Large temperature coefficient of resistance material
First Claim
1. A temperature sensor structure comprising a single crystal substrate;
- a buffer layer comprising CeO2 deposited over the substrate and YBCO deposited over the CeO2 buffer layer; and
an epitaxial thin film of an oxide material having a perovskite-like structure which undergoes a ferromagnetic phase transition.
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Accused Products
Abstract
Oxide thin films having a perovskite-like structure and undergoing a ferromagnetic phase transition with large temperature coefficients of resistance (TCRs) are disclosed. These can be useful materials for making thermistors, bolometers, infrared detectors and the like. These can be fabricated with a number of methods, preferably including metal oxide chemical vapor deposition, laser ablation and sputtering. In one embodiment, the oxides are based on a LaMnO3 with substitutions of Ca, Sr, Ba, Mn, and Pb for some of the La. The amounts can be varied to maximize the TCR or shift the temperature at which the maximum occurs. Methods of making such thin films are disclosed. In one embodiment, the high sensitivity films can be used in an array of micro-bolometers in an infrared camera.
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Citations
12 Claims
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1. A temperature sensor structure comprising a single crystal substrate;
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a buffer layer comprising CeO2 deposited over the substrate and YBCO deposited over the CeO2 buffer layer; and
an epitaxial thin film of an oxide material having a perovskite-like structure which undergoes a ferromagnetic phase transition. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A bolometer having a substrate comprising a silicon nitride layer;
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a biaxially textured YSZ buffer layer deposited on said silicon nitride layer;
a YBCO buffer layer deposited on said YSZ buffer layer; and
a temperature sensing layer deposited thereon, said temperature sensing layer comprising an oxide material having a perovskite structure that undergoes a ferromagnetic phase transition. - View Dependent Claims (8, 9, 10, 11, 12)
A is a divalent atom selected from an alkaline earth metal, or Mn or Pb, B is a divalent atom selected from an alkaline earth metal, or Mn, or Pb, and where w+x+y=1, w, x and y are in the range of 0 to 1, and z is in the range of 2-3.5. -
10. The bolometer of claim 9 wherein A is Ca, B is Pb, w is about 0.6 and x ranges from about 0.2 to about 0.3.
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11. The bolometer of claim 7 wherein:
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the substrate comprises;
a silicon nitride layer;
a biaxially textured YSZ buffer layer deposited on said silicon nitride layer;
a CeO2 buffer layer deposited on said biaxially textured YSZ layer;
a YBCO buffer layer deposited on said CeO2 buffer layer; and
the oxide material has the chemical formula LawCaxPbyMnOz where w is about 0.6 and x ranges from about 0.2 to about 0.3.
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12. The bolometer of claim 7 wherein the oxide material is further characterized by having a temperature coefficient of resistance greater than about 8% at temperatures greater than about 270°
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Specification