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In the course of the last few years, interest in the development of smart cities and progress of smart buildings has increased significantly. This development has been significantly increased due to the development of new technologies, innovative functional materials, electronic components and other products. At the same time, it is imperative to use those products that contribute to the preservation of the environment, and above all to energy saving. Thus, new technologies are becoming increasingly attractive, such as the one based on OLED (Organic Light Emitting Diode) technology, which is used in the production of mobile phones, tablet computers, other devices, as well as light sources. Although this technology has been generally known for more than half a century, commercial application of OLED components was not possible due to insufficient efficiency of products based on it. However, the continuous improvement of characteristics and efficiency enabled their more significant application in the past few years. The aim of this work is to provide adequate information about the possibilities of applying some innovative technologies in the planning and development of smart cities. Especially, becoming more familiar with the basic properties and application possibilities of OLED devices can lead to the life quality improvements of city spaces users.

The mechanisms responsible for the effects of consecutive irradiation and negative bias temperature (NBT) stress in p-channel power vertical double-diffused MOS (VDMOS) transistors are presented in this paper. The investigation was performed in order to clarify the mechanisms responsible for the effects of specific kind of stress in devices previously subjected to the other kind of stress. In addition, it may help in assessing the behaviour of devices subjected to simultaneous irradiation and NBT stressing. It is shown that irradiation of previously NBT stressed devices leads to additional build-up of oxide trapped charge and interface traps, while NBT stress effects in previously irradiated devices depend on gate bias applied during irradiation and on the total dose received. In the cases of low-dose irradiation or irradiation without gate bias, the subsequent NBT stress leads to slight further device degradation. On the other hand, in the cases of devices previously irradiated to high doses or with gate bias applied during irradiation, NBT stress may have a positive role, as it actually anneals a part of radiation-induced degradation. [ABSTRACT FROM AUTHOR]

In this study, which is aimed at assessing a possible relationship between the recoverable and permanent components of negative bias temperature instability (NBTI) degradation, we investigate NBTI in commercial IRF9520 p-channel VDMOSFETs (vertical double diffused MOSFETs) stressed under particular pulsed bias conditions by varying the pulse on-time while keeping the off-time constant and vice versa. The stress-induced threshold voltage shifts are found to be practically independent of duty cycle when the pulse on-time is kept short or the off-time is kept long, and are found to start increasing with duty cycle only when the on-time is increased or the off-time is decreased beyond specific values. These results, which are discussed in terms of dynamic recovery effects and the mechanisms leading to NBTI degradation, point to the existence of an important correlation between the recoverable and permanent components of degradation. [ABSTRACT FROM AUTHOR]

In this study we investigate the dynamic recovery effects in IRF9520 commercial p-channel power vertical double diffused metal–oxide semiconductor field-effect transistors (VDMOSFETs) subjected to negative bias temperature (NBT) stressing under the particular pulsed bias. Particular values of the pulsed stress voltage frequency and duty cycle are chosen in order to analyze the recoverable and permanent components of stress-induced threshold voltage shift in detail. The results are discussed in terms of the mechanisms responsible for buildup of oxide charge and interface traps. The partial recovery during the low level of pulsed gate voltage is ascribed to the removal of recoverable component of degradation, i.e., to passivation/neutralization of shallow oxide traps that are not transformed into the deeper traps (permanent component). Considering the value of characteristic time constant associated with complete removal of the recoverable component of degradation, it is shown that by selecting an appropriate combination of the frequency and duty cycle, the threshold voltage shifts induced under the pulsed negative bias temperature stress conditions can be significantly reduced, which may be utilized for improving the device lifetime in real application circuits. [ABSTRACT FROM AUTHOR]

The effect of annealing on the recovery of electrically stressed power vertical double-diffused metal oxide semiconductor (VDMOS) transistors has been investigated. Behaviors of device threshold voltage and channel carrier mobility have been analyzed in terms of underlying changes in the densities of gate oxide charges and interface traps. The mechanisms responsible for the above-mentioned changes during the recovery of stressed devices have been analyzed as well. The annealing resulted in achieving stable threshold voltage and mobility, but did not ensure full recovery, as part of the stress-induced degradation remained permanent and could not be annealed. Namely, the annealing was found to enhance the neutralization of stress-induced oxide charges and the passivation of stress-induced interface traps, while the stability upon its completion resulted from the significantly decreased density of gate oxide charges and the possible balance between the processes of trap passivation and creation at the SiO2–Si interface. [ABSTRACT FROM AUTHOR]