Myungki Jung

Properties of CdTe/InSb heterostructures grown by temperature gradient vapor transport deposition

Abstract Heteroepitaxial films of CdTe were grown by a simple method of temperature gradient vapor transport deposition in InSb(1 1 1) orientation substrates in the growth temperature range between 180°C and 280°C. Double crystal X-ray diffraction was used to evaluate the crystal quality of the CdTe epitaxial films. The full width at half-maximum intensity of the double crystal diffraction CdTe peak was as small as 30 arcsec. Room temperature capacitance-voltage measurements showed the nominally undoped CdTe layers to be n -type with N d  N a in the low 10 16 cm −3 region and excellent confinement of electrons at the CdTe/InSb heterointerfaces. Photoluminescence measurements at 15 K showed that the CdTe film grown on InSb(1 1 1) at 230°C appeared to have strong and sharp exciton transitions and weak defect-related bands.

Elastic strain effects dependence on the energy band gaps and the lattice parameters in CdTe epitaxial layers on GaAs (100) substrates grown by hot wall epitaxy

Abstract Electrolyte electroreflectance spectroscopy and X-ray diffraction measurements on CdTe/GaAs strained heterostructures grown by hot wall epitaxy were carried out to investigate the effect of the elastic strain dependence on the energy band gaps and the lattice parameters. Biaxial compressive strains existed in CdTe layers thinner than 3 μm. This critical thickness was the smallest value for any CdTe/GaAs heterostructures previously grown by hot wall epitaxy. The results from electrolyte electroreflectance spectroscopy and X-ray diffraction were in good qualitative agreement with each other.

Development of micro-objective lens array for large field-of-view multi-optical probe confocal microscopy

We describe multi-optical probe confocal microscopy using a micro-objective lens array for large areal inspection. A microlens array with 100??m focal length, 80??m diameter and 90??m pitch was designed and fabricated with an array size of 10???10. In order to produce the high-fidelity microlens array, a UV imprinting process was employed, and a UV transparent mold for the imprinting process was manufactured by replicating a reflow lens master. A blocking filter between the microlenses was introduced to minimize crosstalk and stray light noise for high resolution and high contrast imaging. The developed system is characterized by a 1?mm???1?mm field of view with a nano-stage with 100??m travel length. The lateral resolution was measured to be 0.79??m. The method can be used for various applications such as the inspection of electric devices including display panels and large-area printed circuits with a high resolution.

Development of optical system with rotational misalignment adjustment for multi-optical-probe confocal microscopy

Optical scanning confocal microscopy enables high-resolution imaging and optical sectioning for three-dimensional imaging. Technologies to improve confocal microscopy are being developed for applications, such as real-time bioinspection, fluorescence sample imaging, and ultra-high-resolution measurement. Recently, the need for high-resolution large-area inspection of electronics has been increasing rapidly, including large-area display panels. Therefore, the authors constructed an optical system for multi-optical-probe confocal microscopy. A 10 × 10 micro-objective-lens array was fabricated with high fidelity using an ultraviolet nanoimprinting process. To investigate the utility of this system, 1 × 1 mm2 images were examined using an XY-translation nanostage scanning with a travel length of 100 μm.

Structural and optical properties of CdIn2Te4 films on p-InSb(1 1 1) grown by temperature gradient vapor transport deposition

Abstract CdIn 2 Te 4 epitaxial films were grown on p -InSb(1 1 1) orientation substrates by temperature gradient vapor transport deposition via a two-step method. Double crystal X-ray diffraction was used to evaluate the crystallization and the crystal quality of the CdIn 2 Te 4 films. Raman spectroscopy showed several optical phonon modes of the CdIn 2 Te 4 thin films. The stoichiometry of the CdIn 2 Te 4 films was investigated by Auger electron spectroscopy. The results showed that high quality epitaxial films of CdIn 2 Te 4 could be grown on p -InSb(1 1 1) by a simple technique.

Acoustically sticky topographic metasurfaces for underwater sound absorption

A class of metasurfaces for underwater sound absorption, based on a design principle that maximizes thermoviscous loss, is presented. When a sound meets a solid surface, it leaves a footprint in the form of thermoviscous boundary layers in which energy loss takes place. Considered to be a nuisance, this acoustic to vorticity/entropy mode conversion and the subsequent loss are often ignored in the existing designs of acoustic metamaterials and metasurfaces. The metasurface created is made of a series of topographic meta-atoms, i.e., intaglios and reliefs engraved directly on the solid object to be concealed. The metasurface is acoustically sticky in that it rather facilitates the conversion of the incident sound to vorticity and entropy modes, hence the thermoviscous loss, leading to the desired anechoic property. A prototype metasurface machined on a brass object is tested for its anechoicity, and shows a multitude of absorption peaks as large as unity in the 2-5 MHz range. Computations also indicate that a topographic metasurface is robust to hydrostatic pressure variation, a quality much sought-after in underwater applications.

The effect of nano grating shapes on the sensitivity of guided mode resonance protein sensor fabricated by nano injection molding process

We investigated the effect of nano grating shapes on the sensitivity of nano injection molded guided-mode-resonance protein sensor. To confirm the profile effects, we performed design, fabrication and performance evaluation.