The present disclosure relates to the field of gas sensing. In particular, the present disclosure provides a high sensitivity semiconductor based hydrogen gas sensor using Palladium receptor.
BACKGROUND
[0002] Background description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed disclosure, or that any publication specifically or implicitly referenced is prior art. [0003] Hydrogen gas detection is an essential step in the alternative fuel manufacturing industry and other applications related to safety due to high inflammability and availability of hydrogen (low ignition energy of 0.02 mJ and wide explosive concentration range (4-75%) in air). Therefore a high sensitivity hydrogen gas sensor that would have desired performance characteristics would be useful for detection and monitoring of hydrogen gas leakage. However, due to properties such as molecular size, color and lack of odor of hydrogen gas, its containment, confinement, leakage and detection by human senses is very difficult.
[0004] Existing literature discusses improved DC characteristics of magnesium Silicide source Field Effect Transistors over traditional field effect transistors. Studies on gas sensing using capacitively coupled Platinum and Palladium metals to field effect transistors have been described in a literature. A gas sensing method based on work function measurement of the gas sensitive layer for detection of hydrogen, hydrogen sulphide and similar gases has been reported in another prior-art. Discussions on signal quality caused by change in work function of field effect transistors used in gas and humidity sensing appear in another literature. Another literatures describes a combination of MOSFET and SGFET used in gas sensing. However, none of the disclosed literatures demonstrate the combined effects of using Palladium metal gate electrodes and

Magnesium Silicide source electrode for improving sensitivity characteristics of hydrogen gas sensor.
[0005] The proposed hydrogen gas sensor operates on the principle of adsorption of hydrogen gas by Palladium gate electrodes capacitively coupled to the channel of a double gate field effect transistor, the change in gas pressure and concentration being proportional to the change in work function of the gas sensitive layer and correspondingly change in gate electrode potential. The source of the proposed field effect transistor pertains to magnesium silicide that is configured to form a heterojunction with the channel of the semiconductor FET. The heteroj unction facilitates tunneling of charge carriers from the source to the drain electrodes, the charge carriers being enabled to flow through the channel. Improved DC characteristics including sensitivity range, 'On' current, ratio of 'On' and 'Off current, threshold voltage and the likes are exhibited compared to traditional field effect transistors used as gas sensors.
OBJECTS OF THE PRESENT DISCLOSURE
[0006] Some of the objects of the present disclosure, which at least one
embodiment herein satisfies are as listed herein below.
[0007] It is an object of the present disclosure to provide a hydrogen gas
sensor that enables to obtain a set of desired performance attributes.
[0008] It is an object of the present disclosure to provide a hydrogen gas
sensor that pertains to a tunnel field effect transistor.
[0009] It is an object of the present disclosure to provide a hydrogen gas
sensor that enables the field effect transistor to have a source electrode, a drain
electrode and two control electrodes coupled to a semiconductor substrate.
[0010] It is an object of the present disclosure to provide a hydrogen gas
sensor that enables the control electrodes to be separated from the substrate by
one or more insulating layers of predetermined material.
[0011] It is an object of the present disclosure to provide a hydrogen gas
sensor that enables the source electrode to pertain to magnesium silicide material,

the point of contact between the semiconductor substrate and the source electrode
being configured to form a heterojunction.
[0012] It is an object of the present disclosure to provide a hydrogen gas
sensor that enables the control electrodes to pertain to Palladium receptors
configured to detect hydrogen gas.
[0013] It is an object of the present disclosure to provide a hydrogen gas
sensor that enables reaction between the Palladium receptors and hydrogen gas to
generate electric field at the control electrodes.
[0014] It is an object of the present disclosure to provide a hydrogen gas
sensor that enables flow of electric current from the source electrode to the drain
electrode through a semiconductor channel fabricated in the substrate by
tunneling.
SUMMARY
[0015] The present disclosure relates to the field of gas sensing. In particular,
the present disclosure provides a high sensitivity semiconductor based hydrogen
gas sensor using Palladium receptor.
[0016] An aspect of the present disclosure is to provide a hydrogen gas sensor
that may be enabled to attain a set of desired performance attributes, the attributes
pertaining to range of sensitivity, threshold voltage, 'On' current, ratio of 'On'
and 'Off current, sub-threshold and swing.
[0017] In an aspect the hydrogen gas sensor may pertain to a tunnel field
effect transistor with double gate or control electrode.
[0018] In an aspect, the field effect transistor may have a source electrode, a
drain electrode and two control electrodes coupled to a semiconductor substrate,
the coupling pertaining to one or more junctions.
[0019] In an aspect, the control electrodes may be separated from the substrate
by one or more insulating layers of predetermined material.
[0020] In an aspect the source electrode may pertain to magnesium silicide
material, the junction between the semiconductor substrate and the source

