Properties and Characterization of ALD Grown Dielectric Oxides for MIS Structures

Abstract

We report on an extensive structural and electrical characterization of undergate dielectric oxide insulators Al 2 O 3 and HfO 2 grown by atomic layer deposition. We elaborate the atomic layer deposition growth window for these oxides, finding that the 40-100 nm thick layers of both oxides exhibit fine surface flatness and required amorphous structure. These layers constitute a base for further metallic gate evaporation to complete the metal-insulator-semiconductor structure. Our best devices survive energizing up to 3 MV/cm at 77 K with the leakage current staying below the state-of-the-art level of 1 nA. At these conditions the displaced charge corresponds to a change of the sheet carrier density of 3 10 13 cm -2 , which promises an effective modulation of the micromagnetic properties in diluted ferromagnetic semiconductors.