Role of interfacial layer thickness on high-κ dielectric-based MOS devices

An attempt has been made to investigate the role of interfacial layer(IL)and its thickness on HfO 2-based high-?metal-oxide-semiconductor(MOS)devices.The capacitance–voltage(C–V)and current–voltage(I–V)characteristics have been simulated using Sentaurus TCAD software for two different IL thicknesses and at different substrate temperatures and doping concentrations.The device performance is found to be improved for an IL thickness of 1nm at higher temperature but deteriorates with further increase in IL thickness.The capacitance value decreases with the increase in IL thickness and a flatband voltage shift(V_(fb))due to the presence of interfacial charges at IL of higher thickness is observed.The analysis of I–V curve further shows that the leakage current change is more prominent at lower temperature for different IL thickness.The temperature dependence C–V curves show that the presence of 1nm IL makes the device more reliable at elevated temperature.

A model to determine soiling,shading and thermal losses from PV yield data

Apart from being a clean source of energy,photovoltaic(PV)power plants are also a source of income generation for its investors and lenders.Therefore,mitigation of system losses is crucial for economic operation of PV plants.Combined losses due to soiling,shading and temperature in PV plants go as high as 50%.Much of these losses are unaccounted initially,which can jeopardize the economic viability of PV projects.This paper aims to provide a model to determine losses due to soiling,shading and temperature using quantities like irradiance,cell temperature,DC power and current,which are readily available in PV yield data captured by the remote monitoring system,without involving any additional sensors or equipment.In this study,soiling,shading and thermal losses were calculated using PV yield data obtained from a 30-kWp PV plant located in Kharagpur,India.The results showed soiling and shading losses as high as 25.7%and 9.7%,respectively,in the month of December.Soiling loss was verified by measuring transmittance loss of coupon glasses installed in the vicinity of the plant.Shading loss was verified by shadow simulation using an architectural tool(SketchUp).Array thermal loss obtained using the proposed methodology was found to be in line with the estimated value obtained from PVsyst simulation.Additionally,using time-series data,the energy losses corresponding to soiling,shading and temperature effects were calculated by a numerical-integration technique.The monetary loss due to these energy losses thus obtained provides criteria for deciding when to mitigate the sources of these losses.