Conformal titanium nitride in a porous silicon matrix: A nanomaterial for in-chip supercapacitors

Kestutis Grigoras, Jari Keskinen, Leif Grönberg, Elina Yli-Rantala, Sampo Laakso, Hannu Välimäki, Pertti Kauranen, Jouni Ahopelto, Mika Prunnila (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

50 Citations (Scopus)

Abstract

Today's supercapacitor energy storages are typically discrete devices aimed for printed boards and power applications. The development of autonomous sensor networks and wearable electronics and the miniaturization of mobile devices would benefit substantially from solutions in which the energy storage is integrated with the active device. Nanostructures based on porous silicon (PS) provide a route towards integration due to the very high inherent surface area to volume ratio and compatibility with microelectronics fabrication processes. Unfortunately, pristine PS has limited wettability and poor chemical stability in electrolytes and the high resistance of the PS matrix severely limits the power efficiency. In this work, we demonstrate that excellent wettability and electro-chemical properties in aqueous and organic electrolytes can be obtained by coating the PS matrix with an ultra-thin layer of titanium nitride by atomic layer deposition. Our approach leads to very high specific capacitance (15 F cm-3), energy density (1.3 mWh cm-3), power density (up to 214 W cm-3) and excellent stability (more than 13,000 cycles). Furthermore, we show that the PS-TiN nanomaterial can be integrated inside a silicon chip monolithically by combining MEMS and nanofabrication techniques. This leads to realization of in-chip supercapacitor, i.e., it opens a new way to exploit the otherwise inactive volume of a silicon chip to store energy.
Original languageEnglish
Pages (from-to)340-345
JournalNano Energy
Volume26
DOIs
Publication statusPublished - 2016
MoE publication typeA1 Journal article-refereed

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Keywords

  • supercapacitor
  • integrated energy storage
  • on-chip integration
  • porous silicon
  • ALD
  • TiN

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