Large temperature coefficient of resistance material

• US 6,337,991 B1
• Filed: 11/05/1997
• Issued: 01/08/2002
• Est. Priority Date: 11/05/1996
• Status: Expired due to Fees

• Current Assignee: Corning Applied Technologies (Corning Incorporated)
• Original Assignee: Corning Applied Technologies (Corning Incorporated)
• Inventors: Li, Yi-Qun, Zhao, Jing
• Primary Examiner(s): Utech, Benjamin L.
• Assistant Examiner(s): ANDERSON, MATTHEW A
• Application Number:
  US08/964,520
• Time in Patent Office: 1,525 Days
• Field of Search: 117/947, 117/84, 117/99, 428/446, 252/62.51 R, 252/62.3 T, 252/519.1, 338/22.R, 338/25, 338/22.SD, 505/161, 505/238, 505/825, 505/842, 505/847
• US Class Current: 505/161
• CPC Class Codes: C30B 23/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/22 Complex oxides
• CPC Class Codes: C30B 29/225 based on rare earth copper oxides, e.g. high T-superconductors
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 31/03046 including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
• CPC Class Codes: H01L 31/101 Devices sensitive to infrared, visible or ultraviolet radiation
• CPC Class Codes: H10N 15/00 Thermoelectric devices without a junction of dissimilar materials; Thermomagnetic devices, e.g. using the Nernst-Ettingshausen effect integrated devices or assemblies of multiple devices H10N19/00
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials

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.

Claims

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.

2. The structure of claim 1 wherein the substrate is selected from a single crystal which is lattice matched to the oxide material.

3. The structure of claim 2 wherein the single crystal is (100) oriented lanthanum aluminate.

4. The structure of claim 1 wherein the substrate is a single crystal which is not lattice matched to the oxide material.

5. The structure of claim 4 wherein the buffer layers comprise CeO₂ deposited on the substrate and further comprises YBCO deposited on the CeO₂ buffer layer.

6. The temperature sensor of claim 1 wherein the oxide material is further characterized by having a temperature coefficient of resistance greater than about 8% at temperatures greater than about 270°

K.

7. A bolometer having a substrate comprising a silicon nitride layer;

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.

8. The bolometer claim 7 additionally comprising a CeO₂ buffer layer deposited on said biaxially textured YSZ layer and interposed between said YSZ layer and said YBCO layer.

9. The bolometer of claim 7 wherein the oxide material has the chemical formula La_wA_xB_yMnO_z where

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.

11. The bolometer of claim 7 wherein:

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 La_wCa_xPb_yMnO_z where w is about 0.6 and x ranges from about 0.2 to about 0.3.

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°

K.