원자층 증착법으로 증착한 산화아연 반도체 : 특성분석과 응용

Abstract

Zinc oxide (ZnO) with wideband gap (3.37 eV), as an important functional oxide, has been actively studied due to its excellent chemical/electrical/optical properties and the ease of growth of nanostructures applicable to the nanoscale functional devices such as sensor, solar cell, light emitting diode, and ultraviolet laser. For these various applications, it is important to control the electrical and optical properties of ZnO thin films. ZnO is well known to be an n-type semiconductor due to intrinsic electron donor defects such as oxygen vacancy, VO, and/or zinc interstitial, Zni. Therefore, the adjustment in the intrinsic defects of ZnO plays an important role to change in characteristics of ZnO. In this study, ZnO thin film was deposited under various process temperatures from 50℃ to 250℃ to verify changes of the film properties as a function of the process temperature. Atomic layer deposition (ALD) method was used to deposit films at low temperatures in a controlled manner by the alternate exposure of precursors and reactant gases with self-limiting surface reactions. ALD method can deposit high quality films at relatively low temperatures with accurate thickness control, good uniformity and conformality, therefore it is good for fabricating the devices which demand low temperature processes. These ALD ZnO films were investigated, and their physical and electrical properties at various process temperatures were compared to determine the proper process temperature ranges for the creation of active channel layers and transparent conducting oxide layers for downstream applications in transparent electronic devices. Additionally, the study of ALD ZnO films extended to three dimensional ZnO nanostructures over two dimensional ZnO films. Nanostructured materials are defined as those whose structural element – cluster, crystallites or molecules – have dimension in the 1 to 100 nm range. These nano size materials exhibit novel/significantly improved physical/chemical and biological properties which is not found in bulk or micro sized film. In order to use the proper these nanostructure in the suitable applications, it is important to control features such as their diameter, density, and shape. Through this study, it is investigated to control nanostructure parameters by means of ALD ZnO film. And the fucntionalization of ZnO nanostructure were demonstrated by using ALD that offers high uniform film even on complex three dimensional structure