Chul Min Kim

Optimization of InGaN/GaN multiple quantum well layers by a two-step varied-barrier-growth temperature method

We report the effect of different temperature profiles on the quality of the InGaN/GaN multiple quantum well (MQW) structures by employing photoluminescence (PL) and atomic force microscopy (AFM). We adopted a two-step varied-barrier-growth temperature method to improve the structural and optical properties of the InGaN/GaN MQW layers. The low-temperature GaN barrier layer was introduced to reduce the desorption rate of the indium atoms of the InGaN well, and then the high-temperature GaN barrier was grown to reduce the defects of InGaN/GaN MQWs. When the width of the low-temperature GaN barrier was 50 A and the high-temperature GaN barrier was grown at 1000 °C, the defect and surface roughness were significantly reduced, especially with a reduction in the depth of V-defect as low as 20 A.

1600 Parallel Microchamber Microfluidic Device for Fast Sample Array Preparation Using the Immiscibility of Two Liquids

We present a 1600 parallel microchamber microfluidic device for fast sample array preparation using the immiscibility of two liquids. The trapping efficiency and size of the arrayed sample in the microchambers of a parallel microfluidic device were analyzed at various flow rates. The trapping efficiency of the sample was also inspected according to the position of the microchamber. Samples were successfully arrayed using the device. The trapping efficiency of the sample was 98.69% at 1 mL/h. The trapping efficiency and diameter of the sample decreased as the flow rate increased. Trapping efficiencies also changed according to the position of the microchambers. As the distance of the microchambers from the inlet increased, the sample trapping efficiency decreased. This tendency occurred more clearly at higher flow rates.