FET gas sensor device

Abstract

A Field Effect Transistor (FET) gas sensor device (100) arranged to sense a gas and a method of sensing a gas by an FET gas sensor device are provided. The FET gas sensor device includes at least one gate (110a, 110b), a source (120), a drain (130), and a semiconductor channel (140). The semiconductor channel and the gate form a FET channel-gate coupling (150) through which the applied gate potential is arranged to control a current flow through the semiconductor channel. The FET gas sensor device further comprises a space (200) arranged between the gate and the semiconductor channel and configured to receive a gas, whereby the received gas is arranged to affect an electrical characteristic of the FET channel-gate coupling, and wherein the gas is coupled between the gate and the semiconductor channel. The FET gas sensor device is arranged to sense gas based on an affected electrical characteristic of the FET channel-gate coupling.

Description

Technical Field

[0001] The present invention relates to a field effect transistor (FET) gas sensor device. Background Art

[0002] Field effect transistors (FETs) can be used, in particular, to determine the gas composition of a gas mixture. For example, the gate electrode of the FET can react to the gas composition, thereby triggering a change in a control voltage applied to the gate electrode. The resulting change in current flow between the source electrode and the drain electrode can be detected and correlated to the concentration of the gas composition.

[0003] This FET sensor can be used to detect atoms, molecules and ions in gases. This sensor for gas analysis is made of (I. S. Shivaraman, C. Svensson and L. Lundkvist, A hydrogen-sensitive MOS field effect transistor, Appl. Phys. Lett. 26, 55 (1975)) was first proposed. In this study, metal oxide semiconductor FET (MOSFET) was used to detect hydrogen.

[0004] However, it should be noted that a common problem with using FETs for gas sensing is that the common architecture or structure of FETs may result in limited sensitivity for sensing gases.

[0005] It is therefore an object of the present invention to provide a FET-type sensor capable of providing increased sensitivity, response time, accuracy and / or specificity associated with gas sensing. Summary of the invention

[0006] It would be of interest to provide alternatives to prior art FET-type gas sensors in order to improve the sensitivity, response time, accuracy and / or specificity of these gas sensors.

[0007] This and other objects are achieved by providing a FET gas sensor device and a method having the features of the independent claims.Preferred embodiments are defined in the dependent claims.

[0008] Therefore, according to a first aspect of the present invention, a field effect transistor FET gas sensor device arranged to sense gas is provided. The FET gas sensor device includes at least one gate, a source, a drain, and a semiconductor channel arranged between the source and the drain. The semiconductor channel and the at least one gate form a FET channel-gate coupling, through which the applied gate potential is arranged to control the current flowing through the semiconductor channel. The FET gas sensor further includes at least one space arranged between the at least one gate and the semiconductor channel. The at least one space is configured to receive gas, whereby the gas received in the at least one space is arranged to affect at least one electrical characteristic of the FET channel-gate coupling, and wherein the FET gas sensor device is arranged to sense gas based on at least one affected electrical characteristic of the FET channel-gate coupling.

[0009] According to a second aspect of the present invention, a method for sensing gas by a field effect transistor FET gas sensor device is provided. The FET gas sensor device includes at least one gate, a source, a drain, and a semiconductor channel arranged between the source and the drain, wherein the semiconductor channel and the at least one gate form a FET channel-gate coupling, and through the FET channel-gate coupling, the gate potential is arranged to control the current through the semiconductor channel. The FET gas sensor further includes at least one space arranged between the at least one gate and the semiconductor channel. The method includes: biasing the source and the drain with a first voltage to generate a current flowing through the semiconductor channel. The method further includes: biasing the gate with a second voltage, and controlling the current flowing through the semiconductor channel via the FET channel-gate coupling formed by the semiconductor and the at least one gate. The method further includes: receiving a gas in at least one space, whereby the gas received in the at least one space is arranged to affect at least one electrical characteristic of the FET channel-gate coupling. The method further includes: sensing the gas based on at least one affected electrical characteristic of the FET channel-gate coupling.

[0010] Therefore, the present invention is based on the concept or idea of ​​providing a FET gas sensor device, which includes one or more gas receiving spaces, which are located between the gate and the semiconductor channel so that the space is directly coupled to the FET channel-gate coupling. By arranging the gas receiving space between the gate and the semiconductor channel, during sensing, the gas to be sensed can be received or injected between the gate and the semiconductor channel. The presence of the gas between the gate and the semiconductor channel in the provided space enhances the ability of the semiconductor channel of the FET gas sensor device to respond to the gas. In other words, the gas received in the space interacts with the FET channel-gate coupling and / or couples to the FET channel-gate coupling. Therefore, the FET gas sensor device improves the sensitivity, response time, accuracy, and / or specificity of gas sensing.

[0011] The present invention is advantageous in that the arrangement of the gate and the semiconductor channel in the same (common) plane (e.g., on the same side (surface) of the substrate) causes the FET gas sensor device to respond effectively to the gas received in the space between the gate and the semiconductor channel. Since the space is directly coupled to the FET channel-gate coupling, the gas sensing capability of the present invention is more efficient than that of the FET sensors of the prior art and in particular the back-gate type FET sensors of the prior art, in which the gate and the semiconductor channel are arranged in different planes (e.g., on opposite sides (surfaces) of the substrate). It has been observed that these types of FET sensors of the prior art have relatively weak capacitive coupling to the semiconductor channel. In sharp contrast, the arrangement of the FET gas sensor device of the present invention achieves strong coupling to the FET channel-gate coupling. The architecture or structure of the FET gas sensor device of the present invention enables direct coupling and / or transduction to the semiconductor channel, which greatly enhances the gas sensitivity of the FET gas sensor device.

[0012] It is a further advantage of the present invention that the structure and / or arrangement of the FET gas sensor device has high transconductance, miniaturization and / or low power consumption.

