Further investigation of a hydrogen-sensing Pd/GaAs heterostructure field-effect transistor (HFET)

Ching Wen Hung, Tsung Han Tsai, Huey Ing Chen, Yan Ying Tsai, Tzu Pin Chen, Wen Chau Liu

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12 Citations (Scopus)


Based on a GaAs-based heterostructure field-effect transistor (HFET) equipped with a catalytic Pd gate, an interesting Pd/GaAs transistor-type hydrogen sensor is fabricated and studied. A simple model is used to elucidate the on-state and off-state behaviors in the transistor operation. In air and N2 environments, hydrogen-induced effect not only causes an obvious current variation in the saturation region, but also results in a drastic change of sensor response in the cut-off region. The further analyses of electrical characteristics are also presented. The calculated values of IDS operating regime (>0.8 gm,max) are 115.3 (115.1) and 108.2 (106.2) mA/mm in air (N2) and 1% H2/air (1% H2/N2), respectively. The variation trend of gm under the positive gate bias is contrary to that under the negative gate bias in hydrogen-containing ambiance. In addition, the decrease in on-off current ratio (Ion/Ioff) towards hydrogen gas is attributed to the considerable variation of Ioff in the cut-off region.

Original languageEnglish
Pages (from-to)587-592
Number of pages6
JournalSensors and Actuators, B: Chemical
Issue number2
Publication statusPublished - 2008 Jun 16

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry


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