METAL OXIDE THIN FILM, METHOD FOR DEPOSITING METAL OXIDE THIN FILM AND DEVICE COMPRISING METAL OXIDE THIN FILM

Abstract

A metal oxide thin film formed of β-MoO.sub.3 includes at least one doping element of the group Re, Mn, and Ru. Further, there is described a method of producing such a metal oxide thin film via sputtering and a thin film device with a metal oxide thin film of β-MoO.sub.3 that includes at least one doping element selected from the group Re, Mn, and Ru.

Claims

1-15. (canceled)

16. A metal oxide thin film, comprising a film formed of β-MoO.sub.3 including at least one doping element selected from the group consisting of Re, Mn, and Ru.

17. The metal oxide thin film according to claim 16, wherein a total doping content of said at least one doping element of the group Re, Mn, and Ru lies between 0<x≦10 at %.

18. The metal oxide thin film according to claim 17, wherein the total doping content of said at least one doping element of the group Re, Mn, and Ru lies between 1≦x≦3 at %.

19. The metal oxide thin film according to claim 16, wherein said at least one doping element is Re.

20. The metal oxide thin film according to claim 16, formed to have an electrical resistivity of below 104 Ω.Math.cm.

21. The metal oxide thin film according to claim 20, formed to have an electrical resistivity of below 103 Ω.Math.cm.

22. The metal oxide thin film according to claim 21, formed to have an electrical resistivity of below 102 Ω.Math.cm.

23. The metal oxide thin film according to claim 16, formed to have an internal optical transmittance to light in a visible range of more than 90%.

24. The metal oxide thin film according to claim 16, formed to have a refractive index of between 1.5 and 2.

25. The metal oxide thin film according to claim 16, wherein said film has a thickness of between 50 and 250 nm.

26. The metal oxide thin film according to claim 16, wherein said film has a thickness of between 1 and 15 nm.

27. A method of producing a metal oxide thin film, the method comprising the following steps: providing a substrate; providing a molybdenum target and a target comprising at least one element selected from the group consisting of Re, Mn, and Ru, or providing a target comprising molybdenum and at least one element selected from the group consisting of Re, Mn, and Ru; and sputtering the target or targets in an inert gas atmosphere.

28. The method according to claim 27, wherein the inert gas atmosphere comprises up to 40 vol % O.sub.2.

29. The method according to claim 27, further comprising a step of annealing.

30. A thin film device, comprising at least one metal oxide thin film according to claim 16.

31. The thin film device according to claim 30, which further comprises a substrate of glass or polymer.

32. An electrochromic window device or a touch panel device, comprising a metal oxide thin film according to claim 16.

Description

[0068] Further advantageous developments and configurations are provided by the following description of embodiments with reference to the accompanying drawings.

[0069] FIG. 1 Metal oxide thin films on substrates according to the first (a), second (b), third (c) and fourth (d) embodiment.

[0070] FIG. 2 Metal oxide thin film on substrate according to the eighth embodiment.

[0071] FIG. 3 Resistivity of β-MoO3 vs. doping content of Re in sputtered target in at % (First to fourth embodiment and comparative example 1).

[0072] FIG. 4 Resistivity of β-MoO3 vs. doping content of Re in metal oxide thin film in at % (First to fourth embodiment and comparative example 1). Because ReO3 is a volatile oxide, not all of the Re comprised in the sputtered target is included in the deposited thin film.

[0073] FIG. 5 Optical transmittance of Re-doped β-MoO3 compared to undoped β-MoO3 on a STO substrate (second embodiment).

[0074] FIG. 6 Resistivity β-MoO3 vs. doping content of Re in sputtered target in at % (left) and Resistivity of β-MoO3 vs. doping content of Re in metal oxide thin film in at % (right) according to the fifth embodiment. Because ReO3 is a volatile oxide, not all of the Re comprised in the sputtered target is included in the deposited thin film.

[0075] FIG. 7 Optical transmittance of Re-doped β-MoO3 on Al2O3 substrate (sixth embodiment).

[0076] FIG. 8 Refractive index and extinction coefficient of Re-doped β-MoO3 measured via ellipsometry.

COMPARATIVE EXAMPLE 1—UNDOPED β-MoO3

[0077] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a Mo target on an (100) oriented SrTiO3 (STO) substrate. The employed power was 2.5 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 2.5 sccm.

[0078] The thickness of the deposited film was approximately 60 nm. The actual Re content of the film was measured via EDX (energy dispersive X-ray spectrometry, JEOL scanning electron microscopy), and confirmed to be 0 at %. The resistivity of the deposited film was measured via four-point probe measurement at room temperature and 150° C. to be 5×10.sup.7 and 1×10.sup.6 Ω.Math.cm, respectively. These values can be found also in FIGS. 3 and 4. The optical transmittance of the deposited film was measured via spectrophotometer; the results are shown in FIG. 5.

FIRST EMBODIMENT

[0079] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a MoRe alloy target with a Re content of 3 at % on an (100) oriented SrTiO3 substrate. The employed power was 2.5 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 2.5 sccm.

