High breakdown strength ferroelectric SrHfO3 materials

Patent metadata

Field	Value
Publication number	US-11335845-B2
Application number	US-201916255069-A
Country	US
Kind code	B2
Filing date	Jan 23, 2019
Priority date	Jan 23, 2018
Publication date	May 17, 2022
Grant date	May 17, 2022

Abstract

Methods for making metastable lead-free piezoelectric materials are presented herein.

First claim

What is claimed is:

1. A ferroelectric induced piezoelectric material having a piezoelectric response (d 33 ) of greater than about 5.2 pm V −1 wherein the piezoelectric material comprises a metastable SrHfO 3 polymorph with a P4 mm structure and wherein the polymorph is grown on a substrate suitable for epitaxial growth of the polymorph; and wherein the substrate is SrTiO 3 .

2. The material of claim 1 wherein the polymorph has a breakdown strength of greater than about 25 MV/cm.

3. The material of claim 1 wherein the polymorph is capable of a piezoelectric response (e 33 ) of at least 8.8 C m −2 .

4. The material of claim 1 having an average coercive field of about 83 kVcm −1 and a remnant polarization of about 1.2 μCcm −2 .

5. The material of claim 1 wherein the polymorph is epitaxially stabilized by a substrate upon which the polymorph is grown.

6. A method for making a lead-free piezoelectric material comprising the steps of using pulsed laser deposition to grow epitaxial films from a SrHfO 3 target on a SrTiO 3 substrate wherein the lead-free piezoelectric material has a response of 5.2 pm V −1 for a 35 nm film, wherein the film comprises a metastable SrHfO 3 polymorph with a P4 mm structure and identifying the lead-free piezoelectric material comprising a piezoelectric tensor (e ij max ) of greater than 3 C m −2 by using density functional theory (DFT); and identifying a substrate that is capable of epitaxially stabilizing the piezoelectric material.

7. The method of claim 6 wherein the growth takes place at a temperature of greater than about 450° C.

8. The method of claim 6 wherein the growth takes place at a total pressure of about 100 mTorr oxygen.

9. The method of claim 6 wherein the growth takes place by using a pulse rate of the laser of between about 10 and about 40 Hz.

10. The method of claim 6 wherein the lead-free piezoelectric material has a breakdown strength of greater than about 25 MV/cm.

11. The method of claim 6 wherein the lead-free piezoelectric material is a film that is capable of a ferroelectric-induced large signal effective converse piezoelectric response of 5.2 pm V −1 .

12. The method of claim 6 wherein the lead-free piezoelectric material has an average coercive field of about 83 kVcm −1 and a remnant polarization of about 1.2 μCcm −2 .

Assignees

• Alliance Sustainable Energy
• Lawrence Berkeley Nat Laboratory
• Penn State Res Found
• Univ California

Inventors

• Garten Lauren Marie
• Ginley David Samuel
• Ceder-Persson Kristin Aslaug
• Dwaraknath Shyam Sundar
• Trolier-Mckinstry Susan

Classifications

• C30B29/22 Primary

  Complex oxides · CPC title

• C30B23/025

  characterised by the substrate · CPC title

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C01G27/00

  Compounds of hafnium · CPC title

• C30B23/066

  Heating of the material to be evaporated · CPC title