Improving the CO and CH4 Gas Sensor Response at Room Temperature of α-Fe2O3(0001) Epitaxial Thin Films Grown on SrTiO3(111) Incorporating Au(111) Islands

In this work epitaxial Au islands have been grown on epitaxial α-Fe2O3 thin film by pulsed laser deposition on SrTiO3(111) substrate. Both Au and α-Fe2O3 layer show an island-type growth with an average particle size of 42 and 60 nm, respectively. The crystallographic coupling of lattices is confirmed with a rotation of 30o between the in-plane crystallographic axes of α-Fe2O3 structure and those of SrTiO3(111) substrate and between the in-plane crystallographic axes of Au and those of α-Fe2O3 structure. α-Fe2O3 is the only phase of iron oxide identified before and after its functionalization with Au nanoparticles. In addition, its structural characteristics are also preserved after Au deposition, with minor changes at short-range. The functional character of the complex systems as gas sensor has been proven. Conductance measurements of Au(111)/α-Fe2O3(0001)/ SrTiO3(111) system show that the incorporation of Au islands on top of the α-Fe2O3(0001) layer induces an enhancement of the gas-sensing activity at room temperature for CO and CH4 gas in comparison to a bare α-Fe2O3(0001) layer grown on SrTiO3(111).