[0080] The thickness of the deposited film was approximately 150 nm. The actual Re content of the film was measured via EDX being 0.25 at %. The resistivity of the deposited film was measured via four-point probe measurement at room temperature and 150° C. to be 5×10.sup.3 and 1×10.sup.2 Ω.Math.cm, respectively. These values can be found also in FIGS. 3 and 4.

SECOND EMBODIMENT

[0081] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a MoRe alloy target with a Re content of 6 at % on an (100) oriented SrTiO3 (STO) substrate. The employed power was 2.5 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 2.5 sccm.

[0082] The thickness of the deposited film was approximately 150 nm. The actual Re content of the film was measured via EDX being 1.81 at %. The resistivity of the deposited film was measured via four-point probe measurement at room temperature and 150° C. to be 9×10.sup.1 and 5 Ω.Math.cm, respectively. These values can be found also in FIGS. 3 and 4.

[0083] The optical transmittance of the deposited film was measured via spectrophotometer and compared to the film deposited in comparative example 1, the undoped β-MoO3 film. The results, as well as the transmittance of the STO substrate, are shown in FIG. 5 and it can easily be seen, that the internal optical transmittance of both samples (also the doped sample) is more than 90%.

THIRD EMBODIMENT

[0084] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a MoRe alloy target with a Re content of 10 at % on an (100) oriented SrTiO3 substrate. The employed power was 2.5 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 3 sccm.

[0085] The thickness of the deposited film was approximately 150 nm. The actual Re content of the film was measured via EDX being 1.30 at %. The resistivity of the deposited film was measured via four-point probe measurement at room temperature and 150° C. to be 5×10.sup.2 and 5×10.sup.1 Ω.Math.cm, respectively. These values can be found also in FIGS. 3 and 4.

FOURTH EMBODIMENT

[0086] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a MoRe alloy target with a Re content of 15 at % on an (100) oriented SrTiO3 substrate. The employed power was 2.5 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 4 sccm.

[0087] The thickness of the deposited film was approximately 160 nm. The actual Re content of the film was measured via EDX being 1.80 at %. The resistivity of the deposited film was measured via four-point probe measurement at room temperature and 150° C. to be 1×10.sup.3 and 1×10.sup.2 Ω.Math.cm, respectively. These values can be found also in FIGS. 3 and 4.

FIFTH EMBODIMENT

[0088] β-MoO3 thin films were deposited via reactive DC magnetron sputtering by using MoRe alloy targets with Re contents of 0, 3, 6, 10 and 15 at % on Al.sub.2O.sub.3 (012) oriented substrates. The employed power was 3.7 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was fixed to 7 sccm in a systematic approach. After deposition the films were annealed at 200° C. in air for 5 h.

[0089] The thickness of the deposited films was approximately 75 nm. The actual Re content of the film was measured via EDX. The resistivity of the deposited films was measured via four-point probe measurement at room temperature, the values can be found in FIG. 6. The measurement error for these measurements is far below 10 Ω.Math.cm.

[0090] With this systematic approach with fixed 02 flow rate of 7 sccm, the resulting resistivities were not as low as in the second embodiment, the lowest resistivity was 1×10.sup.2 Ω.Math.cm.

SIXTH EMBODIMENT

[0091] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a MoRe alloy target with a Re content 10 at % on an Al.sub.2O.sub.3 (012) oriented substrate. The employed power was 2.5 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 7 sccm. After deposition the films were annealed at 200° C. in air for 5 h. Transmittance of the as-deposited and annealed film was determined via spectrophotometer. Internal transmittance was determined to be more than 90% for both films. The results are shown in FIG. 7.

[0092] The thickness of the deposited films was approximately 80 nm. The resistivity of the deposited film was measured via four-point probe measurement at room temperature to be in the order of 10.sup.2 Ω.Math.cm.

SEVENTH EMBODIMENT

[0093] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a MoRe alloy target with a Re content 15 at % on a glass substrate. The employed power was 3.7 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 6 sccm. The internal transmittance of the film was determined via spectrophotometer. Internal transmittance was determined to be more than 90%.

[0094] The thickness of the deposited films was approximately 200 nm. The resistivity of the deposited film was measured via four-point probe measurement at room temperature to be 8×10.sup.2 Ω.Math.cm.

EIGHTH EMBODIMENT

[0095] A β-MoO3 thin film was deposited via reactive DC magnetron sputtering by using a MoRe alloy target with a Re content of 10 at % on an (100) oriented SrTiO3 substrate. The employed power was 2.5 W/cm.sup.2, pressure 1.0 Pa, deposition temperature 200° C. and the Ar flow rate was 10 sccm, O.sub.2 flow rate was 2 sccm.

[0096] The thickness of the deposited film was approximately 250 nm, the film is shown in FIG. 2. Because of the low O.sub.2 content, it is possible, that in addition to β-MoO3 the film of this embodiment also comprises small amounts of MoO2 and MoOx (2<x<3).