CN106711192B - A kind of p-type CuMSnO amorphous oxide semiconductor film and preparation method thereof - Google Patents

Abstract

The invention discloses a p-type CuMSnO amorphous oxide semiconductor thin film, wherein M is group III elements B, Al, Ga, In, Sc, Y. Among them: Cu and Sn are used together as the matrix elements of the material, Cu is +1 valence, Sn is +2 valence, and the two are combined with O to form the p-type conductivity of the material; M is +3 valence, which has a lower standard potential, It has high binding energy with O, and acts as a control element of hole concentration in the matrix; at the same time, Sn has a spherical electron orbit, and the electron cloud can also be highly overlapped in the amorphous state, so Sn also acts as a hole transport channel. . The invention also discloses a preparation method of the p-type CuAlSnO amorphous oxide semiconductor thin film and its application in thin film transistors. The hole concentration of the prepared film is 10 ¹⁴ ~10 ¹⁵ cm ^‑3 , and the visible light transmittance is ≧80%. The on-off current ratio of the TFT made of p-type CuAlSnO amorphous film as the channel layer is (1~9)×10 ⁴ , and the field effect mobility is 0.4~5cm ² /Vs.

Description

A kind of p-type CuMSnO amorphous oxide semiconductor film and preparation method thereof

technical field

The invention relates to an amorphous oxide semiconductor thin film, in particular to a p-type amorphous oxide semiconductor thin film and a preparation method thereof.

Background technique

Thin film transistor (TFT) is one of the core technologies in the field of microelectronics, especially display engineering. At present, TFT is mainly based on amorphous silicon (a-Si) technology, but a-Si TFT is opaque, has strong photosensitivity, and needs to add a mask layer. The pixel aperture ratio of the display screen is low, which limits the display performance. Moreover, the mobility of a-Si is low (~2 cm ² /Vs), which cannot meet the requirements of some applications. Although TFT based on polysilicon (p-Si) technology has high mobility, its device uniformity is poor and its fabrication cost is high, which limits its application. In addition, organic semiconductor thin-film transistors (OTFTs) have also been studied a lot, but OTFTs have low stability and relatively low mobility (~1 cm ² /Vs), which is a big constraint for their practical applications.

In order to solve the above problems, people have started to devote themselves to the research of amorphous oxide semiconductor (AOS) TFT in recent years, the most representative of which is InGaZnO. Different from Si-based TFTs, AOS TFTs have the following advantages: visible light transparency, low photosensitive degradation, no need to add a mask layer, increased aperture ratio, which can solve the limitation of low aperture ratio on high-resolution and ultra-fine display screens; easy to use at room temperature Deposition, suitable for organic flexible substrates; high mobility, high on/off current ratio, fast device response speed, applied to high drive current and high-speed devices; small characteristic unevenness, and time variation of current It is small and suppresses display unevenness of the panel, making it suitable for large-area applications.

Due to the special electronic structure of metal oxides, the 2p energy level of oxygen atoms is generally much lower than the valence band electron energy level of metal atoms, which is not conducive to orbital hybridization. Therefore, the valence band top formed by O 2p orbitals is very deep and localized. Therefore, the vast majority of oxides are inherently n-type conductive, and there are only a handful of oxides with p-type conductive characteristics. The currently reported p-type conductive oxide semiconductors are mainly SnO, NiO, Cu ₂ O, CuAlO ₂ and so on, but these oxides are all crystalline structures, not amorphous. The AOS that people are studying at present, such as InGaZnO, etc. are all n-type semiconductors, and there are almost no amorphous oxide semiconductors with p-type conductivity. Therefore, the currently reported AOS TFTs are all n-channel and lack p-channel AOS TFTs, which greatly restricts the application of AOS TFTs in new generation displays, transparent electronics and many other fields. Therefore, designing, finding and preparing p-type conductive amorphous oxide semiconductor thin films is a difficult problem that people need to solve urgently.

Contents of the invention

Aiming at practical application requirements, the present invention intends to provide a p-type amorphous oxide semiconductor thin film and a preparation method thereof.

The invention provides a p-type CuMSnO amorphous oxide semiconductor thin film, wherein M is group III elements B, Al, Ga, In, Sc, Y. Among them: Cu and Sn are used together as the matrix elements of the material, Cu is +1 valence, Sn is +2 valence, and the two are combined with O to form the p-type conductivity of the material; M is +3 valence, which has a lower standard potential, It has high binding energy with O, and acts as a control element of hole concentration in the matrix; at the same time, Sn has a spherical electron orbit, and the electron cloud is highly overlapped in the amorphous state, so Sn also acts as a hole transport channel.

