Jung-Min Cho

Preparing of CIGS nanopartcles and thin films by one step non-vacuum deposition methods

The CIGS (Cu(InGa)Se2) thin films were successfully synthesized by using non-vacuum deposition methods. Those methods were nanoparticle-precursor deposition and non-vacuum spray deposition. The synthesized CIGS thin films had typical characteristics of CIGS for absorber layer. The structures of CIGS thin films were chalcopyrite and the properties of thin films were dense and smooth. The microstructure of CIGS thin films were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), uv-vis spectroscopy.

Vertical Growth and Morphology Control of Zinc Oxide Micro Rod

It was tried to fabricate a template substrate having a 3-dimensional structure with micrometer- size diameter in order to extend the p-n junction area of the compound thin film solar cell. The ZnO micro rod layer, which was grown vertically by using the chemical bath deposition, was successfully fabricated as a hexagonal shape along the c-axis which is the preferred growth orientation. The growth of ZnO rod being adequate for device applications was examined through investigating growth mechanism of ZnO rod and optimizing the photo resist profile so as to remove the undercut which was found in the grown ZnO rod. The growth model and material properties of the 3-dimensional ZnO rod were analyzed through the scanning electron microscope.

The Effect of Post-Deposited Na on Cu(Inx,Ga1-x)Se2 Solar Cells by using the Na2S Solution

It is known that even mixing only a small amount of Na has effect on electrical and structural property of the CIGS absorber layer and, as a result, device efficiency is improved. In this study, unlike the conventional method where Na diffuses from SLG while CIGS absorber is growing, a new method was applied. In the new method, Na precursor is deposited on the CIGS absorber layer grown on Al2O3/SLG to incorporate Na. The effect of Na on the absorber layer was observed using secondary ion meass spectroscopy, Hall measurement system, scanning electron microscopy, and x-ray diffraction. As a result, it was found that, in the post deposition treated CIGS absorber layer, Na has effect mostly on the electrical property of CIGS without significant change of the microstructure.

Growth of CuInSe 2 Thin Film Using Non-Vacuum Solution Deposition Technique

Polycrystalline thin films of CuInSe 2 were prepared successfully using the chemical spray pyrolysis technique as a function of Cu/In atomic ratios and variation of selenium ratios. For the compositional and structural analysis, X-ray diffraction, UV-visible spectroscopy, the Hall effect measurement and scanning electron microscopy were carried out. The effects of the Cu/In ratio and selenium concentration were observed in the XRD, SEM, UV-visible spectrum and the Hall effect measurement analysis for fabricated thin films. The result of XRD and UV-visible analysis showed an increase or decrease of crystallinity and shift of transmittance tendency depending on the copper and selenium content. The grain size of thin films was increased with the increase of copper content. In the thin films, the variation of Cu/In ratios between 0.8 to 1 showed an increase on hole density, but a decrease of Hall mobility and resistivity. We suggest the formation of Cu x Se phase particles or layers depends on the spray solution. Based on these results, we will fabricate and characterize CISe/CIGSe thin film solar cells in further work.