A COMPARATIVE STUDY OF ERBIUM OXIDE AND GADOLINIUM OXIDE HIGH-K DIELECTRIC THIN FILMS GROWN BY LOW-PRESSURE METALORGANIC CHEMICAL VAPOUR DEPOSITION (MOCVD) USING β-DIKETONATES AS PRECURSORS

摘要

In this paper, a comparative study of thin films of Er_2O_3 and Gd_2O_3 grown on n-type Si(100) by low-pressure metalorganic chemical vapour deposition (MOCVD) under the identical conditions has been presented. p-Diketonate complex of rare earth metals was used as precursor. Description on the evolution of the morphology, structure, optical, and electrical characteristics of films with respect to growth parameters and post-deposition annealing process has been presented. As-grown Gd_2O_3 films grow with <111> texture, whereas the texture of Er_2O_3 films strongly depends on the growth temperature (either <100> or <111>). Compositional analysis reveals that the Gd2O3 films grown at or above 500℃ are carbon free whereas Er_2O_3 films at upto 525℃ show the presence of heteroatoms and Er_2O_3 films grown above 525℃ are carbon free. The effective dielectric constant is in the range of 7-24, while the fixed charge density is in the range - 10~(11) to 10~(10) cm~(-2) as extracted from the C-V characteristics. DC Ⅰ-Ⅴ study was carried out to examine the leakage behaviour of films. It reveals that the as-grown Gd_2O_3 film was very leakey in nature. Annealing of the films in oxidizing ambient for a period of 20 min results in a drastic improvement in the leakage behaviour. The presence of heteroatoms (such as carbon) and their effect on the properties of films are discussed.