Transparent conducting films including complex oxides
Transparent conducting films including an alkaline earth, transition metal oxide and their optimization of electrical conductivity and optical transparency by aliovalent substitution, which are useful as electrodes for semiconductors and other electronic devices are disclosed. Such materials include thin films of an aliovalent substituted transition metal oxides of Formula (I): A 1-x A′ x B 1-y B′ y O 3-d (I) or a transition metal oxide of Formula (II): (ABO 3-d )m(A′B′O 3-d′ )n.
1. A transparent conducting film having a transmittance of about 80% or more at a wavelength of 550 nm comprising a transition metal oxide of formula:
A 1-x A′ x B 1-y B′ y O 3-d (I)
wherein A and A′ are different from each other and A represents one or more divalent alkaline earth cations; A′ represents either one or more trivalent cations or one or more monovalent cations; B and B′ are different from each other and B represents a transition metal selected from group VB; d is a value between −0.5≤d≤0.5; and the values for x and y are 0≤x≤1, 0≤y≤1; and
wherein B′ is present and represents one or more group VIB transition metal elements to adjust a Fermi level position in a conduction band of the transition metal oxide.
2. The film according to claim 1 , wherein A′ is present and represents one or more of a trivalent cation of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium to adjust a Fermi level position in a conduction band of the transition metal oxide.
3. The film according to claim 1 , wherein A′ is present and represents one or more of a monovalent ion of lithium, sodium, potassium, rubidium or cesium to adjust a Fermi level position in a conduction band of the transition metal oxide.
4. The film according to claim 1 characterized by an electron mobility of about 1˜100 cm 2 /V/sec and/or a carrier density of about 1×10 21 ˜2×10 23 cm −3 , and/or a thickness in the range of about 5 to 50 nm.
5. An electrode material comprising at least one transparent conducting film according to claim 1 .
6. An electrode comprising the electrode material of claim 5 on a substrate.
7. The electrode according to claim 6 , wherein the substrate is silicon, germanium, or a compound semiconductor with zinc blende or wurtzite crystal structure, with or without a thin transparent coating.
8. The electrode according to claim 6 , wherein the substrate is a glass substrate, a plastic substrate, or an oxide deposited substrate, and has transmittance.
9. The film according to claim 1 having a conductivity of about 2000 S/cm (resistivity 5×10 −4 Ω×cm) to about 100000 S/cm (resistivity 1×10 −6 Ω×cm) at room temperature.
10. The film according to claim 1 , wherein A represents one or more of Mg, Ca, Sr, or Ba; A′ represents one or more of La, Nd, Gd, Dy, or another rare earth element; B represents one or more of V, Nb, or Ta, B′ represents one or more of Cr, Mo or W.
11. The film according to claim 10 , wherein 0.8≤y≤1.0 and 0<x≤0.2.
12. The film according to claim 1 , wherein A′ and B′ are present, A′ represents La, or another rare earth element; A represents one or more of Mg, Ca, Sr, or Ba; B represents one or more of V or Nb; B′ represents one or more of Mo or W.
13. A transparent conducting film comprising a transition metal oxide of formula:
(ABO 3-d ) m (A′B′O 3-d′ ) n (II)
wherein A and A′ are different from each other and A represents one or more divalent alkaline earth cations; A′ represents either one or more trivalent cations or one or more monovalent cations; B and B′ are different from each other and B represents a transition metal selected from group VB; and B′ represents a transition metal from the groups VB, IVB, VIB, IVA and/or group IIIA; d and d′ have values of −0.5≤d≤0.5 and −0.5≤d′≤0.5, respectively, and 1≤m≤10 and 1≤n≤10; and
wherein the film has a transmittance of about 80% or more at a wavelength of 550 nm and a conductivity of about 2000 S/cm (resistivity 5×10 −4 Ω×cm) to about 100,000 S/cm (resistivity 1×10 −6 Ω×cm) at room temperature.
14. The film according to claim 13 , wherein d and/or d′ are within the limits of −0.2≤d≤0.2 and −0.2≤d′≤0.2.
15. The film according to claim 13 , wherein B′ represents one or more group VIB transition metal elements to adjust a Fermi level position in a conduction band of the transition metal oxide.
16. The film according to claim 13 , wherein A and A′ represent one or more of Sr or Ca; B represents one or more of V or Nb; B′ represents one or more of V, Nb, Ta, or Mo.