Nanopore FET sensor with non-linear potential profile

1. A nanopore field-effect transistor sensor, comprising

i) a source region and a drain region, defining a source-drain axis;

ii) a channel region between the source region and the drain region; and

iii) a nanopore defined as an opening in the channel region which completely crosses through the channel region, oriented at an angle to the source-drain axis, and having a first orifice and a second orifice, the nanopore being adapted for creating a non-linear potential profile between the first orifice and second orifice in the channel region.

2. The nanopore field-effect transistor sensor according to claim 1 , wherein the first orifice differs from the second orifice thereby creating the non-linear potential profile between the first orifice and second orifice.

3. The nanopore field-effect transistor sensor according to claim 2 , wherein the first orifice and the second orifice differ in area and/or are delimited by edges differing in chemical nature.

4. The nanopore field-effect transistor sensor according to claim 3 , wherein the nanopore tapers from the first orifice towards the second orifice.

5. The nanopore field-effect transistor sensor according to claim 3 , wherein the first orifice and the second orifice are delimited by edges of different permittivity and/or different surface charge.

6. The nanopore field-effect transistor sensor according to claim 5 , wherein the first orifice is delimited by an edge formed of a first gate dielectric layer and the second orifice is delimited by an edge formed of a second gate dielectric layer, the first gate dielectric layer having a chemical composition differing from a chemical composition of the second gate dielectric layer and/or the first gate dielectric layer having a thickness differing from a thickness of the second gate dielectric layer.

7. The nanopore field-effect transistor sensor according to claim 5 , wherein the first orifice and the second orifice are delimited by edges differing in their surface chemical functionalization.

8. The nanopore field-effect transistor sensor according to claim 1 , wherein the channel region comprises:

ia) a first channel region portion comprising the nanopore, and

ib) a second channel region portion not comprising the nanopore; and

wherein

the first channel region portion has a doping concentration which is at least 2 times lower than a doping concentration of the second channel region portion, and/or

the first channel region portion has a bandgap which is at least 5% smaller than a bandgap of the second channel region portion.

9. The nanopore field-effect transistor sensor according to claim 1 , further comprising one or more side gates, the side gates being laterally positioned with respect to the channel region.

10. The nanopore field-effect transistor sensor according to claim 1 , further comprising a layer on the channel region.

11. The nanopore field effect transistor sensor according to claim 10 , wherein the opening defining the nanopore further extends at least partly through the layer.

12. A nanopore field-effect transistor sensor array, comprising at least 50, at least 100 or at least 1000 nanopore field-effect transistor sensors according to claim 1 .

13. The nanopore field-effect transistor sensor according to claim 4 , wherein the first orifice and the second orifice are delimited by edges of different permittivity and/or different surface charge.

14. The nanopore field-effect transistor sensor according to claim 13 , wherein the first orifice is delimited by an edge formed of a first gate dielectric layer and the second orifice is delimited by an edge formed of a second gate dielectric layer, the first gate dielectric layer having a chemical composition differing from a chemical composition of the second gate dielectric layer and/or the first gate dielectric layer having a thickness differing from a thickness of the second gate dielectric layer.

15. A system comprising:

i) the nanopore field-effect transistor sensor according to claim 1 ;

ii) a first electrolyte solution contacting the first orifice of the nanopore; and

iii) a second electrolyte solution contacting the second orifice of the nanopore.

16. The system according to claim 15 , wherein the first electrolyte solution has an ionic strength differing from an ionic strength of the second electrolyte solution.

17. A method for forming a nanopore field-effect transistor sensor, comprising:

a) providing a structure comprising:

i) a substrate;

ii) a source region and a drain region on the substrate, defining a source-drain axis;

iii) a channel region between the source region and the drain region;

iv) optionally a layer on the channel region; and

v) a mask layer over the channel region and the optional layer if present, the mask layer comprising an opening therethrough overlying the channel region, the opening having a first width and being oriented at an angle to the source-drain axis;

b) optionally, shrinking the opening such that the first width is reduced to a second width;

c) etching the optional layer if present, and the channel region, through the opening, thereby forming a nanocavity;

d) optionally, shrinking a width of the nanocavity;

e) optionally, removing the mask layer; and

f) forming a nanopore from the nanocavity by opening the substrate underneath the nanocavity; the nanopore having a first orifice delimited by a first edge and a second orifice delimited by a second edge;

wherein the nanopore is adapted for creating a non-linear potential profile between the first orifice and the second orifice in the channel region by:

performing step c of etching the optional layer if present and the channel region through the opening by anisotropically etching the channel region, and the optional layer if present, in such a way that the first orifice and the second orifice differ in area, and

optionally, modifying the first edge and/or the second edge so that they differ in chemical nature and/or so that they are made of dielectric material differing in thickness.

18. The method according to claim 17 , wherein the first edge and second edge differ in chemical nature by virtue of differing in surface chemical functionalization.

19. A nanopore field-effect transistor sensor, comprising

i) a source region and a drain region, defining a source-drain axis;

ii) a channel region between the source region and the drain region; and

iii) a nanopore defined as an opening in the channel region which completely crosses through the channel region, oriented at an angle to the source-drain axis, having a first orifice and a second orifice, and being adapted for creating a non-linear potential profile between the first and second orifice in the channel region,

wherein the first orifice differs from the second orifice thereby creating the non-linear potential profile between the first orifice and second orifice;

wherein the first orifice and the second orifice differ in area and/or are delimited by edges differing in chemical nature; and

wherein the nanopore tapers from the first orifice towards the second orifice, wherein the first orifice and the second orifice are delimited by edges of different permittivity and/or different surface charge.

20. The nanopore field-effect transistor sensor according to claim 19 , wherein the first orifice is delimited by an edge formed of a first gate dielectric layer and the second orifice is delimited by an edge formed of a second gate dielectric layer, the first gate dielectric layer having a chemical composition differing from a chemical composition of the second gate dielectric layer and/or the first gate dielectric layer having a thickness differing from a thickness of the second gate dielectric layer.