Lithography on GaMnAs layer by AFM local anodic oxidation in the AC mode

The results on the local anodic oxidation (LAO) by conductive coated tip of an atomic force microscope (AFM) are presented. AFM LAO with modulated voltage (AC mode) on thin GaMnAs layer is performed. Oxide lines produce potential barrier capable to make narrow constrictions for charge carriers. Oxide line height dependence on various parameters of the oxidation process is studied. Improvement in the homogeneity and reproducibility of oxide lines is observed. Lines up to 30 nm high are obtained. Magnetotransport measurement on constricted samples is realized.