Thin ZnO films were directly grown on p-Si(1 0 0) substrates by photoinduced electrodeposition under illumination. In this case, p-Si wafer behaves as a photocathode. At the initial deposition stage, it has been found that the ZnO films grew through three-dimensional instantaneous nucleation followed by diffusion-limited growth mode. In this study, we report that the conductivity type of ZnO films can be changed from n-type to p-type by varying the relative concentration of oxygen in ZnO films through the thermal treatment in air ambient without any doping process. The electrical properties of ZnO/p-Si heterojunctions were investigated via current–voltage (I–V) characteristics. These heterojunctions showed good diode-like, rectifying I–V characteristics and the turn-on voltages of the n-ZnO/p-Si and p-ZnO/p-Si heterojunctions were found to be 0.56 and 0.46 V. From the analysis of temperature dependence of the I–V characteristics, these heterojunctions exhibited that the charge carriers are mainly transported by the activation of the carriers across the barrier height but in a low voltage region under forward bias, transported through the multi-step tunnelling-assisted carrier capture-emission mechanism.

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The elevator is needed healthy and comfortable indoor air quality (IAQ) for using many people, but we found nothing about IAQ studies of an elevator. In general, air in the elevator car is sucked from the elevator's hoistway straight into the car using a fan. The air sucked into the hoistway may be filled with dust, mold and bacteria.This study was performed to measure of characteristics of indoor air quality (PM10, falling bacteria, CO2, Rn and HCHO) in elevator`s hoistway, CAR and lobby of 8 sites (4 apartments and 4 commercial buildings) in Gyeongnam from May, 2010 to January, 2011. With regards to the differences of pollutant distribution among hoistway, CAR, and lobby, the concentration of Rn and HCHO were the highest in hoistway followed by CAR and lobby, and PM10, falling bacteria and CO2 were the highest in CAR followed by hoistway and lobby. Mean concentrations of PM10 were 104.9 μg/m 3 in CAR, 92.3 μg/m 3 in hoistway and 68.2 μg/m 3 in lobby, respectively.

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