Dong-joon Ma

Two-dimensional photonic crystal color filter development

Reflective color filters using two-dimensional photonic crystals based on sub-wavelength gratings were proposed and constructed. Using low-cost nanoimprint lithography, an amorphous silicon layer was deposited through the low-temperature PECVD process and patterned into two-dimensional structures. The isolated amorphous silicon patterns were readily crystallized using a multi-shot excimer laser annealing at low energy. A study of the close relationship between color filter reflectance and silicon pattern crystallinity is introduced. Theoretical and experimental results show that the proposed color filters have high reflectance and, moreover, decrease the dependence on incident angle compared to one-dimensional photonic crystal color filters.

Low temperature crystallization of high permittivity Ta oxide using an Nb oxide thin film for metal/insulator/metal capacitors in dynamic random access memory applications

(Ta1−xNbx)2O5 as the dielectric for metal/insulator/metal capacitors with Ru electrodes were investigated. Deposition was performed by ALD using tantalum ethoxide, niobium ethoxide, and ozone as source materials. The high-κ dielectric layer was synthesized from a binary layer (Ta2O5∕Nb2O5) with self-diffusion of the seed layer, Nb2O5. The seed layer becomes effective at a thickness of over 60 A. The dielectric deposited with 60 A Nb2O5 crystallized at 575 °C, the lowest processing temperature required to achieve good step-coverage (86%) for future generation dynamic random access memory. A capacitance density of about 23.0fF∕μm2 was observed for seed layers of 20 and 35 A. Capacitors with a Nb2O5 seed layer of 60 A achieved a capacitance density as high as 44.2fF∕μm2. The reason for this disparity is that the thicker insulator crystallizes at a post-annealing temperature of 575 °C. The leakage current measured at 1 V was moderately low, near 1×10−7A∕cm2.

Characterization of the Sn Doped In2O3 Film Prepared by DC Magnetron Sputter Type Negative Metal Ion Beam Deposition

Transparent conducting indium tin oxide (ITO) films were prepared on a glass substrate by DC magnetron sputter type negative ion source from a target of a mixture of In2O3 (90%) and SnO2 (10%). In order to investigate the influence of cesium (Cs) partial pressure (PCs) on the optoelectronic property of ITO films, the PCs was varied from 1×10-3 to 2.2×10-3 Pa. The O2/Ar flow rate, working pressure, power density, and substrate temperature were kept constant at 3.6%, 9×10-2 Pa, 2.5 Wcm-2 and 70°C, respectively. By optimizing the PCs at 1.7×10-3 Pa, transparent (transmission ~81% at 550 nm) and conducting (resistivity ~4.3×10-4 Ωcm) ITO films were prepared. Atomic force microscopy (AFM) images showed that the surface morphology also varied significantly with PCs and that the lowest surface rms roughness was 0.6 nm measured at PCs=1.7×10-3 Pa. XPS measurement showed that the Cs concentration in the ITO films was less than 0.2 at%.

P‐57: Study on the Wet Processable Antimony Tin Oxide (Transparent Conducting Oxide, TCO) Using Anode for PLED Device Instead of ITO

In this study, fabricated a PLED device by using the wet processable Antimony Tin Oxide(ATO) as the transparent electrode instead of the Indium Tin Oxide (ITO) and measured its electrical and optical characterization. By controlling annealing temperature and thickness of the ATO, 90% or more of visible region transparency and sheet resistance of 30Ω/°C was obtained.