In the p-type CuMSnO amorphous oxide semiconductor thin film provided by the present invention, in CuMSnO, Cu has a valence of +1, and M is one of group III elements B, Al, Ga, In, Sc, and Y, and is +3 valence, Sn is +2 valence; CuMSnO film is amorphous, its chemical formula is CuM _x Sn _y O _0.5+1.5x+y , where 0.5≦x≦1.5, 1≦y≦2; CuMSnO amorphous film has p-type Conductive properties.

The p-type CuMSnO amorphous oxide semiconductor film provided by the present invention, specifically, further, when M is Al, then CuMSnO is CuAlSnO, as in each embodiment, the hole concentration of the p-type CuAlSnO amorphous oxide semiconductor film is 10 ¹⁴ ~10 ¹⁵ cm ^-3 , visible light transmittance≧80%.

The present invention also provides a preparation method for preparing the p-type CuAlSnO amorphous oxide semiconductor thin film, the specific steps are as follows:

(1) Using high-purity Cu ₂ O, Al ₂ O ₃ and SnO powders as raw materials, mixing, grinding, and sintering in an Ar atmosphere at 950-1050 ° C to make CuAlSnO ceramic sheets as targets, in which Cu, Al, Sn The atomic ratio of the three components is 1:(0.5~1.5):(1~2);

(2) Using the pulsed laser deposition (PLD) method, the substrate and target are installed in the PLD reaction chamber, and the vacuum is lower than 1×10 ^-3 Pa;

(3) Introduce _O2 as the working gas, the gas pressure is 9~13Pa, and the substrate temperature is room temperature. The target is bombarded with pulsed laser, and the atoms and molecules on the surface of the target are melted and evaporated and deposited on the substrate to form a thin film. A p-type CuAlSnO amorphous film is obtained.

Using the p-type CuAlSnO amorphous oxide semiconductor thin film of the present invention as the channel layer, an AOS thin film transistor (TFT) is prepared, and the switching current ratio of the obtained p-type amorphous CuAlSnO TFT is (1~9)×10 ⁴ . The mobility is 0.4~5cm ² /Vs.

The above-mentioned material parameters and process parameters are established by the inventor through many experiments and need to be strictly controlled. If the inventor’s experiment exceeds the range of the above-mentioned parameters, the p-type CuAlSnO material cannot be realized, nor can it be obtained. Amorphous CuAlSnO thin film.

In the p-type CuMSnO system, when M is B, Ga, In, Sc or Y, it has the same mechanism as M is Al, and thus has similar properties. Other p-type CuMSnO amorphous oxides except CuAlSnO Thin films of material semiconductors can be prepared by the above-mentioned similar methods and steps, and the obtained materials and devices can have similar properties.

The beneficial effects of the present invention are:

1) The p-type CuMSnO amorphous oxide semiconductor thin film according to the present invention, wherein Cu and Sn are used as the matrix elements of the material, and the two are combined with O to form the p-type conductivity of the material, M is a group III element, and in the matrix As the control element of hole concentration, and Sn plays the role of hole transport channel, based on the above principles, CuMSnO is an ideal p-type AOS material.

2) The p-type CuMSnO amorphous oxide semiconductor thin film described in the present invention has good material properties, and its p-type conductivity can be easily regulated by the composition ratio.

3) The p-type CuMSnO amorphous oxide semiconductor thin film described in the present invention is used as the channel layer to prepare the p-type AOS TFT with good performance, which lays the foundation for the application of the p-type AOS TFT.

4) The p-type CuMSnO amorphous oxide semiconductor thin film described in the present invention, combined with the existing n-type InGaZnO amorphous oxide semiconductor thin film, can form a complete p-n system of AOS, and p-type CuMSnO and n-type InGaZnO Both are transparent semiconductor materials, so transparent optoelectronic devices and transparent logic circuits can be produced, creating the application of AOS in transparent electronic products, and greatly promoting the development of transparent electronics.

5) The p-type CuMSnO amorphous oxide semiconductor thin film described in the present invention grows completely at room temperature, and is very suitable for organic flexible substrates, so it can be widely used in wearable and intelligent flexible products.

6) The p-type CuMSnO amorphous oxide semiconductor thin film of the present invention has a wide parameter window during the growth process, is easy to deposit in a large area at room temperature, has low energy consumption, simple preparation process and low cost, and can realize industrial production.

Description of drawings

FIG. 1 is a schematic diagram of the structure of a p-type amorphous CuAlSnO TFT device used in each embodiment. In the figure, 1 is the low-resistance n ⁺⁺ Si substrate, which also serves as the gate, 2 is the _SiO2 insulating dielectric layer, 3 is the p-type amorphous CuAlSnO channel layer, 4 is the metal Ni source, and 5 is the metal Ni drain.

FIG. 2 is the output characteristic curve of the TFT with the p-type CuAlSnO amorphous oxide semiconductor thin film as the channel layer prepared in Example 1. FIG.