[0013] A field effect transistor (FET) gas sensor device is provided which is arranged to sense a gas. Here, "gas" refers to basically any gas, in particular hydrogen H 2. The FET gas sensor device includes at least one gate, a source, a drain, and a semiconductor channel arranged between the source and the drain. The potential of the gate is connected to the channel of the semiconductor material, and the voltage bias applied between the source and the drain biases the current to flow between the source and the drain. It will be understood that these FET components and their operation are known to the technician, and any further description thereof is therefore omitted. The semiconductor channel and the at least one gate form a FET channel-gate coupling, through which the applied gate potential is arranged to control the current flowing through the semiconductor channel. Therefore, when the gate is biased with a voltage to change the electric field in the semiconductor channel, the term "FET channel-gate coupling" can be described as representing the correlation between the current through the channel and the gate potential (voltage), thereby forming a FET channel-gate coupling. The FET gas sensor device further includes at least one space arranged between the at least one gate and the semiconductor channel. The term "space" here refers to a three-dimensional (3D) (air) gap, space, chamber, area, void, etc. arranged or disposed between the gate and the semiconductor channel. In other words, since the gate and the semiconductor are physically separated in the FET gas sensor device, a space is provided between the gate and the semiconductor channel.

[0014] At least one space of the FET gas sensor device is configured to receive gas. Therefore, the FET gas sensor device allows gas to enter the space between the gate and the semiconductor channel. The gas received in the at least one space is arranged to affect at least one electrical characteristic of the FET channel-gate coupling. Therefore, in the case where the gas is received (enters) into the space between the gate and the semiconductor channel of the FET gas sensor device, the electrical characteristics of the FET channel-gate coupling may be affected (influence) or acted upon (affected) by the presence of the gas in the space. The FET gas sensor device is arranged to sense the gas based on at least one affected electrical characteristic of the FET channel-gate coupling. Therefore, the FET gas sensor device is arranged or configured to sense or detect (the) gas based on (according to) the electrical characteristics of the FET channel-gate coupling, wherein the gas affects or acts on the electrical characteristics of the FET channel-gate coupling.

[0015] According to an embodiment of the present invention, at least one of the source and drain, at least one gate, a semiconductor channel, and at least one space can be arranged in the same plane. Therefore, the gate, semiconductor channel, space, and source and / or drain of the FET gas sensor device are arranged in the same (common) plane. The arrangement of the FET gas sensor device components in the same common plane causes a particularly effective response of the FET gas sensor device to the gas received in the space between the gate and the semiconductor channel. The architecture or structure of the FET gas sensor device of the present invention enables direct coupling and / or transduction to the semiconductor channel, which greatly enhances the gas sensitivity of the FET gas sensor device. Therefore, the source, drain and channel are arranged in a coplanar configuration. Moreover, at least one gate, at least one air gap, and the channel are arranged in a coplanar configuration. Preferably, at least one of the source or drain, at least one gate, space, and channel are arranged in a coplanar configuration. Preferably, at least one gate, space, channel, source, and gate are arranged in a coplanar configuration. Therefore, at least one gate, space, channel, source, and gate are arranged in a common plane. Preferably, the two gates, the two spaces, the channel, the source, and the gate are arranged in a coplanar configuration. Thus, the two gates, the two spaces, the channel, the source, and the gate are arranged in a common plane.

[0016] According to an embodiment of the present invention, the FET gas sensor device further comprises a substrate, wherein at least one of the source and drain, at least one gate, the semiconductor channel, and at least one space are arranged in a common plane parallel to the surface of the substrate. The arrangement of the FET gas sensor device components in the same common plane parallel to the surface of the substrate allows for very efficient manufacturing of the device, requiring fewer manufacturing steps. This arrangement also provides the possibility of defining the size of the space in the processing of the FET gas sensor device, wherein the size of the space is preferably ≤500nm, which is particularly suitable for gas sensing purposes.

[0017] According to an embodiment of the present invention, the FET gas sensor device may further include at least one layer disposed on at least a portion of the semiconductor channel, wherein the at least one layer includes a first layer arranged to interact with a gas received in at least one space. The term "layer" here refers to a (relatively thin) layer, coating, covering, film, etc. Therefore, the FET gas sensor may include one or more layers, coatings, coverings, and / or films disposed on at least a portion of the semiconductor channel. The advantage of this embodiment is that the layer can improve one or more gas sensing characteristics of the FET gas sensor device.

[0018] The at least one layer may include a first layer, which is arranged to interact with a gas received in at least one space. In other words, the first layer (which may also be represented as a sensing layer) is configured or arranged to interact with a gas received in a space. The first (sensing) layer is thus docked with a gas received in at least one space between a gate and a semiconductor channel. The gas received in the space may interact with the first layer, and the gas may thereby affect at least one electrical characteristic of the FET channel-gate coupling. In other words, the interaction between the first layer and the gas is coupled to the FET channel-gate coupling, and thereby modulates the potential (voltage) emitted from the gate and sensed by the semiconductor channel. The gas received or injected into the space interacts with the first layer and is able to change the electrical characteristics of the FET channel-gate coupling. Therefore, the FET gas sensor device is arranged to sense gas based on the affected electrical characteristics of the FET channel-gate coupling, whereby this effect is enhanced by the first layer. According to an example, the first layer may be configured for enhanced interaction with one or more target compounds (relative to other components of the gas) in the gas. It should be noted that the differentiated interaction of the first layer with various specific target compounds may allow for even more specific sensing or detection of the target compounds.

[0019] According to an embodiment of the present invention, the at least one layer includes a portion arranged on the surface of the semiconductor channel facing the gate. Arranging the first layer on the surface of the channel facing the gate can increase the coupling between the gate, the sensing layer and the semiconductor channel, thereby giving increased sensitivity. In one embodiment, the side surface of the semiconductor channel faces the gate, and the first layer is arranged on the side surface. Therefore, the first layer is arranged between the gate / space and the semiconductor channel, thereby allowing direct coupling.

