CN101560642A - Method for preparing In2O3 transparent conductive film with high mobility doped with Mo - Google Patents

Abstract

The invention relates to a method for preparing an In2O3 transparent conductive film with high-mobility doped with Mo (namely In2O3: Mo-IMO) by electron beam evaporation technology. The growth of the IMO film by the technology is divided into two stages, wherein a high-purity ceramic target In2O3:MoO3 and O2 are taken as raw materials, and the temperature of a substrate is between 330 and 400 DEG C. The method comprise the following steps: growing a layer of buffer layer IMO film at the low velocity of between 0.1 and 0.2*/s by the technology, wherein the thickness of the film is between 30 and 40 nanometers; and secondly, improving the growth velocity to be between 0.4 and 1.0 */s, and growing an IMO film at high velocity, wherein the thickness of the film is between 50 and 80 nanometers. The typical film resistivity is 2.5*10<-4>omega cm; the square resistance is 22.5 omega; the carrier concentration is 5.8*10<20>omega cm; the electron mobility is 47.1 cm<2>V<-1>s<-1>; and the average transmission of visible light and near infrared regions is 80 percent. The photoelectric properties of the IMO film obtained by the technology are equivalent to or better than that of a film which is grown by utilization of low velocity, and the growth time of the film is greatly reduced.

Description

A kind of preparation high mobility doped with Mo In 2O 3The method of transparent conductive film

[technical field]:

The invention belongs to the transparent conductive oxide film technical field, particularly be fit to the preparation method of the transparent conductive film of thin film solar cell application.

[background technology]:

The optical bandwidth of amorphous silicon hydride (a-Si:H) is about 1.7eV, its uptake factor is higher in the shortwave direction, and the optical bandwidth of microcrystalline hydrogenated silicon (μ c-Si:H) is about 1.1eV, its uptake factor is higher in the long wave direction, and can absorb the near infrared Long wavelength region, absorbing wavelength can extend to 1100nm, and this just makes solar spectrum can obtain more good utilisation.Fig. 1 has provided optical wavelength and the relation between absorption intensity and the uptake factor (Fig. 1 a is the graph of a relation of photon energy and absorption intensity, and Fig. 1 b is the graph of a relation of uptake factor and photon wavelength) of a-Si:H, μ c-Si:H material.In addition, than amorphous silicon thin-film materials, microcrystalline silicon film material structure order degree height, therefore, the microcrystalline silicon film battery has good device stability, does not have obvious decay.This shows that microcrystalline silicon solar cell can utilize the near infrared light zone of solar spectrum preferably, and novel a-Si:H/ μ c-Si:H laminated film solar battery will be expanded the solar spectrum range of application, whole stability test and the efficient of improving ^[1-2]

According to the Drude theory, the optical characteristics of near-infrared region is closely related with the carrier concentration of material, and the square root of its plasma frequency and free carrier concentration is proportional ^[3]:

${\mathrm{\&omega;}}_p=\sqrt{4\mathrm{\&pi;}{n}_e{e}^2/m*}.$

Wherein, ω _p-plasma frequency, n _e-electron density, e-elementary electronic charge, m*-effective electron mass.If the higher absorption that has then strengthened near infrared light of carrier concentration.Therefore, based on μ c-Si:H and a-Si:H/ μ c-Si:H laminate film battery applications, wish preceding electrode TCO in the p-i-n type battery structure at visible-range and near infrared region high permeability and keep high conductivity, valid approach is to prepare low carrier concentration and the TCO film of high mobility.Utilize the poor (Mo of high valence state ⁶⁺And In ³⁺The valence state difference be 3) adulterated In ₂O ₃: Mo (Mo doping In ₂O ₃, i.e. IMO) and film adapted to application development in this respect.

