CNT Bolometer Gate Sweeping for Stable TCR Detection
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Solution Overview
Problem
Existing bolometers using semiconducting carbon nanotubes (CNTs) face challenges in achieving stable and high temperature coefficient of resistance (TCR) due to hysteresis in drain current measurements.
Innovation Solution
A bolometer design incorporating a gate electrode, drain electrode, source electrode, and a first film made of carbon nanotubes, with a gate voltage swept periodically between an upper and lower limit value, and optionally including oxide particles and a second film for doping, to stabilize TCR measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If semiconducting carbon nanotubes are used in the bolometer, then the temperature coefficient of resistance (TCR) is enhanced, but hysteresis occurs in drain current measurements causing instability
Solution Approach 1:
The patent applies periodic sweeping of the gate voltage between upper and lower limit values to eliminate hysteresis effects in the drain current measurements. This periodic action resets the measurement state and ensures stable TCR values by operating in a consistent region of the carbon nanotube's electrical characteristics.
Solution Approach 2:
The patent changes the gate voltage parameter dynamically by sweeping it between defined limit values. This parameter change strategy allows the system to operate in a controlled manner, selecting specific regions of the carbon nanotube's transfer characteristics that provide stable and reproducible TCR measurements while avoiding hysteresis-prone regions.
2Reliability
If the gate voltage is swept with periodicity between upper and lower limit values, then measurement stability is improved, but device complexity increases
Solution Approach 1:
The periodic sweeping of gate voltage is implemented as a simple control strategy that can be achieved through basic voltage source programming. The upper and lower limit values are predetermined, making the control logic straightforward while effectively eliminating hysteresis and improving measurement stability.
Solution Approach 2:
The system uses the measured drain current as feedback to determine TCR values at specific points during the gate voltage sweep. By measuring at predetermined gate voltage values within the swept range, the system obtains stable readings that can be used for infrared detection without requiring complex real-time control algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Stabilizes TCR measurements by allowing detection at the timing when the absolute value of TCR increases, achieving high and stable TCR values with reduced resistance.
Implementation Method 1
a gate electrode to which a gate voltage is capable of being applied... the gate voltage is swept with a periodicity between an upper limit value and a lower limit value
Implementation Method 2
semiconducting carbon nanotubes (CNTs)... improvement of an infrared sensor is enhanced using semiconducting carbon nanotubes (CNTs)... Stabilizes TCR measurements
Implementation Method 3
a drain electrode to which a drain voltage is capable of being applied... applying a drain voltage to the drain electrode
Data Source
AI summary
A bolometer includes a gate electrode to which a gate voltage is capable of being applied, a drain electrode to which a drain voltage is capable of being applied, a source electrode, and a first film connecting the drain electrode and the source electrode and including carbon nanotubes. The gate voltage is swept with a periodicity between an upper limit value and a lower limit value.