[0020] According to an example of the present invention, the at least one layer includes a first portion disposed on a surface of the channel facing one gate, and a second portion disposed on a surface of the channel facing a second gate. According to an example, the first layer includes a portion disposed on a surface of the channel coplanar with the gate, the space, the channel, the source, and the drain.

[0021] According to an embodiment of the present invention, the first layer may include at least one metal. Thus, the first layer may include one or more metals, or even consist of one or more metals. This embodiment is advantageous in that the metallic first layer may even further enhance the gas sensitivity of the FET gas sensor device.

[0022] According to an embodiment of the present invention, the first layer includes one of the following: a film of at least one metal; metal nanoparticles (NP); and nanoparticles of at least one metal selected from the group consisting of platinum Pt, palladium Pd, gold Au, and nickel Ni. Therefore, the first layer may include or constitute a (relatively thin) film of one or more metals, or the first layer may include nanoparticles of metals of platinum Pt, palladium Pd, gold Au, and / or nickel Ni. "Nanoparticles" refer to particles with a small size of approximately less than 100nm and preferably less than 20nm. The advantage of this embodiment is that the metal film or nanoparticles of the first layer are particularly suitable for the gas sensitivity of the FET gas sensor device. The nanoparticles can be designed to have a desired size, which allows enhanced interaction with specific gas species. The particular advantage of this embodiment is that the nanoparticles of the metal mentioned act as molecular hydrogen H 2 The catalyst is used to generate a reaction and penetrate the first layer toward the interface between the sensing layer and the semiconductor channel. The nanoparticles may include alloy or oxide nanoparticles.

[0023] According to an embodiment of the present invention, the at least one layer may include a second layer arranged on at least a portion of the first layer, wherein the second layer includes at least one polymer and is arranged to protect the first layer from moisture. Thus, the FET gas sensor may include a second layer, the second layer including or consisting of one or more polymers, and wherein the second layer is at least partially arranged on the first layer so as to protect the first layer from moisture.

[0024] According to an embodiment of the present invention, the at least one layer may include a third layer, wherein the third layer is a dielectric and is arranged to passivate the surface of the semiconductor channel. Therefore, the FET gas sensor may include a third dielectric layer, which is configured or arranged to passivate the surface of the semiconductor channel. The term "passivation" here refers to protection, protection, etc. The third layer (which may also be denoted as a barrier layer) may be configured to protect the semiconductor channel from degradation by the gas. According to an example, the third (barrier) layer may include or even constitute an oxide. According to an example, the third layer may include an oxide (e.g. silicon dioxide SiO 2 、HfO x 、Aluminum oxide AlO x ) and at least one of a nitride. The third layer may be, for example, an electrical insulator.

[0025] According to an embodiment of the present invention, the third layer may be arranged on at least a portion of the semiconductor channel, and the first layer may be arranged on at least a portion of the third layer. Thus, the third (blocking) layer is arranged on the semiconductor channel, and the first (sensing) layer is arranged on the third (blocking) layer. According to an example, the third layer may include the first layer.

[0026] According to an embodiment of the present invention, the third layer may have a thickness in the range of 0.5 nm to 10 nm. Therefore, the third layer may be relatively thin. Having a space or distance of, for example, less than 500 nm between the gate and the semiconductor channel may ensure that a main conduction channel is generated in the side surface of the semiconductor channel or nanowire, which is separated from the first layer only by the third layer. The relatively thin third layer according to this embodiment may allow electrons to tunnel through the third layer. In an example, electrons may tunnel between the first layer (metal NPs embedded in the first layer) and the semiconductor channel, thereby balancing them. Therefore, NPs with potential energy below the Fermi level will be filled with electrons. When exposed to H 2 When the gas is present, for example, Pd NP (palladium nanoparticles) can react with H 2 The gas reaction will form a new phase in the NP and form a new phase between the NP and SiO 2 The interface dipoles are generated between the Pd NPs, which will increase the potential energy of the NPs. Therefore, some of the filled NP states will be lifted above the Fermi level, and the electrons in these states will be detrapped back to the semiconductor channel to generate a current signal. The electron trapping / detrapping process is very common in Pd NP-H 2 Direct communication between the reaction and the main conduction channel is created, resulting in very efficient signal transduction.

[0027] According to an embodiment of the invention, the third layer may have a thickness in the range of 0.5 nm to 5 nm.This embodiment is particularly advantageous with regard to the tunneling effect as described before, since the (very) thin third layer leads to an even more efficient signal transduction.

[0028] According to an embodiment of the present invention, the semiconductor channel may extend along an axis A, and wherein the FET gas sensor device comprises two gates, which are arranged on opposite sides of the semiconductor channel perpendicular to the axis A. The advantage of this embodiment is that providing two gates can enhance the FET channel-gate coupling, thereby causing a higher sensitivity to the gas received in and / or present in the space between the gate and the semiconductor channel. Therefore, according to this embodiment, the FET gas sensor device is therefore provided with a double-sided gate architecture, which can even further enhance its gas sensitivity compared to a single-sided gate architecture including a single gate. According to one embodiment of the present invention, the two gates, the source, the drain, the channel, and the space are arranged in a common plane, which is on the surface of the substrate and parallel to the surface of the substrate.

[0029] According to an embodiment of the present invention, at least a portion of the semiconductor channel may include a nanowire. The term "nanowire" here refers to a semiconductor channel in the form of a thin wire, the cross-sectional diameter of which is preferably less than 100nm. The advantage of this embodiment is that a nanowire with a relatively small cross-section (i.e., a relatively small cross-sectional area of ​​the semiconductor channel) can increase the coupling between the semiconductor channel and the first layer (if provided). In the case of providing a first layer, according to an example, at least a portion of the first layer can be set on the nanowire. In addition, the semiconductor channel can be a 1D nanowire (channel), wherein the 1D nanowire has a particularly strong electrical coupling with the first layer.

