Circuital characterisation of space-charge motion with a time-varying applied bias

Chul Kim, Eun Yi Moon, Jungho Hwang, Hiki Hong

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1 Citation (Scopus)


Understanding the behaviour of space-charge between two electrodes is important for a number of applications. The Shockley-Ramo theorem and equivalent circuit models are useful for this; however, fundamental questions of the microscopic nature of the space-charge remain, including the meaning of capacitance and its evolution into a bulk property. Here we show that the microscopic details of the space-charge in terms of resistance and capacitance evolve in a parallel topology to give the macroscopic behaviour via a charge-based circuit or electric-field-based circuit. We describe two approaches to this problem, both of which are based on energy conservation: the energy-to-current transformation rule, and an energy-equivalence-based definition of capacitance. We identify a significant capacitive current due to the rate of change of the capacitance. Further analysis shows that Shockley-Ramo theorem does not apply with a time-varying applied bias, and an additional electric-field-based current is identified to describe the resulting motion of the space-charge. Our results and approach provide a facile platform for a comprehensive understanding of the behaviour of space-charge between electrodes.

Original languageEnglish
Article number11738
JournalScientific reports
Publication statusPublished - 2015 Jul 2

Bibliographical note

Funding Information:
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2013R1A1A2A10058503), Mid-career Researcher Program (#2012-R1A2A2A01005449), National Nuclear R&D Program (#2013-M2B2A9A03051296).

All Science Journal Classification (ASJC) codes

  • General


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