SEMICONDUCTOR DEVICE-BASED SENSORS AND METHODS ASSOCIATED WITH THE SAME
Semiconductor device-based chemical sensors and methods associated with the same are provided. The sensors include regions that can interact with chemical species being detected. The chemical species may, for example, be a component of a fluid (e.g., gas or liquid). The interaction between the chemical species and a region of the sensor causes a change in a measurable property (e.g., an electrical property) of the device. These changes may be related to the concentration of the chemical species in the medium being characterized.
1 . A FET-based chemical sensor designed to detect a chemical species comprising:
a semiconductor material region;
a source electrode formed on the semiconductor material region;
a drain electrode formed on the semiconductor material region;
a gate electrode formed on the semiconductor material region; and
a sensing region, separated from the gate electrode, and capable of interacting with the chemical species to change a measurable property of the chemical sensor.
2 . The sensor of claim 1 , wherein the sensing region comprises a sensing layer.
3 . The sensor of claim 2 , wherein the sensing layer has a thickness of less than 500 nm.
4 . The sensor of claim 2 , wherein the sensing region further comprises a surface region of the semiconductor material region positioned under the sensing layer.
5 . The sensor of claim 1 , wherein the sensing region comprises an exposed surface region of the semiconductor material region.
6 . The sensor of claim 1 , wherein the sensing region is formed between the source electrode and the drain electrode.
7 . The sensor of claim 1 , wherein a ratio of sensing electrode surface area to total channel surface area is greater than 0.35.
8 . The sensor of claim 1 , wherein the sensing region comprises a sensing electrode.
9 . The sensor of claim 8 , wherein a separate voltage may be applied to each of the source, drain, gate and sensing electrodes.
10 . The sensor of claim 1 , wherein respective electrical contacts to each of the source, drain, gate and sensing electrodes are formed on a backside of the sensor.
11 . The sensor of claim 1 , wherein the sensor is substantially free of electrical contacts on a frontside of the sensor in areas separate from the sensing region.
12 . The sensor of claim 1 , wherein the semiconductor region comprises a gallium nitride material layer.
13 . The sensor of claim 12 , wherein the sensing region is formed, at least in part, in the gallium nitride material layer.
14 . The sensor of claim 12 , wherein the gallium nitride material layer has a crack level of less than about 0.005 micron/micron 2 .
15 . The sensor of claim 1 , further comprising a substrate.
16 . The sensor of claim 15 , wherein the substrate is a silicon substrate.
17 - 28 . (canceled)
29 . A semiconductor device-based chemical sensor comprising:
a semiconductor material region;
a first electrode formed on the semiconductor material region;
a second electrode formed on the semiconductor material region;
a first electrical contact extending from a backside of the sensor to the first electrode;
a second electrical contact extending from a backside of the sensor to the second electrode; and
a sensing region, separated from the first electrode and the second electrode, and capable of interacting with the chemical species to change a measurable property of the chemical sensor.
30 . The chemical sensor of claim 29 , further comprising a third electrode, wherein the first electrode is a source electrode, the second electrode is a drain electrode and the third electrode is a gate electrode.
31 . A method of detecting chemical species comprising:
exposing a FET-based chemical sensor to a medium comprising chemical species; and
measuring changes in drain current of the sensor resulting from adsorption of the chemical species on a sensing region separated from the gate electrode to detect chemical species.
32 - 39 . (canceled)