Kyoung Suk Oh

A study on the formation and characteristics of the SiOCH composite thin films with low dielectric constant for advanced semiconductor devices

The SiOCH composite thin films were deposited on a p-type Si(100) substrate using bis-trimethylsilane (BTMSM) and O2 mixture gases by an inductively coupled plasma chemical vapor deposition (ICPCVD). High density plasma of approximately ∼1012 cm−3 is obtained at low pressure (<320 mtorr) with an RF power of approximately 300 W in the inductively coupled plasma source where the BTMSM and oxygen gases are greatly dissociated. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra show that the film has SiCH3 and OH related bonds. The CH3 groups formed the void in the film and the Si atoms in the annealed sample have different chemical states from those in the deposited sample. It means that the void is formed due to the removing of OH related bonds during the annealing process. The relative dielectric constant of the annealed sample with the flow rate ratio O2/BTMSM as 0.3 at 500°C for 30 min is approximately 2.5.

High-Temperature–Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells

Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm2 active area and 18% over a 1 cm2 active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

Formation and characterization of the fluorocarbonated-SiO2 films by O2/FTES-helicon plasma chemical vapor deposition

Abstract Fluorocarbonated-SiO 2 films were prepared on a p-type Si(100) substrate using FSi(OC 2 H 5 ) 3 (FTES) and O 2 mixture gases by a helicon plasma source. High density O 2 /FTES/Ar plasma of ∼10 12 cm −3 is obtained at low pressure ( 2 gases are greatly dissociated. The fluorocarbonated-SiO 2 film deposited in the helicon plasma chemical vapor deposition contains C–F bonds which are not found in the fluorocarbonated-SiO 2 film made by thermal chemical vapor deposition, where the FTES and O 2 react chemically on the substrate. Fourier transform infrared and X-ray photoelectron spectroscopy spectra show that the film has Si–F, Si–O, and C–F bonds. The Si–F and C–F bonds may lower the dielectric constant greatly. The relative dielectric constant, leakage current density, and dielectric breakdown voltage are about 2.8, 8×10 −9 A/cm 2 , and > 12 MV/cm, respectively. However the dielectric constant and leakage current density of the film annealed at 500°C are about 3.2 and 9×10 −11 A/cm 2 , respectively. The step-coverage of the deposited fluorocarbonated-SiO 2 film in 0.3 μm metal pattern is about 91%.

Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively.

Development of Plasma-Damage Free Neutral Beam Sputtering System; High Performance Indium Tin Oxide Films at Room Temperature with Application to Top Emmission OLED

A neutral beam system has been developed to produce hyperthermal neutral beams (HNB) sputtering system. ITO thin film with good performance has been developed by the HNB sputtering system at the room temperature. The optimized conditions as neutral beam acceleration bias of -30 V and In & Sn composition ratio of 99:01 gives lower resistivity as 4.22 times 10-4 Omega-cm and higher transmittance over 90% near wavelength of 550 nm. The room temperature-processed ITO films applied top electrode of OLED without plasma related damage.

Formation and characteristics of the Si-O-C-H composite films with low dielectric constant deposited by O/sub 2//BTMSM-ICPCVD

Si-O-C-H composite films were deposited using a radio frequency inductively coupled plasma chemical vapor deposition (ICPCVD) system with a BTMSM precursor and oxygen gases. FTIR spectroscopy and XPS spectra were used to investigate the bonding configurations such as Si-O-Si, Si-O-C and Si-CH/sub 3/ bonds in the films. From the changes in the FTIR and XPS spectra between the as-deposited and annealing film, we infer that the attachment of the Si-O-Si ring link with CH/sub 3/ groups is useful for forming a nano-sized void in the film. It can be explained to obtain a lower dielectric constant (k=2.3).