their conductance in a similar manner to previously described variable resistors that were defined with shadow masks.

► A variable resistor was constructed from epitaxial oxide layers.
► Each layer was structured individually by lithographic methods.
► Wet chemical etchants for SrRuO3 and La0.67Sr0.33MnO3 were developed and optimized.
► The epitaxial layers grew in high quality on the chemically etched surfaces.