Ji-Bong Yu

Easily soluble expanded graphite is synthesized in a one-step exfoliation process that can be used for the lowcost mass production of graphene for various applications because of the simplicity and speed of the process. The graphene obtained is sufficiently expanded to be dispersed in aqueous solutions with an ordinary surfactant and in organic solvents.

The ternary I-III-VI(2) semiconductor of CuInSe(2) nanoparticles with controllable size was synthesized via a simple solvothermal method by the reaction of elemental selenium powder and CuCl as well as InCl(3) directly in the presence of anhydrous ethylenediamine as solvent. X-ray diffraction patterns and scanning electron microscopy characterization confirmed that CuInSe(2) nanoparticles with high purity were obtained at different temperatures by varying solvothermal time, and the optimal tempe

The transport mechanisms in ZnO/CdS/CuInSe2 solar cells prepared by ARCO (now Siemens) Solar Inc. have been analyzed by measurements of current versus voltage at different temperatures in the dark, short-circuit current versus open-circuit voltage at different temperatures in the light, spectral response of quantum efficiency, and junction capacitance. In the dark, recombination in the depletion region and/or thermally assisted tunneling are the dominant transport mechanisms. The observation of

The intrinsic properties of initially p-type doped graphene (grown by chemical vapor deposition (CVD)) can be recovered by buffered oxide etch (BOE) treatment, and the dominant factor governing p-type doping is identified as the H(2)O/O(2) redox system. Semi-ionic C-F bonding prevents the reaction between the products of the H(2)O/O(2) redox system and graphene. BOE-treated graphene field effect transistors (FETs) subsequently exposed to air, became p-type doped due to recovery of the H(2)O/O(2)

Beta-In(2)S(3) nanotubes were synthesized using an organic solution pyrolysis route. The shape of the beta-In(2)S(3) nanotubes was controlled from hexagonal nanoplates to nanotubes simply by changing the reaction time. The growth mechanism of the nanotubes was explained by oriented attachment. The beta-In(2)S(3) nanotubes had a diameter, wall thickness and length of 5.0 nm, 0.79 nm and >10 microm, respectively. The diameter of the beta-In(2)S(3) nanotubes was found to be dependent on the sulfur

Abstract Semi‐ionically fluorinated graphene (s‐FG) is synthesized with a one step liquid fluorination treatment. The s‐FG consists of two different types of bonds, namely a covalent C‐F bond and an ionic C‐F bond. Control is achieved over the properties of s‐FG by selectively eliminating ionic C‐F bonds from the as prepared s‐FG film which is highly insulating (current < 10 −13 A at 1 V). After selective elimination of ionic C‐F bonds by acetone treatment, s‐FG recovers the highly conductive

Dry etching plasma parameters were optimized for texturing single crystalline thin silicon solar cells and hence for high efficiency. In reactive ion etching (RIE) texturing, a low etch depth (∼2 µm) was obtained compared with the etch depth that occurred in the wet chemical texturing process. For the flow ratios (SF6/O2) of 2 and 3, needle-like and cylindrical type structured surfaces were obtained. In the RIE process, the effects of working pressure, flow ratio, and etching time on reflectance