[0030] According to an embodiment of the present invention, the FET gas sensor device may further include a substrate, wherein at least one of the at least one gate, source, drain, and semiconductor channel is arranged on the surface of the substrate. Therefore, the gate, source, drain, and / or semiconductor channel are arranged on the same surface (i.e., the same side) of the substrate. The term substrate here refers to a substrate for mechanically and / or electrically supporting the components arranged thereon. The substrate may be insulating.

[0031] According to an embodiment of the present invention, the semiconductor channel may be arranged above the surface of the substrate. Thus, the semiconductor channel may be suspended, and this arrangement may be represented as a "floating (semiconductor) channel". The advantage of this embodiment is that the FET gas sensor device achieves even further improved thermal management. For example, in the case of providing an insulating substrate, the heat dissipation from the semiconductor channel (e.g., in the form of a (1D) nanowire) to the insulating substrate is significantly reduced. As a result, heat from the Joule effect of the semiconductor channel current accumulates in the semiconductor channel, and the semiconductor channel (and the first layer (if provided)) is heated. This increased temperature can accelerate the reaction of the FET gas sensor device and thereby improve the sensing sensitivity and / or response time of the FET gas sensor device.

[0032] According to an embodiment of the present invention, the FET gas sensor device may further include a measuring unit configured to measure at least one electrical characteristic affected by the FET channel-gate coupling, and sense the gas based on the measured at least one electrical characteristic affected by the FET channel-gate coupling. "Measuring unit" here refers to any unit, device, arrangement, component, etc. arranged or configured to measure the electrical characteristic affected by the FET channel-gate coupling. The advantage of this embodiment is that the measuring unit can efficiently and accurately measure the electrical characteristic affected by the FET channel-gate coupling. Therefore, the FET gas sensor device can sense and / or detect gas even more efficiently and accurately.

[0033] According to an embodiment of the present invention, the measuring unit may be further configured to determine the molecular hydrogen H in the gas based on at least one electrical characteristic affected by the FET channel-gate coupling. 2 The present embodiment senses and / or detects molecular hydrogen H in a FET gas sensor device. 2 The ability is beneficial.

[0034] According to an embodiment of the present invention, the source, drain and semiconductor channel may be formed from the same semiconductor material layer. Thus, the source, drain and semiconductor channel (structure) of the FET gas sensor device are formed from the same (common) semiconductor material layer. Forming the source, drain and channel by patterning the source, drain and channel from a thin film of the same material layer may allow very efficient manufacturing of the device. Forming these FET gas sensor device components from the same semiconductor material may be performed, for example, via photolithographic patterning followed by dry etching.

[0035] According to an embodiment of the invention, at least one space is ≤ 500 nm.Therefore, the space arranged between at least one gate and the semiconductor channel of the FET gas sensor device is smaller than or equal to 500 nm.

[0036] According to an example of the present invention, the FET gas sensor device is configured to passively or actively induce a gas flow through at least one space of the FET gas sensor device. The FET gas sensor device may include any unit, device, etc. for driving the gas flow to the gas receiving space and through the gas receiving space. Such passive or active gas flow induction can even further improve the sensing sensitivity and / or response time of the FET gas sensor device.

[0037] According to an embodiment of the second aspect of the invention, the method may further comprise: measuring at least one affected electrical characteristic of the FET channel-gate coupling; and sensing the gas based on the measured at least one affected electrical characteristic of the FET channel-gate coupling.

[0038] According to an embodiment of the second aspect of the present invention, the method may further include providing a layer on at least a portion of the semiconductor channel, wherein the layer includes one of the following: a film of at least one metal; metal nanoparticles; and nanoparticles of at least one metal selected from the group consisting of platinum Pt, palladium Pd, gold Au, and nickel Ni. The method may further include: measuring a current through the semiconductor channel, and determining molecular hydrogen H in the gas based on the measured current. 2 concentration.

[0039] Further objectives, features and advantages of the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims.Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] This and other aspects of the invention will now be described in more detail, with reference to the appended drawings showing one or more embodiments of the invention.

[0041] Figure 1 A FET gas sensor 10 according to an example of the prior art is schematically shown.

[0042] Figure 2a A FET gas sensor device according to an exemplary embodiment of the invention is schematically shown.

[0043] Figure 2b to Figure 2e A cross section of a FET gas sensor device according to an exemplary embodiment of the present invention is schematically shown.

[0044] Figure 3a A FET gas sensor device according to an exemplary embodiment of the invention is schematically shown.

[0045] Figure 3b A cross section of a FET gas sensor device according to an exemplary embodiment of the present invention is schematically shown.

[0046] Figure 4a A FET gas sensor device according to an exemplary embodiment of the invention is schematically shown.

[0047] Figure 4b A cross section of a FET gas sensor device according to an exemplary embodiment of the present invention is schematically shown.

[0048] Figure 5a A FET gas sensor device according to an exemplary embodiment of the invention is schematically shown.

[0049] Figure 5b A cross section of a FET gas sensor device according to an exemplary embodiment of the present invention is schematically shown.

[0050] Figure 6 A flow chart of a method according to an exemplary embodiment of the present invention is schematically shown.

[0051] Figure 7a and Figure 7b The performance of a FET gas sensor device according to an exemplary embodiment of the present invention is schematically illustrated. DETAILED DESCRIPTION

[0052] Figure 1 A FET gas sensor 10 according to an example of the prior art is schematically shown. Gas sensing is very important for safety and environmental monitoring. Hydrogen sensing is taken as an example, but other gases can also be sensed. Hydrogen is emphasized as a clean fuel because only water is produced in hydrogen combustion. At the same time, hydrogen is a flammable gas with a low explosion limit of 4% by volume in air. Therefore, even relatively low levels of hydrogen leakage may be a serious concern for its safe production and use. As a result, there is a high demand for sensitive and fast sensors for gas (hydrogen) leak detection, and especially for safety needs in hydrogen energy development.

