Jina Jeon

Reduction in crystallographic tilting of lateral epitaxial overgrown GaN by removal of oxide mask

The lateral overgrowth of GaN was carried out by low-pressure metalorganic chemical vapor deposition. SiO2 mask was removed just before coalescence and a subsequent lateral overgrowth was carried out to complete the fabrication of a SiO2-removed lateral epitaxial overgrown (LEO) GaN layer. The crystallographic tilting of (0002) plane, that was apparent in our standard LEO GaN layers, was absent in SiO2-removed LEO layer and x-ray diffraction measurement indicated a superior crystallinity for the SiO2-removed LEO layer. These results are attributed to the elimination of the interface between oxide mask and laterally grown GaN layer. The reduced crystallographic tilting in SiO2-removed LEO GaN layer also enhanced the quality of the coalesced fronts, as determined from cathodoluminescence images.

Inversion domains triggering recovery of luminescence uniformity in epitaxially lateral overgrown thick GaN film

A 150 μm-thick GaN layer was grown by halide vapor phase epitaxy utilizing selective lateral overgrowth on a SiO2-prepatterned sapphire substrate. A series of optically active regions above the SiO2 mask was observed in cross sectional monochromatic cathodoluminescence images taken at 367 nm. These bright regions were, however, consistently terminated by triangular shaped domains at 60 to 80 μm thickness, leaving no sign of luminescence nonuniformity beyond the thickness. In conjunction with the recent results on the characteristics of inversion domains in GaN, we proposed that these triangular regions might be inversion domains.

Effects of lateral overgrowth on residual strain and In incorporation in a-plane InGaN/GaN quantum wells on r-sapphire substrates

We investigated the effects of the patterned lateral over-growth on the residual strain in GaN templates and In incorporation in a-plane InGaN/GaN quantum wells grown on a r-sapphire substrate, by utilizing micro-photoluminescence and Raman scattering spectroscopy. Strong enhancement of emission intensity is observed from the wing area. We report a reduction in the residual strain and different In incorporation in the wing area. The InGaN quantum wells on the merged area have higher In composition with smaller residual strain of the GaN layers underneath.

Measurement of Cosmic-Ray Nuclei with the Third Flight of the CREAM Balloon-Borne Experiment

The balloon-borne Cosmic Ray Energetics And Mass experiment had its third flight (CREAM-III) over Antarctica for 29 days from December 17, 2007 to January 19, 2008. CREAM-III was designed to directly measure the elemental spectra of cosmic-ray nuclei from Hydrogen to Iron in the energy range from 10^12 to 10^15 eV. Energy of incident cosmic rays was measured with a calorimeter that consisted of a densified carbon target directly above a stack of 20 alternating layers of tungsten and scintillating fiber ribbons. Multiple charge measurements were independently made with the silicon charge detector (SCD), Cherenkov Camera (CherCam), and a Timing Charge Detector (TCD) in order to identify particles and minimize backscattering effects from the calorimeter. Compared to previous CREAM flights, the electronic noise of CREAM-III was reduced, significantly lowering the energy threshold. Results from on-going analysis of the energy spectra will be presented.

Measurements of the Proton and Helium Spectra from CREAM-V

The Cosmic Rays Energy And Mass (CREAM) balloon payload directly measures the composition and elemental spectra of cosmic rays in the upper stratosphere. It is designed to probe the acceleration mechanism and propagation history of cosmic rays at energies from 10

Performance of the ISS-CREAM Calorimeter

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Effect of oxygen incorporation in a-plane GaN on p-type ohmic contact property

up to 10

Rapid relaxation of crystallographic anisotropy in SiO2-removed lateral epitaxial overgrown GaN layers

^{15}

Effect of rapid thermal annealing on GaN damages induced by electron cyclotron resonance reactive ion etching

eV. Being the fifth flight in a series of seven, CREAM-V took data above Antarctica for 39 days from December 1

A selective growth of III-nitride by MOCVD for a buried-ridge type structure

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