electrode being configured to form a staggered heterojunction facilitating
tunneling of charge carriers.
[0021] In an aspect the control electrodes may pertain to Palladium receptors
configured to detect hydrogen gas, the control electrodes being configured to react
with hydrogen gas and generate electric potential.
[0022] In an aspect the generated potential at the control electrodes of the
hydrogen gas sensor may enable flow of electric current from the source electrode
to the drain electrode through a semiconductor channel fabricated in the substrate.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0023] The accompanying drawings are included to provide a further
understanding of the present disclosure, and are incorporated in and constitute a
part of this specification. The drawings illustrate exemplary embodiments of the
present disclosure and, together with the description, serve to explain the
principles of the present disclosure.
[0024] The diagrams described herein are for illustration only, which thus are
not limitations of the present disclosure, and wherein:
[0025] FIG. 1 illustrates exemplary block diagram of the proposed high
sensitivity hydrogen gas sensor (100) using Palladium receptors, to elaborate upon
its working in accordance with an embodiment of the present disclosure.
[0026] FIG. 2A-2C illustrates exemplary views (200) of the proposed high
sensitivity hydrogen gas sensor (100) using Palladium receptors, in accordance
with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0027] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.

[0028] If the specification states a component or feature "may", "can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic. [0029] As used in the description herein and throughout the claims that follow, the meaning of "a," "an," and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise.
[0030] While embodiments of the present invention have been illustrated and described in the accompanying drawings, the embodiments are offered only in as much detail as to clearly communicate the disclosure and are not intended to limit the numerous equivalents, changes, variations, substitutions and modifications falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0031] The present disclosure relates to the field of gas sensing. In particular, the present disclosure provides a high sensitivity semiconductor based hydrogen gas sensor using Palladium receptor.
[0032] FIG. 1 illustrates exemplary block diagram of the proposed high sensitivity hydrogen gas sensor (100) using Palladium receptors, to elaborate upon its working in accordance with an embodiment of the present disclosure. [0033] In an embodiment, the proposed high sensitivity hydrogen gas sensor using Palladium receptors (100)(interchangeably known as sensor (100), herein) may include a semiconductor substrate (102). By way of example, the semiconductor substrate may pertain to intrinsic silicon material of predetermined dimensions. In an exemplary embodiment, the sensor (100) may pertain to a field effect transistor, the substrate (102) being configured to perform the functions of a conducting channel of the field effect transistor. The conducting channel may be enabled to facilitate flow of electric charge carriers constituting a current, the current being indicative of pressure of hydrogen gas detected by the sensor (100). [0034] In an embodiment, the sensors (100) may include one or more electrodes (104) coupled to the substrate (102), the points of contact between the

