| 1. |
- Fare, T., et al.
(författare)
-
Quasi-static and high frequency C(V)-response of thin platinum metal—oxide—silicon structures to ammonia
- 1988
-
Ingår i: Sensors and Actuators. - : Elsevier. - 0250-6874. ; 14:4, s. 369-386
-
Tidskriftsartikel (refereegranskat)abstract
- Quasi-static and high frequency (1 MHz) capacitance—voltage characteristics are reported for thin Pt (⩽6 nm) MOS capacitors for exposures to ammonia in a background atmosphere of 20% O2/Ar. The ammonia-induced voltage shift of the quasi-static capacitance—voltage characteristics is always greater than or equal to the shift of the high-frequency characteristics for a given ammonia concentration. We discuss the differences in the ammonia response for the case of the two different contact metals, Al or Pd. The quasi-static results can be used to show that the decreased sensitivity with Pt film thickness may be only partly related to the high impedance of the Pt film itself. Based on these results, we argue that the intrinsic ammonia sensitivity of Pt films (less than about 20 nm thick) decreases with decreasing film thickness. We also report some results for hydrogen exposure of 1.5 nm Pt films and discuss them together with complementary measurements of the film impedance. It is concluded that ammonia interacts quite differently with the thin Pt film compared to hydrogen. The findings in this paper support a recently proposed model for the ammonia sensitivity of thin catalytic metal films.
|
|
| 2. |
- Lundström, Ingemar, et al.
(författare)
-
Gas sensors based on catalytic metal-gate field-effect devices
- 1986
-
Ingår i: Sensors and Actuators. - : Elsevier. - 0250-6874. ; 10:3-4, s. 399-421
-
Forskningsöversikt (refereegranskat)abstract
- The properties of gas-sensitive semiconductor devices with catalytic metal gates are reviewed, with emphasis on field-effect structures sensitive to hydrogen-containing molecules like H2, NH3, H2S, alcohols, ethylene etc.A brief review of some of the developed device structures are given. The principles of hydrogen sensors with Pd gates are described in some detail. Ammonia-sensitive field-effect devices with thin catalytic metal gates are discussed. Applications of gas-sensitive field-effect devices for studies of catalytic reactions together with electron spectroscopy in UHV systems, for medical diagnosis, in leak detectors and as biosensors are reviewed.
|
|
| 3. |
- Spetz, Anita, et al.
(författare)
-
Optimization of ammonia-sensitive metal-oxide-semiconductor structures with platinum gates
- 1987
-
Ingår i: Sensors and Actuators. - : Elsevier. - 0250-6874. ; 11:4, s. 349-365
-
Tidskriftsartikel (refereegranskat)abstract
- Ammonia gas-sensitive MOS capacitors with platinum as a thin active metal gate have been studied. The influence of parameters such as the thickness and area of the platinum film on the ammonia sensitivity was investigated. Thicknesses of about 10 to 30 nm of platinum were found to be favourable for a large response to small ammonia concentrations. It was further observed that with aluminium as a thick contact material, the response to ammonia was independent of the area of the platinum film. Theoretical and experimental C(V curves were compared to elucidate the mechanism behnd the ammonia sensitivity. it is concluded that the sensitivity arises from the thin catalytic Pt film.
|
|
| 4. |
- Winquist, Fredrik, et al.
(författare)
-
Biosensors based on ammonia sensitive metal-oxide-semiconductor structures
- 1985
-
Ingår i: Sensors and Actuators. - : Elsevier. - 0250-6874. ; 8:2, s. 91-100
-
Tidskriftsartikel (refereegranskat)abstract
- The physical principles behind the ammonia gas sensitivity of thin catalytic metal-oxide-semiconductor structures are briefly described. in particular, it is shown that room temperature operation is possible with good performance. Biosensors based on the combination of these structures with immobilized enzymes are also described. Several substrates of clinical interest, such as urea, creatinine and amino acids are determined by the combination of the structure and corresponding immobilized enzymes. A flow injection analysis system and a 'bioprobe' are described and discussed.
|
|
| 5. |
|
|
| 6. |
|
|