The method of growth IMO film is a lot of at present, comprises radio frequency/d.c. sputtering (RF/DC Sputtering), electric beam evaporation (EBRE), pulsed laser deposition technique (PLD) etc.Calendar year 2001, the Meng Yang of Fudan University ^[4-6]Deng having reported that novel high mobility TCO film-IMO (is Mo doping In ₂O ₃, In ₂O ₃: Mo), be characterized in utilizing the poor (Mo of high valence state ⁶⁺And In ³⁺The valence state difference be 3) low-doped enough free carriers that provides mix to be provided, effectively reduce ionized impurity scattering, improve electronic mobility.Typical case IMO electronic mobility 80-130cm ²/ Vs, resistivity～1.8-3 * 10 ^-4Ω cm, the visible light average transmittances is better than and the near-infrared region (average transmittances of λ=800-1400nm) all～more than 80%, film thickness～250-400nm wherein.E.Elangovan etc. ^[7]Utilized radio-frequency sputtering technical study power and film thicknesses etc. are to In ₂O ₃: the influence of Mo-IMO membrane structure and photoelectric properties, the lowest resistivity of IMO film are 2.65 * 10 ^-3Ω cm, and high mobility obtains numerical value～19.5cm at decrystallized film ^2/Vs.C.Warmsinhg etc. ^[8]Utilize the pulsed laser deposition technique In that on glass substrate and monocrystalline 100YSZ (yttria-stabilized zirconia) substrate, grown ₂O ₃: Mo, i.e. IMO film, experiment shows that the film of 2wt.%Mo doping target preparation has best film characteristics, can obtain the thin film electronic mobility on the YSZ single-crystal substrate and reach～95cm ²/ Vs, through normalized obtain the IMO film in visible-range transmitance greater than 90%.C.C.Kuo etc. ^[9]Utilize ion beam assisted deposition to study oxygen partial pressure to In ₂O ₃: the influence of Mo film microstructure and photoelectric properties, FE-SEM test shows IMO has columnar structure, the AFM test data shows that its r.m.s. roughness is 2nm, oxygen flow increases the resistivity that can reduce the IMO film, the IMO film that obtains when at 5sccm oxygen flow and ion beam voltage 150V has optimum performance, and lowest resistivity is 1.59 * 10 ^-3Ω cm, electronic mobility～16.31cm ²/ Vs, carrier concentration～1.02 * 10 ²⁰/ cm ³Shi-Yao Sun etc. ^[10]Utilize the high density plasma evaporation technique to prepare molybdenum doped indium oxide (IMO) film, the target of use is for mixing MoO ₃In ₂O ₃Oxide target wherein contains 2wt.%MoO ₃During preparation IMO film at Ar and O ₂Add certain amount of H in the mixed gas ₂, add H ₂The rear film mobility increases, and film resiativity obviously reduces and the process window broadening, but adds H ₂Film is reduced in the transmitance of visible region.The Miu Weina of Fudan University (Wei-na miao) etc. ^[11]Oxygen partial pressure, substrate temperature and the sputtering current influence to IMO membrane structure and optical property that utilized the magnetically controlled DC sputtering technical study, the lowest resistivity that obtains the IMO film is 3.65 * 10 ^-4Ω cm, carrier mobility is up to 50cm ²/ Vs, the average transmittance of visible region (containing substrate of glass) is higher than 80%, and wherein the carrier mobility of IMO film mainly is subjected to the influence of crystal boundary scattering.

In film growth techniques, promptly to improve growth velocity, reduce the film growth time, can guarantee that again the material photoelectric properties are important topics of research.The present invention utilizes electron beam evaporation technique, by gradient growth velocity technology, prepares the high mobility of high growth rates and excellent property, and high electricity is led the IMO film with high permeability.

[summary of the invention]:

The objective of the invention is to solve the relatively poor relatively problem of film performance under the high speed deposition condition, a kind of electron beam evaporation technique that utilizes is provided, prepare the method for high mobility IMO transparent conductive film by the gradient growth velocity.

