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ZnO thin films were grown on p‐type Si (100) by plasma‐assisted molecular beam epitaxy (PA‐MBE). Before the growth of the ZnO thin films, the initial Zn layers were deposited on the Si substrates. In order to investigate the effects of thermal annealing, the initial Zn layers were annealed at the temperature range from 500 to 700 °C for 30 min under oxygen ambient. The properties of the ZnO thin films with annealed initial Zn layers have been investigated by X‐ray diffraction (XRD), room temperature (RT) photoluminescence (PL), and scanning electron microscopy (SEM).

The GaAs quantum dots in AlGaAs barriers were grown by droplet epitaxy, emitting around 700 nm in wavelength which is compatible with low cost Si based detectors. The excitation power dependent and time resolved micro‐photoluminescence measurements identified optical characteristics of exciton and biexciton states which are attributed to good quantum confinements in GaAs QDs.

GaAs quantum dot (QD) was grown by droplet epitaxy (DE) method and the excitation power dependence of photoluminescence (PL) were carried out. To investigate the effect of annealing temperature on QDs optical properties, the two step RTA process was carried out in a various temperature range from 800 to 1000 °C. As the thermal annealing temperature increases, the PL peak position is blue‐shifted due to the change of the composition and size distribution of QDs, and the highest PL intensity is observed at the sample annealed at 900 °C. The integrated PL intensity (IPL) is plotted against the excitation density in a log‐log scale and the slope was calculated.

We fabricated low‐density GaAs/AlGaAs quantum dots for single photon source by droplet epitaxy. We investigated the emission energies of the dots and underlying superlattice by using photoluminescence and cathodoluminescence measurements. By forming a mesa etched structure, we distinguished the transitions from the superlattice and the dots. And we calculated the diffusion length in this system from the peak shift of the superlattice, and applied the diffusion to the dots to investigate the emission energy shift of the QDs.z

KIMS is a dark matter search experiment using low background CsI(TB) crystals at Yangyang Underground Laboratory in Korea. With a total exposure of 3409 kg⋅d data, we set a new limit on WIMP‐nucleon cross section. We achieved the most stringent limit on the spin‐dependent interaction for a pure proton case. We were able to exclude the DAMA signal region for both spin‐dependent and spin‐independent interaction for the WIMP mass greater than 20 GeV/c2. KIMS experiment is upgraded with 12 CsI(TB) crystals corresponding to a total mass of 104 kg and accumulating data since Jan. 2008.

We demonstrate electron transport in an enhancement mode in‐plane‐gate quantum dot transistor (IPGQDT). Deeply etched trenches allow large positive biases on the IPG with negligible leakage current Strong negative differential resistance (NDR) peaks and single electron tunneling are observed in a wide gate bias window. The position of the NDR peaks systematically moves with the change of the gate bias, suggesting that they originate from resonant tunneling through QD quantum states.

This paper presents a comprehensive model for 1/f noise in poly‐Si thin‐film transistors in the linear regime where the current is controlled by the gate bias with a small fixed drain bias. For small gate biases the conduction and noise generation is dominated by thermionic emission at the grain boundary where as for large gate biases the conduction and noise generation is dominated by drift in the grain bulk region. The generation of the 1/f noise in the grain bulk can explained by the ‘Unified Model’ for crystalline Si‐MOSFET’s. However, the noise from grain boundary should be explained by number fluctuation models such as thermal activation model via barrier height modulation. An expression for the critical barrier height or gate bias, which severs these two regimes, is derived.

We have extensively studied the mechanism of the 137Cs and 134Cs contamination in CsI compounds. The nuclei 137Cs and 134Cs in various samples have been studied using a HPGe detector at deep underground. The main source of the 137Cs contamination in CsI powder was desolved 137Cs in the water used in the chemical process of cesium extraction at company side. We also found that 134Cs was produced mainly from 133Cs by neutron capture. We have successfully produced CsI powder containing no more than 2 mBq/kg of 137Cs by using only ultra‐pure water for whole extraction process from raw ore(pollucite).