에너지하베스팅소자 적용을 위한 구리셀레늄 박막 특성

Abstract

Yong-Seok Lee Advisor : Prof. Nam-Hoon Kim, Ph. D. Department of Electrical Engineering Graduate School of Chosun University Technology advancement has led to a progressive increase in the number of smart wearables available and an increase in the complexity of the functions they can perform. Energy harvesting involves transforming ambient energy into electric power, reducing reliance on the battery of wearables and enhancing overall energy efficiency. Energy harvesting technology is crucial because smart wearables need a constant power source. Smart wearables are intelligently designed for daily wear by applying wearable technology. It is developed to be worn directly on the body or integrated into clothing and accessories. Copper selenides (Cu-Se) are important members of the first-row transition metal chalcogenides. These are a family of inorganic compounds that contain a transition metal and a chalcogen (oxygen, sulphur, selenium, or tellurium). These materials are promising candidates for a wide range of technological applications due to their wide range of elec-trical and optical properties. Characteristics of Cu-Se Thin Films for Energy-Harvesting Devices In this thesis, p-type Cu-Se thin films were deposited on glass substrates at room temperature using radio frequency magnetron sputtering by single multi-component CuSe2 target. The impact of sputtering power on the homogeneity and stoichiometry of the thin films across their thickness, secondarily affecting their electrical and optical properties, was investigated. Systematic characterization of the Cu-Se thin films, including morphology, microstructure, chemical composition, and depth-directional chemical bonding state and defect structure of the thin films, revealed that the sputtering power played an important role in the homogeneity and stoichiometry of the thin films. At very low and very high sputtering power levels, the Cu-Se thin films exhibited more deviations from stoichiometry, while an optimized sputtering power resulted in more homogenous thin films with improved stoichiometry across the entire thin-film thickness, despite showing Se deficiency at all depths. The electrical and optical properties of the Cu-Se thin films, correlated with their stoichiometry and potential defects, were studied to determine the nature of defects in the deposited films under varying sputtering power conditions and their correlation with the band gap and elemental ratio at different depths of the films. The homogeneity of the film across the depth, as well as the composition of the entire thin film, should be considered in designing the energy-harvesting thin film devices.