Surface patterned dielectrics by direct writing of anodic oxides using scanning droplet cell microscopy

•Scanning droplet cell microscopy was applied for local gate oxide writing.•Sharp lines are obtained at the highest writing speed of 1mmmin−1.•13.4kCcm−3 was found as charge per volume for aluminium oxide.•High field constant of 24nmV−1 and dielectric constant of 12 were determined for Al2O3 by CV and EIS.