Properties and Characterization of ALD Grown Dielectric Oxides for MIS Structures

摘要

We report on an extensive structural and electrical characterization of undergate dielectric oxide insulators Al2O3 and HfO2 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 x 1013 cm"2, which promises an effective modulation of the micromagnetic properties in diluted ferromagnetic semiconductors.