[0053] FETs have been explored as a device platform for hydrogen sensing due to their high transconductance, miniaturization, and low energy consumption. Figure 1 The prior art FET gas sensor 10 illustrated in FIG. 1 includes a source 120, a drain 130, and a semiconductor channel 140 arranged between the source 120 and the drain 130. The source 120, the drain 130, and the semiconductor channel 140 are arranged on an insulating substrate 145. The insulating substrate 145 is in turn arranged on the gate 110. However, a problem with such a FET gas sensor 10 is the low (limited) gas sensitivity and / or detection limit. Therefore, it is of interest to provide an alternative to the prior art FET-type gas sensors in order to improve the sensitivity, response time, accuracy, and / or specificity of these gas sensors.

[0054] Figure 2a Schematically shows a FET gas sensor device 100 according to an exemplary embodiment of the present invention. Figure 1 The side gate FET gas sensor device may be represented in FIG. 1 and is arranged to sense a gas, such as hydrogen H 2 The FET gas sensor device 100 includes at least one gate 110a. Figure 2a , only a single gate 110a is shown, but the FET gas sensor device 100 may alternatively include two or more gates. The FET gas sensor device 100 further includes a source 120, a drain 130, and a semiconductor channel 140 arranged between the source 120 and the drain 130. The semiconductor channel 140 extends along the axis A, and when the source 120 and the drain 130 are arranged at both ends of the semiconductor channel 140, the source 120, the drain 130, and the semiconductor channel 140 form an array of components extending along the axis A.

[0055] According to this example of the FET gas sensor device 100, the gate 110a, the source 120, the drain 130 and the semiconductor channel 140 are arranged on an insulating substrate 145. The gate 110a, the source 120, the drain 130 and the semiconductor channel 140 are thereby arranged in a common plane. The semiconductor channel 140 and the gate 110a form a (schematically indicated) FET channel-gate coupling 150, by which the potential applied to the gate 110a is arranged to control the current flowing through the semiconductor channel 140. The FET channel-gate coupling 150 thereby represents the correlation between the current through the semiconductor channel 140 and the potential (voltage) of the gate 110a, thereby forming the FET channel-gate coupling 150.

[0056] The gate 110a is physically separated from the semiconductor channel 140 in a direction B perpendicular to the axis A. The FET gas sensor device 100 thus includes at least one space 200 indicated by a dotted line and arranged between the gate 110a and the semiconductor channel 140. The space 200 here constitutes a three-dimensional (3D) space, a chamber, an area, a gap, etc. arranged or disposed between the gate 110a and the semiconductor channel 140. Therefore, the gate 110a is spaced apart from the semiconductor channel 140, thereby forming a gap between the gate 110a and the semiconductor channel 140, whereby the gap is not occupied by solid material. The gap forms a gas receiving space 200 for receiving the gas to be sensed. The space 200 can be open to the environment to allow the gas to communicate with the environment. Therefore, the gas present in the gas receiving space 200 can be replaced by a new gas from the environment.

[0057] The width w of the space 200 may be defined by the arrangement of the gate 110a from the semiconductor channel 140 (i.e., the distance between the gate 110a and the semiconductor channel 140 parallel to the direction B). The length l of the space 200 may be defined by the length of the gate 110a and / or the semiconductor channel 140 parallel to the axis A. The height h of the space 200 may be defined by the height of the gate 110a and / or the semiconductor channel 140 perpendicular to the axis A and perpendicular to the direction B. Figure 1 In the example of the FET gas sensor device 100 , the space 200 provided between the gate 110 a and the semiconductor channel 140 has a parallelepiped shape as indicated by a dotted line.

[0058] The space 200 is configured to receive a gas because the FET gas sensor device 100 allows gas to enter the space 200 between the gate 110a and the semiconductor channel 140. The gas received in the space 200 is arranged to affect at least one electrical characteristic of the FET channel-gate coupling 150. The FET gas sensor device 100 is arranged to sense the gas based on the affected at least one electrical characteristic of the FET channel-gate coupling 150. Therefore, the FET gas sensor device 100 is arranged or configured to sense or detect the gas based on (according to) the electrical characteristic of the FET channel-gate coupling 150, wherein the gas affects or acts on the electrical characteristic of the FET channel-gate coupling 150.

[0059] Figure 2b Schematically shows a cross section of a FET gas sensor device 100 along an axis A according to an exemplary embodiment of the present invention. Figure 2b The FET gas sensor device 100 illustrated in FIG. Figure 2a The FET gas sensor device 100 illustrated in FIG. Figure 2a and associated text to increase understanding of the features and / or functionality of the FET gas sensor device 100. Figure 2b , a semiconductor channel 140 and a gate 110a (the semiconductor channel and the gate are arranged on an insulating substrate 145) are arranged at a certain distance from each other along a direction B perpendicular to the axis A. The gate 110a and the semiconductor channel 140 thereby form a space 200 between the gate 110a and the semiconductor channel 140. The distance between the semiconductor channel 140 and the gate 110a defines a width w of the space 200, and a height h of the space 200 is defined by the height of the semiconductor channel 140 and / or the gate 110a. The space 200 is configured to receive a gas, whereby the gas received in the space 200 is arranged to affect the electrical characteristics of the FET channel-gate coupling 150. The FET gas sensor device 100 is arranged to sense the gas based on the affected electrical characteristics of the FET channel-gate coupling 150.

