CN102345104A - Preparation method of colossal magnetoresistance effect Fe-Ti-O amorphous film - Google Patents

Abstract

A preparation method of a colossal magnetoresistance effect Fe-Ti-O amorphous film adopts an ultra-high vacuum three-target codeposition magnetron sputtering coating machine for the preparation, and comprises the following steps: 1) mounting a Ti target and a Fe target on a target head of the coating machine respectively; 2) mounting a glass substrate on a substrate support; 3) turning on the magnetron sputtering device to vacuumize a sputtering chamber; 4) introducing mixed gas of O2 and Ar into the vacuum chamber to obtain a vacuum degree of 1 Pa of the vacuum chamber; 5) turning on a sputtering direct-current power supply, applying a current and a voltage to the Ti target and the Fe target; 6) opening a baffle plate of the substrate, rotating the substrate support, growing a film on the substrate; 7) after the sputtering is completed, injecting nitrogen into the vacuum chamber to obtain the prepared target product. The advantages of the invention are that: the process method is simple and easy to carry out, and the prepared film has high room-temperature magnetoresistance effect; the production cost is low, and the method is applicable to large-scale popularization and application.

Description

A kind of preparation method of Fe-Ti-O amorphous film with large magnetoresistance effect

technical field

The invention relates to a semiconductor material preparation technology, in particular to a method for preparing a large magnetoresistance effect Fe-Ti-O amorphous film.

Background technique

In 1988, he discovered the giant magnetoresistance effect (Giant Magnetoresistance, GMR) in the Fe/Cr magnetic multilayer film. This work won the 2007 Nobel Prize in Physics. Since then, many novel physical phenomena have been discovered in heterogeneous magnetic systems (multilayer films, granular films, tunnel junctions, etc.), such as tunnel magnetoresistance (TMR), giant Hall effect, high coercive force, high frequency soft magnetism, etc. Therefore, the study of spin-dependent electron transport properties and magnetic properties in inhomogeneous magnetic systems has become one of the most active research topics in the fields of materials science and condensed matter physics in recent years.

Inhomogeneous magnetic systems, such as antiferromagnetically coupled magnetic multilayer films, magnetic metal-nonmagnetic metal, magnetic metal-insulator granular film systems, and research on giant magnetoresistance (GMR) in magnetic tunnel junctions have gradually formed. An emerging interdisciplinary subject - spintronics (Spintronics). Spintronics is expected to achieve high integration and low power consumption compared to existing information processing using positive and negative charges by applying the property that electron spins exist in two different states (up and down) to information processing , Electronic components with high processing speed. The research on spintronics materials and devices can be roughly divided into three stages, that is, the research on GMR and TMR magnetoresistance effects and their devices represented by magnetic multilayer films, granular films, tunnel junctions and spin valves; and the research phase of spin-dependent transport properties in dilute magnetic semiconductors; and the applied research phase of preparing spintronic devices.

Tian Yufeng and others observed a large positive magnetoresistance effect at low temperature (5K) in the Co-ZnO nanoparticle film, the maximum value can reach 811%, and the value of the magnetoresistance is closely related to the content of Co in the film. They think that the positive magnetoresistance The emergence of the effect is related to the suppression of spin-dependent variable-range transitions by the spin Zeeman effect [ApplPhysLett92(2008)192109.]. A German research group found a positive magnetoresistance of 31% at 5K in 3d metal-doped ZnO films [Thin Solid Films, 2006, 515: 2549.]. The research team of Tohoku University in Japan discovered the low-temperature large magnetoresistance phenomenon in Co-C60 composite films, which can reach 85% at the maximum under appropriate current [Appl Phys Lett, 2006, 89: 113118.]. Professor Liu Yihua from the Department of Physics of Shandong University found a significant enhancement effect of magnetoresistance in Fe-In ₂ O ₃ particle films [JPhys: Condens Matter, 2003, 15: 47.]. The magnetoresistance effect in these new systems will be candidates for novel spintronic devices. However, the physical mechanism of the magnetoresistance effect and its variation in these magnetic metal element-semiconductor systems is still unclear, and systematic and in-depth research is needed to clarify its microscopic physical mechanism and provide a theoretical basis for its design in spintronic devices. At the same time, it enriches people's understanding of the magnetoresistance effect. In previous studies, the research results of the magnetoresistance effect of magnetic metal elements doped titanium dioxide thin films were not given.

Contents of the invention

The purpose of the present invention is to provide a kind of preparation method of Fe-Ti-O amorphous film with large magnetoresistance effect for above-mentioned technical analysis, and this process method technology is simple, easy to implement, and the film that makes has higher room temperature magnetoresistance Effect; low production cost, suitable for large-scale popularization and application.

