فهرست مطالب m. h. shahrokh abadi

In this paper, the effect of germanium content in Zn1-xGexO as a buffer layer on the performance and efficiency of a solar cell based copper oxide (Cu2O) is investigated. The physical parameters of the solar cell model were selected according to the experimental data and then the new parameters of ZnGeO buffer layer was calculated based on the interpolated parameters of the energy levels of the band structure of binary compounds ZnO and GeO2 to study the solar cell performance for the germanium composition, ranged from 0.35 to 0.75. First, the accuracy of the initial model of the solar cell was verified by comparing its electrical characteristics with experimental data. Then, the characteristics of the initial model were analyzed and characterized in presence of buffer layer. By examining the cell efficiency for the changes of buffer composition (35% to 75% germanium), the minimum efficiency was observed 5.31% at x = 0.35 and the maximum was 7.02% at x = 0.65. The results show that using Zn0.35Ge0.65O buffer, the short circuit current of the cell reaches 11.15 mA with an open circuit voltage up to 1.08 volts.

A biosensor for the detection of E. coli O157: H7 bacterium has been designed by using the mean of an organic field effect transistor, and the behavior of the sensor was studied and analyzed under a simulated environment. The design of biosensor includes two essential parts: scheming the structure and choosing the material. In the structure part, an OCMFET configuration, previously used for DNA hybridization, for the first time has been employed for the detection of E. coli with some modifications. In the modified structure, a microfluidic pathway has been added to let the analyte in and out, which makes it possible to detect low volumes of the bacterium in the stream of analyte efficiently and quickly. For the material part, Pentacene, as an organic semiconductor, has been used due to its valuable parameters such as environmental compatibility, cheapness, and easy manufacturing processes. The simulation results are shown 2 minutes after applying the analyte, containing 100 CFU/mL E. coli, 35 bacteria adhere to the active area of the device, leading to a 72 mV shift in the I-V curve. This shift reaches about 174 mV for 86 contained bacteria within 5 minutes which indicates high sensitivity of the sensor. The fast response time, notable sensitivity, biocompatibility, fabricability with current technology, and affordability are among the other benefits of this structure.