# US 7,608,467 B2 · Switchable resistive perovskite microelectronic device with multi-layer thin film structure

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- Number: US 7,608,467 B2
- Document ID: US7608467B2
- Status: Granted
- Kind: B2
- Application number: 11/034,695
- Filed: 2005-01-13
- Published: 2005-07-14
- Granted: 2009-10-27
- Earliest claimed: 2004-01-13
- Assignees: Board of Regents, University of Houston
- Inventors: Naijuan Wu; Xin Chen; Alex Ignatiev
- Web page: https://patentgrep.com/patent/US7608467B2

## CPC

- G11C 13/0007: {comprising metal oxide memory material, e.g. perovskites}
- H01C 7/006: {Thin film resistors}
- H10N 70/20: Multistable switching devices, e.g. memristors
- H10N 70/801: {Constructional details of multistable switching devices}
- H10N 70/826: {adapted for essentially vertical current flow, e.g. sandwich or pillar type devices}
- H10N 70/8836: {Complex metal oxides, e.g. perovskites, spinels}
- G11C 2213/31: Material having complex metal oxide, e.g. perovskite structure
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H01C: RESISTORS
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A switchable resistive device has a multi-layer thin film structure interposed between an upper conductive electrode and a lower conductive electrode. The multi-layer thin film structure comprises a perovskite layer with one buffer layer on one side of the perovskite layer, or a perovskite layer with buffer layers on both sides of the perovskite layer. Reversible resistance changes are induced in the device under applied electrical pulses. The resistance changes of the device are retained after applied electric pulses. The functions of the buffer layer(s) added to the device include magnification of the resistance switching region, reduction of the pulse voltage needed to switch the device, protection of the device from being damaged by a large pulse shock, improvement of the temperature and radiation properties, and increased stability of the device allowing for multivalued memory applications.

## Claims

### Claim 1

A method of using a two terminal multi-layer perovskite thin film resistance device comprising:
providing a switchable two terminal multi-layer perovskite thin film resistive device comprising:
a first electrode;
a second electrode;
a perovskite material thin film layer between the first and second electrodes;
a first insulating buffer layer between the perovskite material thin film layer and the first electrode; and
a second insulating buffer layer between the perovskite material thin film layer and the second electrode; and
selecting the perovskite material thin film layer to have a conductive partial gradient layer; and
using the conductive partial gradient layer as one of the electrodes.

### Claim 2 (depends on 1)

A method of claim 1, further comprising:
using the two terminal multi-layer perovskite thin film resistance device to make a random access or read only memory device.

### Claim 3 (depends on 1)

A method of claim 1, further comprising:
using the two terminal multi-layer perovskite thin film resistance device as a variable resistor in an electronic circuit.

### Claim 4 (depends on 1)

A method of claim 1, further comprising:
using the two terminal multi-layer perovskite thin film resistance device as a sensor for temperature, magnetic field, electric field or mechanical pressure measurements.

### Claim 5

A switchable two terminal multi-layer perovskite thin film resistive device comprising:
a first electrode;
a second electrode;
a perovskite material thin film layer between the first and second electrodes; and
a first insulating buffer layer between the perovskite material thin film layer and the first electrode.

### Claim 6 (depends on 1)

The device of claim 1, further comprising a second insulating buffer layer between the perovskite material thin film layer and the second electrode.

### Claim 7 (depends on 6)

A device as in claim 6, wherein the second insulating buffer layer comprises two insulating buffer layers.

### Claim 8 (depends on 1, 6, 7)

A device as in claims 1, 6 or 7, wherein the perovskite material thin film layer comprises a colossal magneto-resistance material.

### Claim 9 (depends on 7)

The device of claim 7, wherein the colossal magneto-resistance material comprises a material selected from the group consisting of LnBa(Co,M)2O5+x, ReBMnO3, ReBCoO3, and doped stoichiometric perovskites thereof, wherein Ln=Eu or Gd, M=Cu,Fe, Re is rare-earth ions, and B is alkaline ions.

### Claim 10 (depends on 1)

A device as in claim 1, in which the first buffer layer comprises two buffer layers.

### Claim 11 (depends on 1)

The device of claim 1, wherein the insulating buffer layer comprises a non-perovskite oxide material selected from the group consisting of SiO2, CeO2, MgO, ZnO, and Y2O3.

### Claim 12 (depends on 1)

The device of claim 1, wherein the insulating buffer layer comprises a doped non-perovskite oxide material selected from the group consisting of yttrium-stabled ZrO2 (YSZ), and (Sm,Gd) doped-CeO2.

### Claim 13 (depends on 1)

The device of claim 1, wherein the insulating buffer layer comprises a switchable perovskite oxide material selected from the group consisting of the high dielectric ACu3Ti4O12 family, colossal magneto-resistance materials, non-doped parent Mott-insulator materials, and polar materials, wherein A is selected from the group consisting of trivalent and rare earth ions.

### Claim 14 (depends on 1)

The device of claim 1, wherein the insulating buffer layer comprises a switchable perovskite oxide material selected from the group consisting of LaMnO3, Ba1−xSrxTiO3 (BST), Pb(Zr,Ti)O3 (PZT), La doped-PZT (PLZT), and Pb3Ge5O11 (PGO).