Technical scheme of the present invention:

A method for preparing a large magnetoresistance effect Fe-Ti-O amorphous film is prepared by using an ultra-high vacuum three-target co-deposition magnetron sputtering coating machine. The steps are as follows:

1) Install a Ti target and an Fe target on the target head of the coating machine;

2) After removing impurities on the surface of the glass substrate, install it on the substrate frame with the substrate at the top and the target at the bottom, and the distance between the substrate and the target is 13cm;

3) Turn on the magnetron sputtering equipment, start the first-level mechanical pump and the second-level molecular pump to vacuumize until the vacuum degree of the back and bottom of the sputtering chamber is greater than 8.5×10 ^-6 Pa;

4) feed into the vacuum chamber the mixed gas of O _and Ar, so that the degree of vacuum in the vacuum chamber is 1Pa;

5) Turn on the sputtering DC power supply, apply current and voltage on the Ti target and Fe target respectively, pre-sputter for 20 minutes, and wait for the sputtering current and voltage to stabilize;

6) Open the baffle plate of the substrate, and simultaneously rotate the substrate holder at a rate of 2 revolutions per minute, and grow an iron-doped titanium dioxide amorphous film on the substrate;

7) After growing the film for 15 minutes, close the baffle plate of the substrate, stop the rotation of the substrate holder, then turn off the sputtering power supply, stop feeding the sputtering gas Ar and O ₂ , continue vacuuming for half an hour, then close the vacuum system, and then turn off the sputtering power supply. The vacuum chamber is filled with nitrogen with a purity of 99.999%, until the air pressure in the vacuum chamber is the same as the outside atmospheric pressure, and then the vacuum chamber is opened to take out the prepared target product.

The purity of the Ti target and the Fe target are both 99.99%, the thickness of the Ti target is 4 mm, the thickness of the Fe target is 2.5 mm, and the diameters of the Ti target and the Fe target are both 60 mm.

In the mixed gas of O ₂ and Ar, the purity of O ₂ and Ar are both 99.999%, wherein the flow rate of O ₂ is 3 sccm, and the flow rate of Ar is 100 sccm.

The sputtering DC power supply applied a current of 0.4A and a voltage of 340V to the Ti target, and applied a current of 0.3A and a voltage of 320V to the Fe target.

The preparation method of a large magnetoresistance effect Fe-Ti-O amorphous thin film involved in the present invention has the advantages of compatibility with existing industrial production, simple target selection and preparation conditions, etc., and can be used in the preparation of various electronic devices. It has wide application value.

Compared with other methods for preparing thin films, the present invention has the following advantages:

1) The present invention adopts sputtering method to prepare Fe-Ti-O amorphous film with large room temperature magnetoresistance effect, compared with conventional pulse laser deposition method and organic metal chemical vapor deposition method, it has obvious advantages in industrial production Cost and technical advantages;

2) The process conditions are simple, no substrate heating is required, no special substrate materials are required, and it can be realized on a glass substrate, which is not only easier to realize industrially, but also has a wider range of applications;

3) The film has a high room temperature magnetoresistance effect.

Description of drawings

Fig. 1 is a high-resolution transmission electron microscope bright field image of the Fe-Ti-O amorphous thin film prepared in the present invention.

Fig. 2 is the relationship curve of the resistance of the Fe-Ti-O amorphous thin film prepared in the present invention as a function of temperature.

Fig. 3 is the relationship curve of the magnetoresistance of the Fe-Ti-O composite thin film prepared in the present invention with the external magnetic field and temperature (the magnetic field is perpendicular to the film surface).

Detailed ways

Example:

According to the structure and property analysis that we carried out to the sample prepared in the present invention, the best embodiment of the iron-doped titanium dioxide amorphous film preparation with large room temperature magnetoresistance effect will be described in detail below, used in the embodiment The magnetron sputtering equipment is an ultra-high vacuum three-target co-deposition magnetron sputtering coating machine produced by the Shenyang Scientific Instrument Development Center of the Chinese Academy of Sciences.

A preparation method of a large magnetoresistance effect Fe-Ti-O amorphous film, the steps are as follows:

1) Install a Ti target with a purity of 99.99% and an Fe target with a purity of 99.99% respectively on the target head of the coating machine, the thickness of the target material is 4mm and 2.5mm respectively, and the diameter is 60mm;

2) After removing impurities on the surface of the glass substrate by ultrasonic waves, install the substrate on the substrate frame with the substrate at the top and the target at the bottom, and the distance between the substrate and the target is 13 cm;

3) Turn on the magnetron sputtering equipment, start the first-level mechanical pump and the second-level molecular pump to vacuumize until the vacuum degree of the back and bottom of the sputtering chamber is greater than 8.5×10 ^-6 Pa;