[0060] like Figure 2bThe FET gas sensor device 100 illustrated in the figure includes a first layer (sensing layer) 300, which is disposed on at least a portion of the semiconductor channel 140. The first layer 300 (also indicated as the sensing layer) is arranged to interact with the gas received in the space 200. The first layer 300 (which may include at least one metal) may further include or be composed of a film of a metal, or include nanoparticles of a metal selected from the group consisting of platinum Pt, palladium Pd, gold Au, and nickel Ni. One or more electrical properties of the FET channel-gate coupling 150 (e.g., the conductance of the semiconductor channel 140) are modulated with the gate 110a, and the first layer 300 is directly coupled to the semiconductor channel 140. The FET channel-gate coupling 150 is enhanced by the first layer 300 being located between the semiconductor channel 140 and the gate 110a. According to one example, the presence of gas in the gas receiving space 200 may affect the surface charge density of the first layer 300 and may affect the conduction characteristics of the semiconductor channel 140. According to Figure 2b According to an example, at least a portion of the first layer 300 is arranged between the gate 110a and the semiconductor channel 140. One interaction mechanism may involve adsorption or adsorption of a compound on or in the first layer 300 and changing the charge distribution in the layer on the semiconductor channel 140. The change in charge distribution may be converted into a potential signal seen by the semiconductor channel 140. According to an example, the first layer 300 may be provided as a lining layer configured to at least partially enclose the space 200. According to an example, at least a portion of the layer 300 is provided on a side surface of the channel. According to an example, at least a portion of the layer 300 is provided on a surface of the channel facing the space and the gate. According to another example, the first layer 300 is provided so that it is in gas communication with a gas present in the gas receiving space 200. The minimum distance between the surface of the first layer 300 and the surface of the gate 110a is equal to or less than 500nm. Figure 2b In the example of FIG. 5 , the distance is 5 nm to 100 nm, as this size is particularly suitable for gas sensing purposes.

[0061] Figure 2c Schematically shows a cross section of a FET gas sensor device 100 according to an exemplary embodiment of the present invention. Figure 2c The FET gas sensor device 100 illustrated in FIG. Figure 2b The FET gas sensor device 100 illustrated in FIG. Figure 2b and associated text to increase understanding of the features and / or functionality of the FET gas sensor device 100. Figure 2b Compared to the FET gas sensor device 100 shown, Figure 2cThe illustrated FET gas sensor device 100 further includes a second layer 310 arranged on at least a portion of the first layer 300. Thus, the first layer 300 is disposed on at least a portion of the semiconductor channel 140, and the second layer 310 is arranged on at least a portion of the first layer 300. The second layer 310 includes at least one polymer and is arranged to protect the first layer 300 from moisture.

[0062] Figure 2d Schematically shows a cross section of a FET gas sensor device 100 according to an exemplary embodiment of the present invention. Figure 2b Compared to the FET gas sensor device 100 shown, Figure 2d The illustrated FET gas sensor device 100 further includes a third layer 320 disposed on at least a portion of the semiconductor channel 140. The third layer 320 (also indicated as a barrier layer or a passivation layer) of the FET gas sensor device 100 is a dielectric and is arranged to passivate the surface of the semiconductor channel 140. The third layer 320 is disposed on at least a portion of the semiconductor channel 140, and the first layer 300 is disposed on at least a portion of the third layer 320. According to one example, gas molecules in the space 200 may form a dipole layer at the interface between the first layer 300 and the third layer 320, and may affect the conductive properties of the semiconductor channel 140. According to yet another example, the gas introduced into the space 200 may interact with traps at the interface between the third (dielectric) layer 320 and the semiconductor channel 140, and may affect the electrical properties of the FET channel-gate coupling 150.

[0063] Figure 2e The cross section of a FET gas sensor device 100 according to an exemplary embodiment of the present invention is schematically shown. The FET gas sensor device 100 includes a semiconductor channel 140 according to Figure 2b and the first layer 300 of the associated text, according to Figure 2c and the second layer 310 of associated text, and according to Figure 2d and a third layer 320 of associated text.

[0064] Figure 3a A FET gas sensor device 100 according to an exemplary embodiment of the present invention is schematically shown. Figure 3a The FET gas sensor device 100 illustrated in FIG. Figure 2a The FET gas sensor device 100 illustrated in FIG. Figure 2a and associated text to increase understanding of the features and / or functionality of the FET gas sensor device 100. Figure 3a In the embodiment of the present invention, at least a portion of the semiconductor channel 140 includes nanowires. Figure 3aAs shown, the (entire) semiconductor channel 140 constitutes a nanowire, and the nanowire may, for example, comprise silicon Si. The width of the nanowire parallel to the direction B is as follows: Figure 2a The width of the semiconductor channel 140 is shown to be smaller in comparison. Here, at least one space 200 arranged or configured to receive a gas is arranged between the at least one gate 110a and the semiconductor channel 140 including the nanowires.

[0065] Figure 3b Schematically shows a cross section of a FET gas sensor device according to an exemplary embodiment of the present invention. Figure 3b The FET gas sensor device 100 illustrated in FIG. Figure 3a The FET gas sensor device 100 illustrated in FIG. Figure 3a and associated text to increase understanding of the features and / or functions of the FET gas sensor device 100. The first layer 300 is disposed on at least a portion of the nanowire (semiconductor channel) 140. The first layer 300 includes nanoparticles of a metal, as schematically indicated by dots, wherein the metal is selected from the group consisting of platinum Pt, palladium Pd, gold Au, and nickel Ni.

[0066] The FET gas sensor device 100 further comprises a third (barrier) layer 320, wherein the third layer 320 may comprise an oxide. Having a space or distance of less than 500 nm between the gate and the channel may ensure that a main conduction channel is created in the side surface of the channel or nanowire, which is separated from the metal nanoparticles embedded in the first layer only by the third layer. In an example, the oxide of the third layer is SiO with a thickness of less than 10 nm. 2 In the example, the third oxide layer is SiO with a thickness of less than 7 nm. 2 In the example, the third oxide layer is SiO with a thickness of less than 5 nm. 2 In the example, the third oxide layer is SiO with a thickness of less than 2 nm. 2 In the example, the third oxide layer is SiO with a thickness greater than 0.5 nm. 2 In the example, the third oxide layer is SiO with a thickness greater than 1 nm. 2 Having a thin third layer can allow electrons to tunnel through the third layer. In the example, electrons can tunnel between the metal nanoparticles embedded in the first layer and the semiconductor channel, thereby equilibrating them. Therefore, NPs with potential energy below the Fermi level will be filled with electrons. When exposed to H 2 When the gas is present, Pd NPs can react with H 2 The gas reaction will form a new phase in the NP and form a new phase between the NP and SiO 2The interfacial dipoles are generated between the PdNPs, which will increase the potential energy of the NPs. Therefore, some of the filled NP states will be lifted above the Fermi level, and the electrons in these states will be detrapped back to the semiconductor channel, generating a current signal. 2 Direct communication between the reaction and the main conduction channel is created, resulting in very efficient signal transduction.

