양자점 전자방출특성

Abstract

Quantum dots (QDs) are small devices that contain a tiny droplet of free electrons. Typical dimensions are between nanometers to a few microns. Quantum dots show promise for use in a wide range of applications from the quantum computers of the future, to medical applications, high resolution television screens and household lighting. We studied electron emission properties of quantum dot such as Cadmium selenide (CdSe), Yttrium oxide (Y2O3), Iron (III) oxide (α-Fe2O3). Cadmium selenide (CdSe) is an important Ⅱ-Ⅵ group semiconductor. It is an n-type semiconductor and being developed for use in laser diodes, nanosensors and ii high-efficiency solar cells. CdSe nanoparticles are synthesized and combined with single-walled carbon nanotubes (SWNT). The current measurement of CdSe hybrid is analyzed by conducting-probe atomic force microscopy under laser irradiation (532nm, 655nm). The current is measured by applying a bias voltage of 0.2 V. The current is changed under illumination since SWNTs are hole-transport materials and CdSe particles are n-type semiconductor. We compare the charge transfer between CdSe (or CdSe-pyrene) and SWNT with and without light illumination. The field emission properties of Y2O3-coated single-walled carbon nanotubes (SWNTs) were studied in a vacuum system. Y2O3 films have been deposited on SWNTs by magnetic sputtering. Field emission (FE) was increased more after Y2O3 coating. The field enhancement factor β was calculated from the Fowler-Nordheim equation. We studied about formation and FE property of α-Fe2O3. α-Fe2O3 nanoparticles were formed by the chemical synthesis at room temperature. The field emission properties were studied in a vacuum system. The following X-ray diffraction (XRD), Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are used to characterize nanoparticles structural features.