초록

Devices including conductometric porous silicon gas sensors, methods of fabricating conductometric porous silicon gas sensors, methods of selecting a device, methods of detecting a concentration of a gas, and methods of analyzing data.

대표청구항 ▼

The invention claimed is: 1. A device, comprising: a conductometric porous silicon gas sensor including a monolithic silicon substrate having a porous silicon layer and a protective layer, wherein the protective layer is disposed on top of the silicon substrate and adjacent to the porous silicon la

The invention claimed is: 1. A device, comprising: a conductometric porous silicon gas sensor including a monolithic silicon substrate having a porous silicon layer and a protective layer, wherein the protective layer is disposed on top of the silicon substrate and adjacent to the porous silicon layer, wherein the protective layer is selected from a silicon carbide layer, a silicon nitride layer, a polymer layer, a silicon oxynitride layer, an insulating dielectric film, a ceramic layer, a photoresist layer, a polyimide layer, and combinations thereof, wherein the porous silicon layer has a first portion and a second portion that are not contiguous, wherein the protective layer has a first portion and a second portion that are not contiguous, wherein the first portion of the protective layer is contiguous with the first portion of the porous silicon layer, wherein the second portion of the protective layer is contiguous with the second portion of the porous silicon layer, wherein a first metal layer is disposed on the first portion of the porous silicon layer and the first portion of the protective layer to form a first contact, wherein a second metal layer is disposed on the second portion of the porous silicon layer and the second portion of the protective layer to form a second contact, and wherein the conductometric porous silicon gas sensor is operative to transduce the presence of a gas into an impedance change across the first contact and the second contact, wherein the impedance change correlates to the gas concentration. 2. The device of claim 1, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration of 1 part per billion and greater. 3. The device of claim 1, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration in at least 2 seconds. 4. The device of claim 1, wherein the impedance change is measured with an impedance analyzer. 5. The device of claim 1, wherein the impedance change is measured with a sensor and shunt circuit. 6. The device of claim 1, wherein the gas concentration is correlated with a change in the magnitude of the impedance or resistance. 7. The device of claim 1, wherein the gas is selected from H2S, HCl, SO2, NH3, and nitric oxide. 8. The device of claim 1, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to at least one of the following: a gas concentration of HCl at 1 part per million and greater, a gas concentration of H2 S at 1 part per million and greater, a gas concentration of SO2 at 1 part per million and greater, a gas concentration of NH3 at 0.4 part per million and greater, a gas concentration of nitric oxide at 1 part per million and greater, and combinations thereof. 9. The device of claim 1, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to at least one of the following: a gas concentration of HCl at 1 part per billion and greater, a gas concentration of H2 S at 1 part per billion and greater, a gas concentration of SO2 at 1 part per billion and greater, a gas concentration of NH3 at 1 part per billion and greater, a gas concentration of nitric oxide at 1 part per billion and greater, and combinations thereof. 10. The device of claim 1, wherein the first metal layer and the second metal layer each comprise a metal selected from titanium, gold, and combinations thereof. 11. The device of claim 1, wherein the conductometric porous silicon gas sensor is operative to transduce the presence of the gas into an impedance change across the first contact and the second contact at room temperature. 12. The device of claim 1, further comprising a coating layer disposed on a third portion of the porous silicon layer that is between the first portion and the second portion of the porous silicon layer. 13. The device of claim 12, wherein the coating layer is selected from tin, gold, and combinations thereof. 14. The device of claim 12, wherein the coating layer is selected from the following: tin oxides, gold clustered oxides, and combinations thereof. 15. The device of claim 12, wherein the coating layer is selected from the following: platinum, oxides thereof, and oxynitrides thereof palladium, oxides thereof, and oxynitrides thereof; iridium, oxides thereof, and oxynitrides thereof rhodium, oxides thereof, and oxynitrides thereof; vanadium, oxides thereof, and oxynitrides thereof ruthenium, oxides thereof, and oxynitrides thereof; titanium, titanium oxide, and titanitum oxynitride; tin oxynitride; and combinations thereof. 16. The device of claim 12, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration at 400 parts per billion and greater. 17. The device of claim 12, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration at 1 part per billion and greater. 18. The device of claim 12, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration of CO at 5 parts per million and greater. 19. The device of claim 12, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration of CO at 1 part per billion and greater. 20. The device of claim 12, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration of NH3 at 1 part per million and greater in the presence of nitric oxide at 20 parts per million and less. 21. The device of claim 1, wherein the porous silicon layer has a hybrid microporous/nanoporous framework, wherein the walls of the microporous framework are superimposed with a nanoporous layer. 22. The device of claim 21, wherein the macroporous framework includes pores approximately 1 to 2 μm wide and 0.5 to 20 μm deep. 23. A device, comprising: a conductometric porous silicon gas sensor including a monolithic silicon substrate having a porous silicon layer and a protective layer; a first contact disposed on a first portion of the porous silicon layer and a first portion of the protective layer; and a second contact disposed on a second portion of the porous silicon layer and a second portion of the protective layer, wherein the conductometric porous silicon gas sensor is operative to transduce the presence of a gas into an impedance change across the first contact and the second contact, wherein the impedance change correlates to the gas concentration. 24. The device of claim 23, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration of 1 part per billion and greater. 25. The device of claim 23, wherein the conductometric porous silicon gas sensor is operative to measure the impedance change corresponding to a gas concentration in at least 2 seconds. 26. The device of claim 23, further comprising a coating layer disposed on a third portion of the porous silicon layer that is between the first portion and the second portion of the porous silicon layer. 27. The device of claim 26, wherein the coating layer is selected from tin, gold, and combinations thereof. 28. The device of claim 26, wherein the coating layer is selected from the following: tin oxides, gold clustered oxides, and combinations thereof. 29. The device of claim 26, wherein the coating layer is selected from the following: platinum, oxides thereof, and oxynitrides thereof; palladium, oxides thereof, and oxynitrides thereof; iridium, oxides thereof, and oxynitrides thereof rhodium, oxides thereof, and oxynitrides thereof vanadium, oxides thereof, and oxynitrides thereof ruthenium, oxides thereof, and oxynitrides thereof; titanium, titanium oxide, and titanitum oxynitride; tin oxynitride; and combinations thereof.