Amorphous TiOx Bolometer Resistance Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional uncooled infrared detector bolometers, particularly those using vanadium oxide (VOx), suffer from resistance instability and memory effects due to Joule or infrared heating, leading to pixel-to-pixel variations and increased production costs, while alternative materials like titanium oxide (TiOx) lack defined structures or compositions that impact their properties.
Innovation Solution
A bolometer with an amorphous TiOx layer having a composition ratio 'x' between 1.68 and 1.95, which is annealed at a predetermined temperature to achieve high resistance stability and low 1/f noise, overcoming the instability issues of VOx and providing compatible resistance values with read-out electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanadium oxide (VOx) is used as the bolometer material, then high Temperature Coefficient of Resistance (TCR) and adequate resistance are achieved, but resistance instability and memory effects occur under Joule or infrared heating
Solution Approach 1:
The patent changes the material composition parameter from conventional VOx to titanium oxide (TiOx) with a specific oxygen-to-titanium ratio, fundamentally altering the electrical and thermal properties to eliminate memory effects while maintaining high TCR and resistance stability under heating conditions
Solution Approach 2:
The invention uses a composite structure consisting of a titanium oxide layer deposited on a suspended membrane, combining the high TCR properties of TiOx with the thermal isolation characteristics of the suspended structure to achieve stable bolometric operation without resistance drift
2Reliability
If pure titanium or titanium alloy is used to achieve specific resistance near 47 μΩ-cm and low TCR of 0.3%, then lower 1/f noise is achieved, but the resistor must be very long and serpentine in shape, occupying significant space
Solution Approach 1:
The patent changes the resistance and TCR parameters by selecting titanium oxide instead of pure titanium, achieving a balance between moderate TCR (higher than titanium but lower than VOx) and adequate resistance, which allows for more compact resistor geometries with lower 1/f noise
Solution Approach 2:
The invention applies different materials to different functional regions: titanium oxide is used specifically for the resistive bolometer element where controlled TCR and low noise are needed, while other structures can be optimized independently, allowing compact integration
3Ease of operation
If conventional VOx bolometers are used, then high TCR and adequate resistance are achieved, but resistance varies with long decay time to equilibrium and permanent residual resistance change under heating
Solution Approach 1:
The patent fundamentally changes the material's thermal and electrical parameters by using titanium oxide, which has different thermal conductivity and heat capacity characteristics, resulting in faster thermal response and elimination of permanent resistance changes after heating cycles
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
The amorphous TiOx layer with x in the range of 1.68 to 1.95 exhibits high resistance stability, low 1/f noise, and improved compatibility with read-out circuitry, reducing resistance drift and memory effects, thus enhancing the performance and yield of uncooled infrared detectors.
Implementation Method 1
The TiOx layer after formation over the substrate may be heated at a predetermined temperature for a predetermined period such that the TiOx layer has a substantially constant resistance stability
Implementation Method 2
exposing microbolometers (pixels) manufactured from VOx to Joule heating or infrared heating results in the resistance of the microbolometers varying
Data Source
AI summary
A bolometer is provided for use in an infrared imager. The bolometer comprises a substrate and a TiOx layer formed over the substrate. The TiOx layer has a resistance responsive to temperature. The x value of the TiOx layer is in the range of 1.68 to 1.95.