Tae Hyoung Moon

Transparent conductive Al-doped ZnO films for liquid crystal displays

Al-doped zinc oxide (ZnO:Al) films were applied to liquid crystal displays (LCDs) as transparent electrodes substituting indium tin oxide (ITO). While the ZnO:Al-based twisted nematic LCD cell showed similar operational behavior to ITO-based counterpart, its electro-optical (EO) and residual dc (r‐dc) characteristics were somewhat improved. Capacitance-voltage relations suggested that these improved EO and r‐dc characteristics of the ZnO:Al-based LCD cell are due to the substantially lower density of charge carrier trapping centers in the polyimide layer∕electrode interface region, demonstrating high application potential of ZnO:Al films as transparent electrodes of LCDs.

Chemical surface passivation of HfO2 films in a ZnO nanowire transistor

The effects of different annealing atmospheres on the chemical surface structure of HfO2 gate dielectric layers have been evaluated in terms of the improvement in the transconductance (gm), current on/off ratio (Ion/Ioff), and carrier mobility (μe) of a back-gated ZnO nanowire field-effect transistor (FET). Compared to O2 and N2 annealed HfO2-gated transistors, the H2 annealed HfO2-gated ZnO nanowire FET exhibited a higher transconductance of 1.77 × 10−7 A V−1, on/off current ratio of ~1.2 × 104, and electron mobility of 11.90 cm2 V−1 s−1.

Correlation of nanochemistry and electrical properties in HfO2 films grown by metalorganic molecular-beam epitaxy

We present the annealing effects on nanochemistry and electrical properties in HfO2 dielectrics grown by metalorganic molecular-beam epitaxy. After the postannealing treatment of HfO2 films in the temperature range of 600–800°C, the thicknesses and chemical states of the films were examined by high-resolution transmission electron microscopy and angle-resolved x-ray photoelectron spectroscopy. By comparing the line shapes of core-level spectra for the samples with different annealing temperatures, the concentrations of SiO and Hf-silicate with high dielectric constant are found to be highest for HfO2 film annealed at 700°C. This result supports that the accumulation capacitance of the sample annealed at 700°C is not deteriorated in spite of a steep increase in interfacial layer thickness compared with that of the sample annealed at 600°C.

PCA-based Neural Network Modeling of MBE-grown HfO 2 Thin Film Characteristics

In this paper, the neural network based modeling for the HfO2thin film characteristics, such as the accumulation capacitance and the hysteresis index, grown by metal organic molecular beam epitaxy was investigated. In order to build the process model, the error back-propagation neural network was carried out and the X-ray diffraction data were used to analyze the characteristic variation for the different process conditions and predict the response models for the electrical characteristics. Principal component analysis was selected to reduce the dimension of the data sets. The compressed data were then used in the neural network. Those initial weights and biases are selected by Latin Hypercube Sampling method. This modeling methodology can allow us to optimize the process recipes and improve the manufacturability.

Effect on the electrical properties of HfO/sub 2/ films grown by metal-organic molecular beam epitaxy

The characteristics of the HfO/sub 2/ dielectric layer on the p-type Si substrate by MOMBE process have been investigated. The electrical properties, surface morphology, and relative concentration of HfO/sub 2/ films could be tuned by O/sub 2//Ar ratio.