The Mo doping In of preparation high mobility provided by the invention, high conductivity and visible light and near infrared region high permeability ₂O ₃The method of transparent conductive film is to utilize the electric beam evaporation technology, is realized by following steps:

The first, high purity ceramic target In ₂O ₃: MoO ₃(MoO ₃Content is the adulterated In of 0.5%-2% weight ratio ₂O ₃, mix as 0.5% weight ratio) and O ₂As source material, base substrate temperature T=330-400 ℃ (as 350 ℃, 380 ℃); O ₂Dividing potential drop 5.0-9.0 * 10 ^-2Pa is as 7.7 * 10 ^-2Pa;

The second, at first, utilize electron beam evaporation technique low rate on glass substrate

(as

) growth one deck buffer layer Mo doping In ₂O ₃Film, film thickness 30-40nm (as d=30nm); Secondly, on above-mentioned buffer layer basis, two-forty again

(as ) film of growth 50-80nm (as d=50nm) thickness; Growing film structure: glass/ low rate buffer layer IMO/ two-forty IMO film.

Advantage of the present invention and positively effect:

The present invention utilizes the method for gradient growth velocity, is guaranteeing to utilize low speed buffer layer technology under the higher growth velocity condition, prepare with the low rate condition under identical or better film characteristics, and greatly reduced the film growth time.

The IMO film of growing under (gradient growth velocity) condition, film rectangular resistance is 22.5 Ω, resistivity is 2.5 * 10 ^-4Ω cm, carrier concentration is 5.8 * 10 ²⁰Cm ^-3, electronic mobility reaches 47.1cm ²V ^-1s ^-1, visible light and near infrared range average transmittances～80% (containing 2mm thickness glass substrate).

[description of drawings]:

Fig. 1 has provided optical wavelength and the relation between absorption intensity and the uptake factor (Fig. 1 a is the graph of a relation of photon energy and absorption intensity, and Fig. 1 b is the graph of a relation of uptake factor and photon wavelength) of a-Si:H, μ c-Si:H material.

Fig. 2 is that growth velocity is respectively

With

The IMO film surface appearance figure that grows under (gradient growth velocity) condition.(Fig. 2 a is that growth velocity is

The IMO film surface appearance figure that grows under the condition; Fig. 2 b is that growth velocity is

The IMO film surface appearance figure that grows under the condition; Fig. 2 c is that growth velocity is The IMO film surface appearance figure that grows under (gradient growth velocity) condition.)

Fig. 3 is that growth velocity is

With The transmittance curve of the IMO film of growing under (gradient growth velocity) condition.

[embodiment]:

Embodiment 1:

The concrete manufacturing processed of the growth IMO film process that the present invention proposes is as follows:

1, electron beam evaporation technique is initially at low rate

Growth IMO film 30nm under the condition is as buffer layer;

2, secondly, under the constant situation of other growth conditionss, two-forty on above-mentioned buffering basis

Growth 50nmIMO film, the film that final growth obtains is the IMO film of 80nm thickness, membrane structure: glass/

-30nm/

-50nm; Above-mentioned thickness is the thickness of quartz resonator test in the film growth system, and the film thickness of actual measurement is 110nm.

Typical growth conditions is as follows: electron beam evaporation technique growth IMO film, and the glass substrate area is 10cm * 10cm, growth temperature is set at 350 ℃, background vacuum pressure 3.0 * 10 ^-3Pa feeds high-purity O ₂Operating air pressure 7.7 * 10 during gas ^-2Pa utilizes high purity In ₂O ₃: MoO ₃Target (MoO ₃: 0.5% weight ratio), electron beam gun operating voltage 6380V, electronic beam current 14-22mA (low rate

Employing～14mA and two-forty

Adopt～22mA).