4) feed the mixed gas of 99.999% _O2 and 99.999% Ar to the vacuum chamber, so that the vacuum in the vacuum chamber is 1Pa, wherein _O2 The flow rate is 3 sccm, and the Ar flow rate is 100 sccm;

5) Turn on the sputtering DC power supply, apply a current of 0.4A and a voltage of 340V to the Ti target, and apply a current of 0.3A and a voltage of 320V to the Fe target, pre-sputter for 20 minutes, and wait for the sputtering current and voltage to stabilize ;

6) Open the baffle plate of the substrate, and simultaneously rotate the substrate holder at a rate of 2 revolutions per minute, and grow an iron-doped titanium dioxide amorphous film on the substrate;

7) After growing the film for 15 minutes, close the substrate baffle and the substrate holder rotation system, then turn off the sputtering power supply, stop feeding the sputtering gas Ar and O ₂ , continue vacuuming, and turn off the vacuum system after half an hour. The vacuum chamber is filled with nitrogen gas with a purity of 99.999%, until the air pressure in the vacuum chamber is the same as the outside atmospheric pressure, and then the vacuum chamber is opened to take out the sample.

In order to confirm the best embodiment of the present invention, we have carried out the analysis of atomic force microscope, the relationship of resistance with temperature and the relationship of magnetoresistance with external magnetic field for the film prepared in the present invention.

Fig. 1 is a high-resolution transmission electron microscope bright field image of the Fe-Ti-O amorphous thin film prepared in the present invention. It can be seen from the figure that the sample is a disordered amorphous state, and there is no long-range order.

Fig. 2 is the relationship curve of the resistance of the Fe-Ti-O amorphous thin film prepared in the present invention as a function of temperature. It can be seen from the figure that the resistance of the sample increases with the decrease of temperature, showing the characteristics of semiconductor conductivity.

Fig. 3 is the relationship curve of the magnetoresistance of the Fe-Ti-O composite thin film prepared in the present invention with the external magnetic field and temperature (the magnetic field is perpendicular to the film surface). It can be seen from the figure that the magnetoresistance value of the sample is greater than 30% at 3K and about 8% at 300K.

Claims (4)

1. the preparation method of a large magnetic resistance effect Fe-Ti-O noncrystalline membrane is characterized in that: adopt the preparation of ultrahigh vacuum(HHV) three target codeposition magnetron sputtering coaters, this step is following:

1) a Ti target and Fe target are installed respectively on the target head of coating equipment;

2) with behind the glass basic surface contaminant removal, install on the substrate frame, substrate up, target below, the distance of substrate and target is 13 cm;

3) unlatching magnetron sputtering equipment successively starts the one-level mechanical pump and the secondary molecular pump vacuumizes, and vacuum tightness is greater than 8.5 * 10 at the bottom of the back of the body of sputtering chamber ^{– 6}Pa;

4) feed O to Vakuumkammer ₂With the mixed gas of Ar, make that the vacuum tightness in the Vakuumkammer is 1 Pa;

5) open the sputter direct supply, on Ti target Fe target, apply electric current and voltage respectively, sputter is 20 minutes in advance, waits sputtering current and voltage stable;

6) open the baffle plate of substrate, the speed of changeing with PM 2 is simultaneously rotated substrate frame, the titania-doped noncrystalline membrane of growth iron on substrate;

7) growing film was closed the baffle plate of substrate after 15 minutes, and substrate frame stops operating, and closed shielding power supply then, stopped to feed sputter gas Ar and O ₂, close vacuum system after continuing to vacuumize half a hour, charging into purity to Vakuumkammer then is 99.999% nitrogen, presses when identical up to the air pressure and the outside atmosphere of Vakuumkammer, opens Vakuumkammer and takes out the target product that makes.

2. according to the preparation method of the said large magnetic resistance effect Fe-Ti-O of claim 1 noncrystalline membrane; It is characterized in that: the purity of said Ti target and Fe target is 99.99%; The thickness of Ti target is 4 mm, and the thickness of Fe target is 2.5 mm, and the diameter of Ti target and Fe target is 60 mm.

3. according to the preparation method of the said large magnetic resistance effect Fe-Ti-O of claim 1 noncrystalline membrane, it is characterized in that: said O ₂In the Ar mixed gas, O ₂Be 99.999% with the purity of Ar, wherein O ₂Flow be 3sccm, the flow of Ar is 100 sccm.

4. according to the preparation method of the said large magnetic resistance effect Fe-Ti-O of claim 1 noncrystalline membrane; It is characterized in that: said sputter direct supply applies the electric current of 0.4 A and the voltage of 340 V on the Ti target, on the Fe target, applies the electric current of 0.3 A and the voltage of 320 V.

Images