Nondestructive cleaning of the LaAlO3/SrTiO3 surface with ultraviolet light and ozone.

The effect of ultraviolet light produced ozone and irradiation (UV/ozone) cleaning on the surface properties and interface electrical properties of 4 unit cell (uc) LaAlO₃/SrTiO₃ samples is examined. A standard photolithography process is used to contaminate the samples which are then cleaned in UV/ozone. Atomic force microscopy measurements show that the photoresist contaminated samples can be cleaned efficiently using this method. The surface roughness of the cleaned samples is comparable to that of the as-grown samples. Furthermore, electrical transport measurements show that the mobility decreases and the sheet carrier density increases for the contaminated samples, which also display indications of an onset to the Kondo effect. By removing the contaminants with UV/ozone cleaning, the mobility and sheet carrier density can be partially restored toward the as-grown values. The mobility is increased by about two times from ≈1000 cm² V^-1 s^-1 for the contaminated samples to ≈2000 cm² V^-1 s^-1 for the ozone cleaned ones. [ABSTRACT FROM AUTHOR]