Capacitor, and device comprising the same, and method of preparing the same
A capacitor may include a first thin-film electrode layer; a second thin-film electrode layer; and a dielectric layer between the first thin-film electrode layer and the second thin-film electrode layer. The first thin-film electrode layer and the second thin-film electrode layer may include a conductive perovskite-type crystal structure. The dielectric layer may include a metal oxide having a dielectric perovskite-type crystal structure. The dielectric layer may be an epitaxial layer. The metal oxide may include a first element in a cubooctahedral site, a second element in an octahedral site, and a third element in an octahedral site. A valency of the third element may be lower than a valency of the second element, and the third element may be a dopant.
1 . A capacitor comprising:
a first thin-film electrode layer;
a second thin-film electrode layer; and
a dielectric layer between the first thin-film electrode layer and the second thin-film electrode layer,
wherein the first thin-film electrode layer and the second thin-film electrode layer each have a conductive perovskite-type crystal structure,
the dielectric layer includes a metal oxide having a dielectric perovskite-type crystal structure, and the dielectric layer is an epitaxial layer,
wherein the metal oxide includes a first element in a cubooctahedral site, a second element in an octahedral site, and a third element in an octahedral site,
wherein a valency of the third element is lower than a valency of the second element, and
the third element is a dopant.
2 . The capacitor of claim 1 , wherein the valency of the second element is 4 or more, and the third element has a valency of 3 or less.
3 . The capacitor of claim 1 , wherein the third element is at least one of Y, Mg, Ni, Fe, Mn, Co, Al, Cr, Bi, Cr, and Ga.
4 . The capacitor of claim 1 , wherein ionic radii of the third element are greater than ionic radii of the second element.
5 . The capacitor of claim 1 , wherein
the metal oxide is a ternary metal oxide, and
a crystal lattice of the metal oxide has a compressive strain along c-axis.
6 . The capacitor of claim 5 , wherein
in the crystal lattice of the metal oxide, a c-axis lattice constant is larger than at least one of an a-axis lattice constant and a b-axis lattice constant, and
the c-axis lattice constant is about 3.96 Å to about 4.20 Å.
7 . The capacitor of claim 1 , wherein
a content of the third element is about 0.1 at % to about 9 at % with respect to a total sum of the second element and the third element.
8 . The capacitor of claim 1 , wherein the dielectric layer comprises a metal oxide represented by Formula 1 below:
A1 1-a D1 a B1 1-b C1 b O 3-δ Formula 1
wherein in Formula 1,
0≤a<1, 0.001<b<0.09, and 0≤δ≤0.5,
A1 and D1 each are an element with a valency of 2,
B1 is an element with a valency of 4, and
C1 is an element with a valency of 1, an element with a valency of 2, or an element with a valency of 3.
9 . The capacitor of claim 5 , wherein C1 is at least one of Y, Mg, Ni, Fe, Mn, Co, Al, Cr, Bi, Cr, and Ga.
10 . The capacitor of claim 1 , wherein the dielectric layer comprises a metal oxide represented by Formula 2 below:
Ba 1-a Sr a Ti 1-b C2 b O 3-δ Formula 2
wherein, in Formula 2,
0<a<1, 0.001<b<0.08, and 0≤δ≤0.5,
wherein C2 is at least one of Y, Mg, Ni, Fe, Mn, Co, Al, Cr, Bi, Cr, and Ga.
11 . The capacitor of claim 1 , wherein
on an XRD spectrum of the dielectric layer, a rocking curve is observed by θ scan between an X-ray source and a sample surface,
the rocking curve has a first peak on (200) plane at a diffraction angle of θ=22.5°±0.5°, and
a full width at half maximum (FWHM) of the first peak is 0.1° or less.
12 . The capacitor of claim 1 , wherein
a ratio (εr2/εr1) of a first relative permittivity (εr1) at a thickness of 100 Å of the dielectric layer to a second relative permittivity (εr2) at a thickness of 50 Å of the dielectric layer is 0.2 or more.
13 . The capacitor of claim 1 , wherein
the dielectric layer has a thickness of about 10 Å to about 500 Å,
the dielectric layer has at least one of a flat-plate structure, a trench structure, and a pillar structure, and
the dielectric layer has a monolayer membrane structure or a multilayer membrane structure.
14 . The capacitor of claim 1 , wherein
the first thin-film electrode layer, the second thin-film electrode layer, or both the first thin-film electrode layer and the second thin-film electrode layer comprise a ternary metal oxide,
the ternary metal oxide comprises the first element,
the first thin-film electrode layer, the second thin-film electrode layer, or both the first thin-film electrode layer and the second thin-film electrode layer independently comprise at least one of SrRuO 3 , SrVO 3 , SrNbO 3 , SrMnO 3 , SrCrO 3 , SrFeO 3 , SrCoO 3 , SrMoO 3 , SrIrO 3 , SrCoO 3 , CaRuO 3 , CaNiO 3 , BaRuO 3 , and (Ba,Sr)RuO 3 .
15 . The capacitor of claim 1 , further comprising:
an interlayer, wherein
the interlayer is between the first thin-film electrode layer and the dielectric layer, between the second thin-film electrode layer and the dielectric layer, or the interlayer is between the first thin-film electrode layer and the dielectric layer and the interlayer is between the second thin-film electrode layer and the dielectric layer,
wherein the interlayer has a same type of crystal structure as at least one of the first thin-film electrode layer, the second thin-film electrode layer, and the dielectric layer,
wherein the first thin-film electrode layer, the second thin-film electrode layer, and the dielectric layer are in contact with the interlayer,
wherein a composition of the interlayer is different from a composition of the first thin-film electrode layer, a composition of the second thin-film electrode layer, and a composition the dielectric layer.