substrate (102) and the one or more electrodes (104) pertaining to one or more junctions having predefined gradient. The one or more electrodes (104) may include a source electrode and a drain electrode physically coupled to the substrate (102). The electric charge carriers may be enabled to flow from the source electrode to the drain electrode through the channel. By way of example, the source electrode may pertain to Magnesium Silicide material, the source region being positively doped. In an exemplary embodiment, the drain region may be negatively doped and may be made up of semiconductor material such as silicon. Doping concentrations of the source and the drain electrodes may be predetermined, and correspondingly the channel fabricated in the substrate may be of predetermined dimensions. The source and the drain electrodes may be configured to be fabricated on the substrate (02) material using one or more predefined semiconductor fabrication methods.
[0035] In an embodiment, the one or more electrodes (104) may include two control electrodes or gate electrodes that may be capacitively coupled to the substrate (102). By way of example, the control electrodes may be made up of Palladium that may perform functions of gas sensitive layer or receptor for hydrogen gas. The Palladium material may be enabled to react with hydrogen and correspondingly convert into Palladium hydride by a process known as adsorption of hydrogen. Generation of Palladium hydride may be facilitated to generate electric field or dipole at the control electrodes. Based on the pressure, concentration and the likes of hydrogen gas, strength of the generated electric field may change due to the change in work function voltage of the gas sensitive Palladium layer of the control electrodes. In an exemplary embodiment, the generated electric field at the control electrodes of gate electrodes may be enabled to facilitate movement of electric charge carriers from the source electrode to the drain electrode through the channel.
[0036] In an embodiment, the sensor (100) may include one or more insulating layers (106) of predetermined material that may be fabricated at the junctions between the gate electrodes pertaining to the one or more electrodes (104) and the substrate (102). By way of example the one or more insulating

layers (106) may pertain to Silicon dioxide material that may prevent the bidirectional flow of charge carriers between the control electrodes and the substrate (102) but may enable application of electric field at the gate electrodes that may be configured to control the flow of current through the channel in the substrate (102), the channel connecting the source and the drain electrodes. The one or more insulating layers (106) may have a capacitive effect pertaining to field effect transistors.
[0037] In an embodiment, the junction between the channel and the source electrode may pertain to type II staggered heterojunction that may enable in reducing tunneling barrier width configured to allow tunneling of larger number of electric charge carriers through the junction. In an embodiment, the combination of using Palladium control electrode and the Magnesiun Silicide source electrode may facilitate desired performance parameters such as ON current (ION), ION/IOFF ratio, Threshold Voltage(Vth) and subthreshold swing (SS) and range of sensitivity. By way of example, exemplary parametric values achieved by the proposed hydrogen sensors (100) may correspond to Table I. Table 1. Performance characteristics of the proposed device

Parameters Values
ION (A/u.m) 2.5 xlO4
IOFF (A/u.m) 6.06 xlO 18
ION/IOFF 4.12 x 1013
Vth(V) 0.26
SS (mV/decade) 10.05
[0038] FIG. 2A-2C illustrates exemplary views (200) of the proposed high sensitivity hydrogen gas sensor (100) using Palladium receptors, in accordance with an embodiment of the present disclosure.
[0039] In an illustrative embodiment of FIG 2A, the material-wise differences between the proposed semiconductor based hydrogen sensor and a traditional tunneling field effect transistor may be compared. In an embodiment, the combination of using Palladium control electrode and the Magnesium Silicide source electrode may facilitate desired performance parameters such as ON current (ION), ION/IOFF ratio, Threshold Voltage(Vth) and sub-threshold swing (SS)

and range of sensitivity. The desired performance parameters may enable the proposed hydrogen sensors (100) to exhibit higher range of sensitivity and higher responsivity at lower threshold voltages. Use of Palladium at the control or gate electrodes may facilitate in better adsorption of hydrogen gas. The heterojunction fabricated between the channel and the source electrode may enable lowering of tunneling width. Combination of a set of factors including use of Palladium and Magnesium Silicide may result in improved performance parameters. [0040] In an illustrative embodiment of FIG. 2B and 2C, detection of hydrogen by adsorption of hydrogen gas at the Palladium receptors pertaining to the gate electrodes may be observed. The Palladium gate electrodes may pertain to the gas sensitive layers that may react with hydrogen gas and generate Palladium Hydride. Correspondingly, generation of Palladium hydride may enable formation of dipoles in the gate electrode layers. The dipoles may facilitate generation of electric field at the control electrodes of the semiconductor based dual gate tunneling field effect transistor. Application of the electric field may correspondingly enable flow of charge carriers through the channel of the transistor substrate from the source electrode to the drain electrode. The Magnesium Silicide source may facilitate lowering of tunneling width necessary for the charge carriers and enable movement of larger number of charge carriers. [0041] As used herein, and unless the context dictates otherwise, the term "coupled to" is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with" are used synonymously. Within the context of this document terms "coupled to" and "coupled with" are also used euphemistically to mean "communicatively coupled with" over a network, where two or more devices are able to exchange data with each other over the network, possibly via one or more intermediary device.
[0042] The terms, descriptions and figures used herein are set forth by way of illustration only. Many variations are possible within the spirit and scope of the subject matter, which is intended to be defined by the following claims and their

equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated.
[0043] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
ADVANTAGES OF THE INVENTION
[0044] The present disclosure provides for a hydrogen gas sensor that enables
to obtain a set of desired performance attributes.
[0045] The present disclosure provides for a hydrogen gas sensor that pertains
to a tunnel field effect transistor.
[0046] The present disclosure provides for a hydrogen gas sensor that enables
the field effect transistor to have a source electrode, a drain electrode and two
control electrodes coupled to a semiconductor substrate.
[0047] The present disclosure provides for a hydrogen gas sensor that enables
the control electrodes to be separated from the substrate by one or more insulating
layers of predetermined material.
[0048] The present disclosure provides for a hydrogen gas sensor that enables
the source electrode to pertain to magnesium silicide material, the point of contact
between the semiconductor substrate and the source electrode being configured to
form a heterojunction.
[0049] The present disclosure provides for a hydrogen gas sensor that enables
the control electrodes to pertain to Palladium receptors configured to detect
hydrogen gas.

[0050] The present disclosure provides for a hydrogen gas sensor that enables reaction between the Palladium receptors and hydrogen gas to generate electric field at the control electrodes.
[0051] The present disclosure provides for a hydrogen gas sensor that enables flow of electric current from the source electrode to the drain electrode through a semiconductor channel fabricated in the substrate by tunneling.

We Claim:

1. A high-sensitivity hydrogen gas sensor using Palladium receptor (100), the
sensor being made up of a semiconductor electronic device, the device
comprising :
a substrate (102), configured to perform function of a base material for fabrication of the semiconductor electronic device, wherein after fabrication of the hydrogen gas sensor, the substrate pertains to a conducting channel, wherein the conducting channel is configured to allow flow of electric current through it;
one or more electrodes coupled to the substrate, wherein the one or more electrodes are fabricated on the substrate, wherein, the one or more electrodes pertain to one or more predetermined materials and one or more predetermined concentration of electric charge carriers, wherein one or more junctions are generated at the contact points between the substrate and the one or more electrodes due to fabrication;
one or more insulating layers deposited on the points of contact between the substrate and the one or more electrodes, wherein the one or more insulating layers pertain to predetermined material, wherein the one or more insulating layers restrict bidirectional flow of charge carriers between the substrate and the one or more electrodes.
2. The hydrogen gas sensor (100) as claimed in claim 1, wherein the
electronic device pertains to tunnel field effect transistor, wherein, the one
or more electrodes include two control electrodes, wherein the control
electrodes are physically separated from the substrate by the one or more
insulating layers, wherein change in one or more predetermined electrical
properties of the control electrodes correspond to flow of current through
the conducting channel.

The hydrogen gas sensor (100) as claimed in claim 2, wherein the one or more electrodes of the field effect transistor pertain to a source electrode, a destination or a drain electrode and the two control electrodes or gates, wherein hydrogen gas sensing is actuated by current flow from the source electrode to the drain electrode based on the electric field generated at the control electrodes.
The hydrogen gas sensor (100) as claimed in claim 3, wherein the source of the field effect transistor pertains to positively doped magnesium silicide, the drain pertains to negatively doped semiconductor material, the channel pertains to intrinsic semiconductor material and the two control electrodes pertain to Palladium deposited hydrogen receptive layer, wherein the hydrogen receptive layer is configured to react with hydrogen gas and generate the electric field configured to control current flow from source to drain electrodes through the conducting channel. The hydrogen gas sensor (100) as claimed in claim 2, wherein the source electrode pertaining to the field effect transistor is coupled to the conducting channel through a heterojunction, wherein electrical properties of the heterojunction reduces tunneling barrier pertaining to electric charge carriers, wherein the electric charge carriers correspond to the electric current flow from the source electrode to the drain electrode, the current flow being configured to generate electrical signals at the control electrodes.