Hydrogen gas sensors from polysilicon nanobelt devices selectively modified with sensing materials

Nhan Ai Tran, Fu-Ming Pan, Jeng-Tzong Sheu

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Double-junction n+/n-/n+ polysilicon nanobelts featuring selectively deposited sensing materials have been investigated for application as H2 gas sensors. The selective modification of the devices was performed through a combination of localized ablation of a resist and lift-off of a previous catalyst material deposited through e-beam evaporation. Four nanobelt devices, differentiated by their doping concentrations at the n- region (from 2.5 × 1013 to 2.5 × 1014 cm-2), were analyzed in terms of the responses to H2 and their self-heating effects. A low doping concentration improved the response at room temperature, owing to a longer Debye length. The variation in the H2-induced surface potential associated with temperature, accounting for degradation in the response of the nanobelts with Joule heating bias, was analyzed in terms of the I-V characteristics of the double-junction device. Among various catalysts (Pt, Pd, Pt/Pd) evaluated for their H2 sensing characteristics, an ultrathin film of Pt/Pd was most favorable.

Original languageEnglish
Article number505604
Issue number50
StatePublished - 21 Nov 2016


  • double-junction
  • hydrogen sensor
  • localized Joule heating
  • polysilicon nanobelts
  • self-heating


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