16 . The capacitor of claim 15 , wherein the interlayer has a perovskite-type crystal structure, and
the interlayer comprises a metal oxide represented by Formula 3, a metal oxide represented by Formula 4, or a metal oxide represented by Formula 5:
A2B2O 3-δ1 Formula 3
wherein in Formula 3,
A2 is an element with a valency of 2,
B2 is an element with a valency of 1, an element with a valency of 2, or an element with a valency of 3,
1.5≤δ1≤3.0
A3B3O 3-δ2 Formula 4
wherein in Formula 4,
A3 is an element with a valency of 1,
B3 is an element with a valency of 4, and
1.5≤δ2≤3.0
A4B4O 3-δ3 Formula 5
wherein in Formula 5,
A4 is an element with a valency of 3,
B4 is an element with a valency of 3, and
2.5≤δ3≤3.0.
17 . The capacitor of claim 15 , wherein
the interlayer comprises a metal oxide selected from among
SrGaO 3-δ1 , CaGaO 3-δ1 , BaGaO 3-δ1 , MgGaO 3-δ1 , BeGaO 3-δ1 ,
SrInO 3-δ1 , CaInO 3-δ1 , BaInO 3-δ1 , MgInO 3-δ1 , BeInO 3-δ1 ,
SrBeO 3-δ1 , CaBeO 3-δ1 , BaBeO 3-δ1 , MgBeO 3-δ1 ,
SrMgO 3-δ1 , CaMgO 3-δ1 , BaMgO 3-δ1 , BeMgO 3-δ1 ,
SrBaO 3-δ1 , CaBaO 3-δ1 , MgBaO 3-δ1 , BeBaO 3-δ1 ,
SrCaO 3-δ1 , BaCaO 3-δ1 , MgCaO 3-δ1 , BeCaO 3-δ1 ,
SrLiO 3-δ1 , CaLiO 3-δ1 , BaLiO 3-δ1 , MgLiO 3-δ1 , BeLiO 3-δ1 ,
SrNaO 3-δ1 , CaNaO 3-δ1 , BaNaO 3-δ1 , MgNaO 3-δ1 , BeNaO 3-δ1 ,
SrKO 3-δ1 , CaKO 3-δ1 , BaKO 3-δ1 , MgKO 3-δ1 , BeKO 3-δ1 ,
SrRbO 3-δ1 , CaRbO 3-δ1 , BaRbO 3-δ1 , MgRbO 3-δ1 , BeRbO 3-δ1 ,
LiTiO 3-δ2 , NaTiO 3-δ2 , KTiO 3-δ2 , RbTiO 3-δ2 ,
LiZrO 3-δ2 , NaZrO 3-δ2 , KZrO 3-δ2 , RbZrO 3-δ2 ,
LiHfO 3-δ2 , NaHfO 3-δ2 , KHfO 3-δ2 , and RbHfO 3-δ2 ,
ScAlO 3-δ3 , YAlO 3-δ3 , LaAlO 3-δ3 , CeAlO 3-δ3 , PrAlO 3-δ3 , NdAlO 3-δ3 , SmAlO 3-δ3 , DyAlO 3-δ3 ,
ScGaO 3-δ3 , YGaO 3-δ3 , LaGaO 3-δ3 , CeGaO 3-δ3 , PrGaO 3-δ3 , NdGaO 3-δ3 , SmGaO 3-δ3 , DyGaO 3-δ3 ,
ScInO 3-δ3 , YInO 3-δ3 , LaInO 3-δ3 , CeInO 3-δ3 , PrInO 3-δ3 , NdInO 3-δ3 , SmInO 3-δ3 , and DyInO 3-δ3 ,
wherein 1.5≤δ1≤3.0, 1.5≤δ2≤3.0, and 2.5≤δ3≤3.0.
18 . The capacitor of claim 15 , wherein
the interlayer has a thickness of about 1 Å to about 20 Å,
a Schottky Barrier Height (SBH) between the dielectric layer and the first thin-film electrode layer or second thin-film electrode layer is 1.5 eV or more, and
the interlayer is an epitaxial layer.
19 . A device comprising
the capacitor according to claim 1 .
20 . The device of claim 19 , wherein the device comprises a memory device, a logic device, or an energy storage device.
21 . A method of preparing a capacitor, the method comprising:
forming a dielectric layer on one side of a first thin-film electrode layer by epitaxy growth; and
forming a second thin-film electrode layer on the dielectric layer to thereby provide the capacitor,
wherein the capacitor includes the dielectric layer between the first thin-film electrode layer and the second thin-film electrode layer,
wherein the first thin-film electrode layer and the second thin-film electrode layer have a conductive perovskite-type crystal structure,
the dielectric layer includes a metal oxide having a dielectric perovskite-type crystal structure,
the metal oxide includes a first element in a cubooctahedral site, a second element in an octahedral site, and a third element in an octahedral site,
a valency of the third element is lower than a valency of the second element, and
the third element is a dopant.
22 . The method of claim 21 , wherein the epitaxy growth is conducted at a temperature of 600° C. or less.
23 . The method of claim 21 , further comprising:
before the forming the dielectric layer,
forming an interlayer on the one side of the first thin-film electrode layer by epitaxy growth.