US2017314156A1PendingUtilityA1

Method of liquid-phase epitaxial growth of lead zirconate titanate single crystals

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Assignee: QUEST INTEGRATED LLCPriority: Nov 30, 2012Filed: Jul 10, 2017Published: Nov 2, 2017
Est. expiryNov 30, 2032(~6.4 yrs left)· nominal 20-yr term from priority
Inventors:Vincent Fratello
C30B 29/32C30B 19/12C30B 19/04C30B 19/02H01L 41/18C30B 19/00H10N 30/095H10N 30/077
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Claims

Abstract

Growth of single crystals of lead zirconate titanate (PZT) and other perovskites is accomplished by liquid phase epitaxy onto a substrate of suitable structural and lattice parameter match. A solvent and specific growth conditions for stable growth are required to achieve the desired proportions of Zr and Ti.

Claims

exact text as granted — not AI-modified
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A lead zirconate titanate (PZT) single crystal having room temperature PZT lattice parameters comprising a=4.03±0.02 Å, c=4.15±0.02 Å, and b=4.03±0.02 Å, formed by a method comprising:
 providing a substrate in a solution, wherein the substrate has a perovskite crystal structure and one or more periodic repeat distances in the plane of growth that are integer multiples of the PZT periodic repeat distances of the same crystal orientation to within 2%, and wherein the solution comprises a solvent and a solute, and wherein the solute comprises PZT or PZT precursors PbO, TiO 2 , ZrO 2 , PbZrO 3  (PZ) and PbTiO 3  (PT); and 
 growing the PZT single crystal from the solution onto the substrate using liquid phase epitaxy, wherein the temperature of the solution is held to within 25° C. of a constant growth temperature; 
 wherein the liquid phase epitaxy is performed at a temperature of greater than 700° C. 
 
     
     
         2 . The PZT single crystal of  claim 1 , wherein the solvent includes a compound selected from the group consisting of PbF 2 , LiF, NaF, KF, Na 3 AlF 6 , PbO, Pb 3 (PO 4 ) 2 , PbCl 2 , B 2 O 3 , WO 3 , MoO 3 , V 2 O 5 , P 2 O 5 , PbWO 4 , PbMoO 4 , Li 2 B 4 O 7 , Na 2 B 4 O 7 , K 2 B 4 O 7 , and Pb 2 V 2 O 7 . 
     
     
         3 . The PZT single crystal of  claim 1 , wherein the PZT single crystal is of the monoclinic structure. 
     
     
         4 . The PZT single crystal of  claim 1 , wherein at least a portion of the PZT single crystal is in an unstable morphotropic phase boundary region and comprises a mixture of ferroelectric domains comprising one or more of the tetragonal, monoclinic, rhombohedral and orthorhombic crystal structures. 
     
     
         5 . The PZT single crystal of  claim 1 , wherein the substrate comprises a composition selected from the group consisting of a relaxor ferroelectric composition and a normal ferroelectric composition. 
     
     
         6 . The PZT single crystal of  claim 5 , wherein the substrate is grown by the Bridgman method. 
     
     
         7 . The PZT single crystal of  claim 5 , wherein the normal ferroelectric composition comprises lead titanate with an approximate composition of PbTiO 3  and the relaxor ferroelectric composition is selected from the group consisting of:
 lead magnesium niobate with an approximate composition of PbMg 1/3 Nb 2/3 O 3 ,   lead indium niobate with an approximate composition of PbIn 1/2 Nb 1/2 O 3 ,   lead ytterbium niobate with an approximate composition of PbYb 1/2 Nb 1/2 O 3 ,   a mixture of lead magnesium niobate and lead indium niobate, and   a mixture of lead magnesium niobate and lead ytterbium niobate.   
     
     
         8 . The PZT single crystal of  claim 1 , wherein the method further comprises removing the PZT single crystal from the substrate. 
     
     
         9 . The PZT single crystal of  claim 8 , wherein removing the PZT single crystal from the substrate comprises lapping and polishing. 
     
     
         10 . A method of growing a PZT single crystal having room temperature PZT lattice parameters comprising a=4.03±0.02 Å, c=4.15±0.02 Å, and b=4.03±0.02 Å using liquid phase epitaxy, comprising:
 providing a substrate in a solution, wherein the substrate has a perovskite crystal structure and one or more periodic repeat distances in the plane of growth that are integer multiples of the PZT periodic repeat distances of the same crystal orientation to within 2%, and wherein the solution comprises a solvent and a solute, and wherein the solute comprises PZT or PZT precursors PbO, TiO 2 , ZrO 2 , PbZrO 3  (PZ) and PbTiO 3  (PT); and 
 growing the PZT single crystal from the solution onto the substrate using liquid phase epitaxy, wherein the temperature of the solution is held to within 25° C. of a constant growth temperature; 
 wherein the liquid phase epitaxy is performed at a temperature of greater than 700° C. 
 
     
     
         11 . The method of  claim 10 , wherein the solvent includes a compound selected from the group consisting of PbF 2 , LiF, NaF, KF, Na 3 AlF 6 , PbO, Pb 3 (PO 4 ) 2 , PbCl 2 , B 2 O 3 , WO 3 , MoO 3 , V 2 O 5 , P 2 O 5 , PbWO 4 , PbMoO 4 , Li 2 B 4 O 7 , Na 2 B 4 O 7 , K 2 B 4 O 7 , and Pb 2 V 2 O 7 . 
     
     
         12 . The method of  claim 10 , wherein at least a portion of the PZT single crystal is in an unstable morphotropic phase boundary region and comprises a mixture of ferroelectric domains comprising one or more of the tetragonal, monoclinic, rhombohedral and orthorhombic crystal structures. 
     
     
         13 . The method of  claim 10 , wherein the PZT single crystal is of the monoclinic structure. 
     
     
         14 . The method of  claim 10 , wherein the substrate comprises a composition selected from the group consisting of a relaxor ferroelectric composition and a normal ferroelectric composition. 
     
     
         15 . The method of  claim 14 , wherein the substrate is grown by the Bridgman method. 
     
     
         16 . The method of  claim 14 , wherein the normal ferroelectric composition comprises lead titanate with an approximate composition of PbTiO 3  and the relaxor ferroelectric composition is selected from the group consisting of:
 lead magnesium niobate with an approximate composition of PbMg 1/3 Nb 2/3 O 3 ,   lead indium niobate with an approximate composition of PbIn 1/2 Nb 1/2 O 3 ,   lead ytterbium niobate with an approximate composition of PbYb 1/2 Nb 1/2 O 3 ,   a mixture of lead magnesium niobate and lead indium niobate, and   a mixture of lead magnesium niobate and lead ytterbium niobate.   
     
     
         17 . The method of  claim 10 , wherein the solubilities of titanium oxide and zirconium oxide in the solution are equal. 
     
     
         18 . The method of  claim 10 , wherein the PZT single crystal comprises Pb(Zr 0.52 Ti 0.48 )O 3 . 
     
     
         19 . The method of  claim 10 , wherein the solubilities of PT and PZ in the solution are equal. 
     
     
         20 . A PZT single crystal formed by the method of  claim 10 .

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