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Characterization of GaN nanostructures by electron field and photo-field emission

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Litovchenko V. , Evtukh A. , Grygoriev A.

tom Vol. 25, No. 3

251--262

The electron field and photo-field emission from GaN nanostructures has been analyzed in this review. In order to explain the obtained experimental results, a model was proposed taking into account the change in carrier concentration distribution in the main and the satellite valley during the emission process. The lowering of work function (due to the increased number of carriers in the satellite valley) can explain the decrease in the Fowler-Nordheim plot slope. It was shown that the energy difference between the main and satellite valley in GaN was decreased in the case of quantum confinement, thus increasing the probability of electron transition from Γ to X valley at same electric fields. Investigations of electron photo-field emission demonstrated that the Fowler-Nordheim plots of the emission current have different slopes for nonilluminated and illuminated devices. A model based on the electron emission from valleys having different specific electron affinities is proposed to explain the experimental results. In the absence of illumination the emission takes place only from the lower valley. Upon UV illumination and presence of a high electric field at the emitter tip, the upper valley of the conduction band appears to be occupied by electrons generated at the valence band.

Doświadczalna weryfikacja parametrów przepływu w kanałach otwartych

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Wędrychowicz W. , Grygoriev A. , Ziółkowski T.

tom Vol. 13, spec. iss. 2/2

232--240

The subject matter of research work contains issues connected with open channel flows (with free fluid surface) and occurrences to be found in them. Free fluid surface flows are often observed in case of water plants, especially in water-power engineering and many others technical applications. Validity of deeper researches concerning occurrences to be appeared in free fluid surface flows come out internalia from fluid mechanics literature studies. There is no many data obtained as results of empirical fluid open flow researches. Most of usable formulas is based on simplified theoretical flow models or experimental experience of scientists. In the research work were taken up into the consideration few basic issues of mentioned flows velocity profiles in open channels, hydraulic jump occurrence etc. There was shown empirical verification results of well-known formulas located in professional literature, which describe mentioned above flow ocurrences based on contemporary measuring possibilities. Obtained results could be helpful for practicians engaged in design processes and usage of open flow installations.