We investigate the effect of light intensity and wavelength of a solar cell device using photoconductive atomic force microscopy(PC-AFM). A POCl3 diffusion doping process is used to produce a p-n junction solar cell device based on a poly- Si wafer, and the electrical properties of prepared solar cells are measured using a solar cell simulator system. The measured open circuit voltage(Voc) is 0.59 V and the short circuit current(Isc) is 48.5 mA. Moreover, the values of the fill factors and efficiencies of the devices are 0.7 and approximately 13.6%, respectively. In addition, PC-AFM, a recent notable method for nano-scale characterization of photovoltaic elements, is used for direct measurements of photoelectric characteristics in limited areas instead of large areas. The effects of changes in the intensity and wavelength of light shining on the element on the photoelectric characteristics are observed. Results obtained through PC-AFM are compared with the electric/optical characteristics data obtained through a solar simulator. The voltage(VPC-AFM) at which the current is 0 A in the I-V characteristic curves increases sharply up to 18 W/m2, peaking and slowly falling as light intensity increases. Here, VPC-AFM at 18 W/m2 is 0.29 V, which corresponds to 59 % of the average Voc value, as measured with the solar simulator. Furthermore, while the light wavelength increases from 300 nm to 1,100 nm, the external quantum efficiency(EQE) and results from PC-AFM show similar trends at the macro scale but reveal different results in several sections, indicating the need for detailed analysis and improvement in the future.

This study suggested comprehensive structural characterization methods for the commercial blue light emitting diodes(LEDs). By using the Z-contrast intensity profile of Cs-corrected high-angle annular dark field scanning transmission electron microscope(HAADF-STEM) images from a commercial lateral GaN-based blue light emitting diode, we obtained important structural information on the epilayer structure of the LED, which would have beendifficult to obtain by conventional analysis. This method was simple but very powerful to obtain structural and chemical information on epi-structures in a nanometer-scale resolution. One of the examples was that we could determine whether the barrier in the multi-quantum well(MQW) was GaN or InGaN. Plan-view TEM observations were performed from the commercial blue LED to characterize the threading dislocations(TDs) and the related V-pit defects. Each TD observed in the region with the total LED epilayer structure including the MQW showed V-pit defects for almost of TDs independent of the TD types: edge-, screw-, mixed TDs. The total TD density from the region with the total LED epilayer structure including the MQW was about 3.6 × 108 cm−2 with a relative ratio of Edge- : Screw- :Mixed-TD portion as 80%: 7%: 13%. However, in the mesa etched region without the MQW total TD density was about 2.5 × 108 cm−2 with a relative ratio of Edge- : Screw- :Mixed TD portion of 86%: 5%: 9 %. The higher TD density in the total LED epilayer structure implied new generation of TDs mostly from the MQW region.

본 연구는 미성숙 혹은 성숙된 3년생 무지개 송어(Oncorhynchus mykiss) 수컷 150마리의 뇌하수체와 정자형성세포의 형태적인 변화를 조사하기 위해서 실시되었다. 3월부터 그 이듬해 2월까지 번식주기에 따라 광학현미경, 투과 및 주사전자현미경으로 정자 형성과 정자완성시기의 미세구조적 변화를 연구하였다. 뇌하수체 호르몬 분비세포의 성숙은 휴지기 (3월부터 8월까지), 정자형성기 (9월부터 11월가지), 번식기 (12월부터 2월까지)의 3가지