[0067] Figure 4a The FET gas sensor device 100 according to an exemplary embodiment of the present invention is schematically shown. The semiconductor channel 140 is Figure 3a An example of a FET gas sensor device 100 is illustrated as a (silicon Si) nanowire. The FET gas sensor device 100 includes two gates 110a, 110b arranged on opposite sides of a semiconductor channel 140 perpendicular to the axis A. Therefore, each of the gates 110a, 110b is separated from the semiconductor channel 140 along a direction B perpendicular to the axis A. Therefore, the (single) side gate FET gas sensor device 100 disclosed in the present invention is not limited to the embodiment of the present invention. Figure 2a to Figure 2e , Figure 3a and / or Figure 3b The FET gas sensor device 100 is compared to Figure 4a The FET gas sensor device 100 in represents a double-side gate FET gas sensor device 100. Here, two spaces 200 arranged or configured to receive gas are arranged on both sides of the semiconductor channel 140 between the two gates 110a, 110b and the semiconductor channel 140.

[0068] Figure 4b Schematically shows a cross section of a FET gas sensor device 100 according to an exemplary embodiment of the present invention. Figure 4b The FET gas sensor device 100 illustrated in FIG. Figure 4a The FET gas sensor device 100 illustrated in FIG. Figure 4a and associated text to increase understanding of the features and / or functions of the FET gas sensor device 100. The first layer 300 is disposed on at least a portion of the nanowire (semiconductor channel) 140. The first layer 300 includes nanoparticles of a metal, as schematically indicated by dots, wherein the metal is selected from the group consisting of platinum Pt, palladium Pd, gold Au, and nickel Ni. The FET gas sensor device 100 further includes a third (barrier) layer 320, wherein the third layer 320 may include an oxide.

[0069] Figure 5a A FET gas sensor device 100 according to an exemplary embodiment of the present invention is schematically shown. Figure 5aThe FET gas sensor device 100 illustrated in FIG. Figure 4a The FET gas sensor device 100 illustrated in FIG. Figure 4a and associated text to increase understanding of the features and / or functionality of the FET gas sensor device 100. Figure 4a In contrast, the semiconductor channel 140 (in the form of a nanowire) is arranged above the surface of the substrate 145. Therefore, the semiconductor channel 140 is suspended by the source 120 and the drain 130.

[0070] Figure 5b A cross section of a FET gas sensor device 100 according to an exemplary embodiment of the present invention is schematically illustrated, showing a suspended arrangement of a semiconductor channel 140 above the surface of a substrate 145 .

[0071] Figure 6 A flow chart of a method 500 for sensing a gas by a FET gas sensor device is shown. The FET gas sensor device includes at least one gate, a source, a drain, and a semiconductor channel arranged between the source and the drain, wherein the semiconductor channel and the at least one gate form a FET channel-gate coupling, through which the gate potential is arranged to control a current through the semiconductor channel. The FET gas sensor further includes at least one space arranged between the at least one gate and the semiconductor channel. The method 500 includes the steps of biasing 510 the source and the drain with a first voltage to generate a current flowing through the semiconductor channel. The method further includes the steps of biasing 520 the gate with a second voltage and controlling the current flowing through the semiconductor channel via the FET channel-gate coupling formed by the semiconductor and the at least one gate. The method further includes the steps of receiving 530 a gas in at least one space, whereby the gas received in the at least one space is arranged to affect at least one electrical characteristic of the FET channel-gate coupling. The method further includes the steps of sensing 540 a gas based on the affected at least one electrical characteristic of the FET channel-gate coupling.

[0072] Figure 7a Schematically shows a method for Figure 2a , Figure 2b , Figure 3a and / or Figure 3b The performance of the (single) side gate FET gas sensor device 100 according to an exemplary embodiment of the present invention. Figure 7a In the figure, a prior art FET sensor (such as Figure 1 a. Figure 1 b) and the voltage signal (ΔV TComparison of the change of (V)) with time (s). Both the prior art FET sensor and the FET gas sensor device 100 are subjected to a conventional air flow. At the position of the first arrow 700, molecular hydrogen H is introduced at a concentration of 2000 ppm. 2 . The voltage signal 710 of the prior art FET sensor shows almost no response, while the voltage signal 720 of the FET sensor device 100 according to the present invention shows a significant response. At the position of the second arrow 730, air is introduced and the curve shows recovery behavior. This process is cycled several times with a repeatable response, showing a significant response of the FET gas sensor device 100 of the present invention to the gas, while the prior art FET sensor shows minimal response to the gas.

[0073] Figure 7b Schematically shows a method for Figure 4a , Figure 4b , Figure 5a and / or Figure 5b Compared with the FET gas sensor device 100 according to the exemplary embodiment of the present invention, the double-side gate FET gas sensor device 100 has, for example, Figure 2a , Figure 2b , Figure 3a and / or Figure 3b The performance of the FET gas sensor device 100 according to the exemplary embodiment of the present invention is shown in FIG. 1 . At the position of the first arrow 740, molecular hydrogen H having a concentration of 2000 ppm is introduced. 2 The voltage signal 750 of the dual-side gate FET gas sensor device 100 shows a more significant response than the voltage signal 760 of the single-side gate FET gas sensor device 100. At the location of the second arrow 770, air is introduced and the curve shows recovery behavior. This process is cycled several times with a repeatable response.

