Su Ryun Min

Effect of Oxygen Concentration on Properties of Indium Zinc Oxide Thin Films for Flexible Dye-Sensitized Solar Cell

Indium zinc oxide (In2O3–ZnO, IZO) thin films were prepared with variation of oxygen concentration in Ar sputtering gas using rf magnetron sputtering system. Transmittance was greatly improved from 75 to 90% since surface roughness slightly decreased by adding oxygen and low resistivity of 3.28×10-4 Ω cm was achieved at 0.4% oxygen concentration. The performance of dye sensitized solar cell (DSSC) was also studied by fabricating cells with IZO thin films using UV/ozone treatment. According to the results, the efficiency was strongly affected by both transmittance and resistivity of IZO thin films deposited at different oxygen concentrations. Finally, the highest efficiency of 3.11% was achieved from IZO films deposited with 0.4% oxygen concentration, which exhibits a promising application of IZO thin films to flexible DSSC.

Inductively Coupled Plasma Reactive Ion Etching of GeSbTe Thin Films in a HBr/Ar Gas

ABSTRACT Inductively coupled plasma reactive ion etching of GeSbTe (GST) thin films with a photoresist mask was performed using a HBr/Ar gas mixture. The etch rate of GST films increased up to 20% HBr concentration and began to decrease with further increase of HBr concentration. The etch profiles were improved with increasing HBr gas concentration. In particular, clean and vertical etch profiles were achieved at 80∼ 100% HBr gas concentrations. As the coil rf power and dc-bias voltage increased, the etch rates increased. The gas pressure had little influence on the etch rate. The good etch profiles were obtained at high coil power, low dc-bias and high gas pressure. The x-ray photoelectron spectroscopy analysis reveals that Te showed highest reactivity with HBr gas chemistry. A high degree of anisotropic etching of GST films was achieved using HBr/Ar gas mixture at the optimized etch conditions.

Characteristics of Indium Zinc Oxide Thin Films Deposited by Radio Frequency Reactive Magnetron Sputtering for Solar Cells Application

Indium zinc oxide (IZO) thin films were deposited on a glass substrate by radio frequency (rf) reactive magnetron sputtering method. As the rf power increased, the deposition rate and resistivity increased while the optical transmittance decreased owing to the increase of grain size. With increasing gas pressure, the resistivity increased and the transmittance decreased. Atomic force microscopy and scanning electron microscopy were employed to observe the film surface. The IZO films displayed a resistivity of 3.8 × 10-4 Ω cm and a transmittance of about 90% in visible region.

Etch Characteristics of Nickel Oxide Thin Films Using Inductively Coupled Plasma Reactive Ion Etching

Dry etching of NiO thin films masked with a photoresist was performed in a Cl 2 /Ar gas mix. The etch rate of NiO films decreased as Cl 2 concentration increased. The surface morphology etched at high Cl 2 concentration was smoother than that etched at low Cl 2 concentration. The etch profiles were improved with increasing coil radio-frequency (rf) power and dc-bias voltage. An X-ray photoelectron spectroscopy analysis confirms the formation of NiCl 2 compound due to a chemical reaction with chlorine radicals. These results indicate that the etching of NiO films is governed by a physical sputtering etching mechanism with a surface chemical reaction.

HIGH DENSITY PLASMA ETCHING OF IrRu THIN FILMS AS A NEW ELECTRODE FOR FeRAM

ABSTRACT The etch characteristics of IrRu thin films with TiN hard mask were studied using a high density inductively coupled plasma of Cl2/O2/Ar gas mixture. The etch rate and etch profile were investigated by varying the gas concentrations of O2 and Cl2. As the O2 concentration in a 30% Cl2/O2/Ar gas mix increased, the etch selectivity of IrRu to TiN increased, resulting in the vertical etch profile. As the Cl2 concentration increased, the etch profile became worse due to the low etch selectivity. It was revealed that the etch selectivity of IrRu to TiN was closely related to the etch profile. The residue-free IrRu etching with a high degree of anisotropy was achieved using the Cl2/O2/Ar mixture at the optimized etching conditions.