Kelvin Probe Force Microscopy Study of LaAlO3/SrTiO3 Heterointerfaces
Surface potential distributions in ultra-thin (0.8–3.9 nm) LaAlO3 layers deposited on SrTiO3 substrates are studied. It is found that the potential distribution evolves from island-like to a homogeneous one with increasing LaAlO3 thickness. It is suggested that the observed islands are caused by a locally enhanced concentration of mobile charge carriers at the interface that is, in turn, related to non-stoichiometry of the layers with thickness bellow 4 unit cells. Transition to a homogeneous potential distribution with increasing LAO thickness (≥4 unit cells) corresponds to the formation of a quasi-2-dimensional electron gas. The results agree with a percolation model explaining the insulator-to-metal transition that occurs at the LaAlO3/SrTiO3 heterointerface.
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Document Type: Research Article
Publication date: April 1, 2010
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- Journal of Advanced Microscopy Research (JAMR) provides a forum for rapid dissemination of important developments in high-resolution microscopy techniques to image, characterize and analyze man-made and natural samples; to study physicochemical phenomena such as abrasion, adhesion, corrosion and friction; to perform micro and nanofabrication, lithography, patterning, micro and nanomanipulation; theory and modeling, as well as their applications in all areas of science, engineering, and medicine.
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