Seon Pil Kim

Improvement of charge storage characteristics on floating gated nonvolatile memory devices with In2O3 nanoparticles embedded polyimide gate insulator

Nanofloating gate memory (NFGM) devices using In2O3 nanoparticles as charge storages embedded in polyimide gate insulator were fabricated. Self-assembled In2O3 nanoparticles were formed inside the polyimide matrix as a result of chemical reactions between indium ions and polymer precursors. The average diameter and the particle density were 7nm and 6×1011cm−2, respectively. The memory window of fabricated NFGM device due to the charging effect of In2O3 particles was larger than 4.4V. The charge storage characteristics of NFGM devices with In2O3 nanoparticles embedded in polyimide gate insulator were significantly improved by the postannealing in a 3% diluted hydrogen in N2 ambient.

Band gap modulation of ZnTe1-xOx alloy film by control of oxygen gas flow rate during reactive magnetron sputtering

The band gap energy of ZnTe1-xOx alloy films grown on c-plane sapphire substrates was modulated by controlling the argon-oxygen ratio during radio frequency magnetron sputtering. The ZnTe1-xOx samples were deposited at a substrate temperature of 200 °C and with gas mixtures of 2%–8% oxygen in argon. The optical transparency of the ZnTe1-xOx samples was measured in the 1.5–6.0 eV energy range by optical transmission spectra. The optical band gap, obtained from plots of (αhν)2 as a function of hν, increased from 2.2 to 4.9 eV with increasing oxygen ratio, believed to be a result of a change in bonding structure through composition exchange during film deposition by reactive magnetron sputtering. These results show that the band gap energy of ZnTe1-xOx, ZnOTeO, and (ZnO)1-x(TeO2)x alloy films can be modulated, making them more suited for applications as windows and as active layers for ZnTe-based intermediate band solar cells.

Fabrication of Low Temperature Polycrystalline Silicon Thin-Film Transistor Nonvolatile Memory Devices for Digital Memory on Glass Applications

We fabricated the nano-floating gate memory (NFGM) devices on the polycrystalline silicon (poly-Si) films crystallized by excimer laser annealing (ELA) method for thin-film transistor liquid-crystal display (TFT-LCD) with a new integration technology called digital memory on glass (DMOG). The In2O3 nano-dots were formed in polyimide gate insulating layers at low temperature as the charge storages of nonvolatile memory for DMOG applications. The memory window of low temperature poly-Si TFT nonvolatile memory with In2O3 nano-dots embedded in polyimide was larger than 3.2 V and the memory characteristics were considerably improved by 3% hydrogen diluted N2 ambient annealing.

Electrical Characteristics of TiSi2 Nanocrystal Nonvolatile Memory with Barrier-Engineered Tunnel Layer

In this study, we fabricated TiSi2 nanocrystal nonvolatile memory devices with silicon nitride–oxide–nitride (NON) and SiO2 tunnel barriers. The TiSi2 nanocrystals with diameters of 2–5 nm and a density of 1.5 ×1012 cm-2 were formed using radio frequency magnetron sputtering in argon and a postannealing process. The memory effect of the TiSi2 nanocrystal memory device with the NON tunnel barrier was observed at about 0.7 V at 100 ms when the applied program/erase voltages were +7 V/-7 V. Also, the memory window of the NON tunnel barrier device was maintained up to 1.3 V after 103 s. These results indicate that the NON tunnel barrier provides an effective tunneling thickness for the fast program/erase speeds and an adequate physical thickness for long charge retention characteristics in nonvolatile memory devices.

Emission enhancement of InGaN/GaN light emitting diode by using Ag nanoparticles.

We have studied the effect of surface plasmon (SP) coupling to enhance emission efficiency of light emitting diode (LED) with multiple quantum wells (MQWs) structure by positioning Ag nanoparticles on the line-arrayed patterns. The line-arrayed patterns were fabricated by photolithography and inductively coupled plasma reactive ion etching process. The Ag nanoparticles were formed by thermal annealing at 300 degrees C and 400 degrees C for 30 min for Ag films with thickness of 10 nm and 15 nm deposited on the patterned LED structures, respectively. The photoluminescence (PL) emission intensity of line-patterned LED with Ag nanoparticles was overall enhanced. According to the spectra of time resolved PL, carrier life times of line-patterned LED with and without Ag nanoparticles appeared about 0.47 and 5.47 ns, respectively.

Field enhancement effect by multi‐tunnel layer in metal‐silicide nanocrystals nonvolatile memory

Nonvolatile memory devices with TiSi2 and WSi2 nanocrystals on the SiO2/Si3N4/SiO2 (ONO) and Si3N4/SiO2/Si3N4 (NON) tunnel layers were fabricated and their electrical properties were characterized. For the WSi2 nanocrystals memory, the threshold voltage shift (ΔVTH) maintained about 1.3 V at 125 °C, when program/erase (P/E) speeds were 50 ms. After P/E at ±7 V for 100 ms, ΔVTH of the TiSi2 memory with NON tunnel layer was about 0.7 V, while ΔVTH of the WSi2 memory with ONO tunnel layer was approximately 1 V after applied P/E pulse at ±8 V for 50 ms.

Study on transparent and flexible memory with metal‐oxide nanocrystals

A memory device with the In2O3 nanocrystals embedded in biphenyl‐tertracarboxylic dianhydride‐phenylen diamine (BPDA‐PDA) polyimide layer was fabricated, and its electrical and optical properties were evaluated. The In2O3 nanocrystals showed an irregular spherical shape with the average size and density of about 7 nm and 6×1011 cm−2, respectively. In the structure of BPDA‐PDA polyimide/In2O3 nanocrystals/ZnO/ITO/sapphire, a current bistability by difference resistance appeared in the sweep voltage rage from −7 V to 7 V. Then, the transmittance efficiency of this was measured about 80 % between 440 nm to 800 nm by the ultraviolet‐visible transmittance spectra.

Electrical Characterization of Nano-Floating Gated Silicon-on-Insulator Memory with In2O3 Nano-Particles Embedded in Polyimide Insulator

We fabricated the floating gate for silicon-on-insulator nonvolatile memory devices with In2O3 nano-particles embedded in polyimide insulator. Self-assembled In2O3 nano-particles were created by chemical reaction between the biphenyl dianhydride-p-phenylenediamine polymer precursor and indium films. The particles size and density of In2O3 nano-particles were 7nm and 6×1011cm-2, respectively. The current-voltage and retention time of fabricated device were characterized by using semiconductor parameter analyzer. A significant threshold voltage shift of fabricated nano-floating gate memory devices obtained, because of the charging effects of In2O3 nano-particles. And a memory window measured about 1V at initial status.