Film performance is seen accompanying drawing 2, accompanying drawing 3 and table 1.As can be seen, membrane structure is glass/

-IMO/

In the sample of-IMO, the film grain-size is bigger, and film is at the transmitance and the low rate growth glass/ of visible-range

The transmitance of-IMO film is suitable, and than two-forty growth glass/

The transmitance height of-IMO film.In addition, under the situation of equal film thickness, gradient speed growth glass/ The square resistance of-IMO film is minimum, and electronic mobility is the highest, and film has good electric property.

Table 1 growth velocity is respectively

With

The electric property of the IMO film of growing under (gradient growth velocity) condition

Embodiment 2

The concrete manufacturing processed of film:

1, electron beam evaporation technique is initially at low rate Growth IMO film 40nm under the condition is as buffer layer;

2, secondly, under the constant situation of other growth conditionss, two-forty on above-mentioned buffering basis

Growth 60nmIMO film, the IMO film of the 70nm thickness of finally growing, membrane structure: glass/

-20nm/ -60nm; Above-mentioned thickness is the thickness of quartz resonator test in the film growth system, actual (real) thickness 120nm.

Typical growth conditions is as follows: electron beam evaporation technique growth IMO film, and the glass substrate area is 10cm * 10cm, growth temperature is set at 350 ℃, background vacuum pressure 3.0 * 10 ^-3Pa feeds high-purity O ₂Operating air pressure 7.7 * 10 during gas ^-2Pa utilizes high purity In ₂O ₃: MoO ₃Target (MoO ₃: 0.5% weight ratio), electron beam gun operating voltage 6380V, electronic beam current 14-22mA (low rate

Employing～14mA and two-forty Adopt～22mA).

Reference

[1]J.Meier，S.Dubail，R.Platz，etc.Solar?Energy?Materials?and?Solar?Cells，49(1997)35.

[2]Arvind?Shah，J.Meier，E.Vallat-Sauvain，etc.Thin?Solid?Films，403-404(2002)179.

[3]V.Sittinger，F.Ruske，W.Werner，etc.Thin?Solid?Films?496(2006)16.

[4]Y.Meng，X.L.Yang，H.X.Chen，etc.Thin?Solid?films，394(2001)219.

[5]Y.Meng，X.L.Yang，H.X.Chen，etc.J.Vac.Sci.Tech.A，20(2002)288.

[6] Meng Yang, Yang Xiliang, Chen Huaxian etc., photoelectron technology, 21 (2001) 17.

[7]E.Elangovan，A.Marques，A.S.Viana，etc.Thin?Solid?Films，516(2008)1359.

[8]C.Warmsingh，Y.Yoshida，and?D.W.Readey，etc.Journal?of?Applied?Physics，95(2004)3831.

[9]C.C.Kuo，C.C.Liu，C.C.Lin，etc.Vacuum，82(2008)441.

[10]Shi-Yao?Sun，Jow-Lay?Huang，Ding-Fwu?Lii.Thin?Solid?Films，469-470(2004)6.

[11] Li Xifeng, Miu Weina, Zhang Qun etc., vacuum science and technology journal, 25 (2005) 142.

Claims (1)

1, a kind of Mo doping In for preparing high mobility, high conductivity and visible light and near infrared region high permeability ₂O ₃The method of transparent conductive film is characterized in that this method utilizes the electric beam evaporation technology, is realized by following steps:

The first, high purity ceramic target In ₂O ₃: MoO ₃And O ₂As source material, base substrate temperature T=330-400 ℃; O ₂Dividing potential drop 5.0-9.0 * 10 ^-2Pa; Described high purity ceramic target In ₂O ₃: MoO ₃Be MoO ₃Content is the adulterated In of 0.5%-2% weight ratio ₂O ₃

The second, at first, utilize electron beam evaporation technique low rate on glass substrate

Growth one deck buffer layer Mo doping In ₂O ₃Film, film thickness 30-40nm; Secondly, on above-mentioned buffer layer basis, two-forty again The film of growth 50-80nm thickness; Growing film structure: glass/ low rate buffer layer IMO/ two-forty IMO film.

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