MOS hydrogen sensor with very fast response based on ultra-thin thermal SiO2 film
✍ Scribed by Chi Lu; Zhi Chen
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 702 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0360-3199
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✦ Synopsis
Ultra-thin thermal SiO 2 film
Response time
SiO 2 bulk trap a b s t r a c t An MOS capacitor-type hydrogen gas sensor was fabricated with the structure of Ni/SiO 2 /Si by using conventional silicon wafer technologies. Grown by dry oxidation at 900 C, the thickness of the SiO 2 film was only 24 A ˚. At 150 C, comparing to another MOS capacitor with 148 A ˚-thick oxide and otherwise identical configurations, this sensor showed much faster response speed (the time interval to reach half of the magnitude of the steady-state signal, or t 50% , was only 4 s in response to 1% H 2 without deduction of the delay from the gas delivery system), as well as enhanced signal magnitude (about two times of the former for 1% H 2 ). Based on the hydrogen-binding to the traps in the bulk SiO 2 , a mechanism was proposed to explain the very short response time on the device with the ultra-thin SiO 2 .
The gate leakage in the device is also discussed. The presented sensor demonstrates a promising step in designing low-cost H 2 detectors with very fast responses.