[0074] Those skilled in the art recognize that the present invention is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, one or more of the gates 110a, 110b, the semiconductor channel 140, the space 200, etc. may have shapes, dimensions, and / or sizes different from those depicted / described.

Claims

1. A field effect transistor (FET) gas sensor device (100) arranged to sense a gas, comprising: at least one gate (110a, 110b), Source (120), a drain (130), a semiconductor channel (140) arranged between the source and the drain, wherein the semiconductor channel and the at least one gate form a FET channel-gate coupling (150), through which the applied gate potential is arranged to control a current flowing through the semiconductor channel, and at least one space (200) disposed between the at least one gate and the semiconductor channel, wherein the at least one space is configured to receive a gas, Thereby, the gas received in the at least one space is arranged to affect at least one electrical characteristic of the FET channel-gate coupling, and wherein the FET gas sensor device is arranged to sense the gas based on the affected at least one electrical characteristic of the FET channel-gate coupling.

2. The FET gas sensor device according to claim 1, wherein The at least one gate, the semiconductor channel, the at least one space, and at least one of the source and the drain are arranged in a same plane.

3. The FET gas sensor device of claim 2, further comprising a substrate (145), wherein: The at least one gate, the semiconductor channel, the at least one space, and at least one of the source and the drain are arranged in a same plane parallel to a surface of the substrate.

4. The FET gas sensor device according to any of the preceding claims, further comprising at least one layer (300, 310, 320) disposed on at least a portion of the semiconductor channel, wherein The at least one layer includes a first layer (300) arranged to interact with a gas received in the at least one space.

5. The FET gas sensor device according to claim 4, wherein The at least one layer includes a portion disposed on a surface of the semiconductor channel facing the gate.

6. The FET gas sensor device according to claim 4 or 5, wherein: The first layer includes at least one metal.

7. The FET gas sensor device according to claim 6, wherein: This first layer includes one of the following: a film of at least one metal, Metal nanoparticles, and Nanoparticles of at least one metal selected from the group consisting of platinum Pt, palladium Pd, gold Au, and nickel Ni.

8. The FET gas sensor device according to any one of claims 4 to 7, wherein The at least one layer includes a second layer (310) disposed on at least a portion of the first layer, wherein the second layer includes at least one polymer and is arranged to protect the first layer from moisture.

9. The FET gas sensor device according to any one of claims 4 to 8, wherein The at least one layer includes a third layer (320), wherein the third layer is dielectric and is arranged to passivate a surface of the semiconductor channel.

10. The FET gas sensor device according to any one of claims 4 to 8 and 9, wherein The third layer is disposed on at least a portion of the semiconductor channel, and the first layer is disposed on at least a portion of the third layer.

11. The FET gas sensor device according to any one of claims 4 to 9 and 10, wherein The third layer has a thickness in the range of 0.5 nm to 10 nm.

12. The FET gas sensor device according to claim 11, wherein The third layer has a thickness in the range of 0.5 nm to 5 nm.

13. A FET gas sensor device according to any one of the preceding claims, wherein The semiconductor channel extends along an axis A, and wherein the FET gas sensor device comprises two gates (110a, 110b) arranged on opposite sides of the semiconductor channel perpendicular to the axis A.

14. A FET gas sensor device according to any one of the preceding claims, wherein: At least a portion of the semiconductor channel includes a nanowire.

15. The FET gas sensor device according to any one of the preceding claims, further comprising a substrate (145), wherein At least one of the at least one gate, the source, the drain, and the semiconductor channel is arranged on the surface of the substrate.

16. The FET gas sensor device according to claim 15, wherein The semiconductor channel is disposed over the surface of the substrate.

17. The FET gas sensor device according to any one of the preceding claims, further comprising a measuring unit configured to: measuring at least one electrical characteristic affected by the FET channel-gate coupling, and Gas is sensed based on the measured at least one affected electrical characteristic of the FET channel-gate coupling.

18. The FET gas sensor device according to claim 17, wherein The measuring unit is further configured to determine the concentration of molecular hydrogen H 2 in the gas based on the affected at least one electrical characteristic of the FET channel-gate coupling.

19. A FET gas sensor device according to any one of the preceding claims, wherein: The source, the drain and the semiconductor channel are formed from a same semiconductor material layer.

20. A FET gas sensor device according to any one of the preceding claims, wherein The at least one space is ≤500 nm.

21. A method (500) of sensing a gas by a field effect transistor (FET) gas sensor device (100), the field effect transistor (FET) gas sensor device comprising: at least one gate (110a, 110b); source (120); Drain (130); a semiconductor channel (140) arranged between the source and the drain, wherein the semiconductor channel and the at least one gate form a FET channel-gate coupling (150), through which the gate potential is arranged to control a current through the semiconductor channel; and at least one space (200) arranged between the at least one gate and the semiconductor channel, the method comprising: biasing (510) the source and the drain with a first voltage to generate a current flowing through the semiconductor channel, biasing (520) the gate with a second voltage and controlling current flowing through the semiconductor channel via a FET channel-gate coupling formed by the semiconductor and the at least one gate, receiving (530) a gas in the at least one space, whereby the gas received in the at least one space is arranged to affect at least one electrical characteristic of the FET channel-gate coupling, Gas is sensed (540) based on at least one affected electrical characteristic of the FET channel-gate coupling.

22. The method according to claim 21, further comprising: measuring at least one electrical characteristic affected by the FET channel-gate coupling, and Gas is sensed based on the measured at least one affected electrical characteristic of the FET channel-gate coupling.

23. The method according to claim 21 or 22, further comprising: Providing a layer on at least a portion of the semiconductor channel, wherein the layer comprises one of: a film of at least one metal, Metal nanoparticles, and Nanoparticles of at least one metal selected from the group consisting of platinum Pt, palladium Pd, gold Au, and nickel Ni, measuring the current through the semiconductor channel, and The concentration of molecular hydrogen H 2 in the gas is determined based on the measured current.

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