380keV proton irradiation effects are investigated on p-GaN and n-GaN layers in GaN-based light emitting diode (LED) by characterizing current-voltage (I-V) characteristics of p-n junction, and two-terminal resistance of p- and n-GaN on both type of layers in LED wafer. Two-terminal resistance on n-GaN kept its initial value after the 1×1014cm-2 fluence, and was remained the same order after the 1×1015cm-2 fluence. On the other hand, p-GaN showed sensitive increase in two-terminal resistance after the 1×1014cm-2, and six orders of increase after the 1×1015cm-2 fluence. Observed sensitive increase of resistivity in p-GaN is explained as a lower initial hole density in p-GaN than the initial electron density in n-GaN layer.

Effects of electron beam irradiation at 15 keV on graphene are investigated by optical and electron characterization using Raman and two-terminal resistance measurement and photoconductivity measurement. In Raman spectra, increase of defects in D-peak to G-peak ratio by increase of electron irradiation by 70 mC/cm2 was found. Resistance of graphene showed an increase after the irradiation. Rather sensitive change was found in photoconductivity of irradiated graphene under ultra-violet (UV) illumination, suggesting irradiation induced defects affect a photoconductivity properties of the graphene.

Effects of Al thickness in Ti/Al/Ti/Au ohmic contact on AlGaN/GaN heterostructures are studied. Samples having Al thickness of 30, 90 and 120 nm in Ti/Al/Ti/Au have been investigated by electrical and X-ray photoelectron spectroscopy (XPS) depth profile analysis. It is found that thick Al samples show lower resistance and formation of Al-based alloy under the oxidized Al layer.

In this paper, we designed and fabricated large scale micro-light-emitting-diode (LED) arrays and silicon driver for single chip device for realizing as prototypes of heterogeneous optoelectronic integrated circuits (OEICs). The large scale micro-LED arrays were separated by a dry etching method from mesa structure to 16,384 pixels of 128 128, each with a size of 15 µm in radius. Silicon driver was designed the additional bonding pad on each driving transistor for bonding with micro-LED arrays. Fabricated micro-LED arrays and driver were flip-chip bonded using anisotropic conductive adhesive.