FIG. 3 is a transfer characteristic curve of a TFT with a p-type CuAlSnO amorphous oxide semiconductor thin film as a channel layer prepared in Example 1. FIG.

specific embodiment

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

(1) Using high-purity Cu ₂ O, Al ₂ O ₃ and SnO powders as raw materials, mixing, grinding, and sintering in an Ar atmosphere at 950 ° C to make CuAlSnO ceramic sheets as targets, in which Cu, Al, and Sn are three groups The atomic ratio of minutes is 1:0.5:2;

(2) Using the pulsed laser deposition (PLD) method, install the substrate and target in the PLD reaction chamber, and evacuate to 9×10 ^-4 Pa;

(3) Introduce _O2 as the working gas, the gas pressure is 13Pa, and the substrate temperature is room temperature. The target is bombarded with a pulsed laser. p-type CuAl _0.5 Sn ₂ O _3.25 amorphous film.

Using quartz as the substrate, the p-type CuAl _0.5 Sn ₂ O _3.25 thin film was prepared according to the above growth steps, and its structure, electrical and optical properties were tested. The test results are: the thin film is amorphous, with a thickness of 32nm; it has p-type conductivity Characteristics, hole concentration 10 ¹⁴ cm ^-3 ; visible light transmittance 82%.

Using n ⁺⁺ -Si coated with SiO ₂ with a thickness of 300nm as the substrate, a p-type CuAl _0.5 Sn ₂ O _3.25 thin film was prepared according to the above growth steps, which was used as the channel layer, and the structure shown in Figure 1 was used to produce TFT device, n ⁺⁺ -Si is the gate, 300nm thick SiO ₂ is the gate insulating layer, CuAl _0.5 Sn ₂ O _3.25 channel layer is 32nm thick, 100nm thick Ni metal is the source and drain, TFT channel The layer length and width were 200 μm and 1000 μm, respectively. The device performance test of the TFT with the p-type CuAlSnO amorphous film as the channel layer is carried out. Figure 2 is the output characteristic curve obtained from the test, and Figure 3 is the transfer characteristic curve obtained from the test. The on-off current ratio is 1×10 ⁴ , and the field effect The mobility is 0.4cm ² /Vs.

Example 2

(1) Using high-purity Cu ₂ O, Al ₂ O ₃ and SnO powders as raw materials, mixing, grinding, and sintering in an Ar atmosphere at 1000 ° C to make CuAlSnO ceramic sheets as targets, in which Cu, Al, and Sn are three groups The atomic ratio of the fraction is 1:1:1;

(2) Using the pulsed laser deposition (PLD) method, install the substrate and target in the PLD reaction chamber, and evacuate to 9×10 ^-4 Pa;

(3) Introduce _O2 as the working gas, the gas pressure is 11Pa, and the substrate temperature is room temperature. The target is bombarded with a pulsed laser, and the atoms and molecules on the surface of the target are melted and evaporated and deposited on the substrate to form a thin film. p-type _CuAlSnO3 amorphous film.

Using quartz as the substrate, the p-type CuAlSnO ₃ thin film was prepared according to the above growth steps, and its structure, electrical and optical properties were tested. The test results are: the thin film is amorphous, with a thickness of 35nm; it has p-type conductivity, and the hole Concentration 10 ¹⁴ cm ^-3 ; visible light transmittance 85%.

Using n ⁺⁺ -Si coated with SiO ₂ with a thickness of 300nm as the substrate, a p-type CuAlSnO ₃ thin film was prepared according to the above growth steps, which was used as the channel layer, and a TFT device was fabricated using the structure shown in Figure 1, n ⁺⁺ -Si is the gate, 300nm thick SiO ₂ is the gate insulating layer, CuAlSnO ₃ channel layer is 35nm thick, 100nm thick Ni metal is the source and drain, and the length and width of the TFT channel layer are 200μm and 1000μm. Device performance test was carried out on the TFT with the p-type CuAlSnO amorphous film as the channel layer. The test results showed that the on-off current ratio was 9×10 ⁴ , and the field-effect mobility was 5 cm ² /Vs.

Example 3

(1) Using high-purity Cu ₂ O, Al ₂ O ₃ and SnO powders as raw materials, mixing, grinding, and sintering in an Ar atmosphere at 1050 ° C to make CuAlSnO ceramic sheets as targets, in which Cu, Al, and Sn are three groups The atomic ratio of points is 1:1.5:2;

(2) Using the pulsed laser deposition (PLD) method, install the substrate and target in the PLD reaction chamber, and evacuate to 9×10 ^-4 Pa;

(3) Introduce _O2 as the working gas, the gas pressure is 9Pa, and the substrate temperature is room temperature. The target is bombarded with pulsed laser, and the atoms and molecules on the surface of the target are melted and evaporated and deposited on the substrate to form a thin film. p-type CuAl _1.5 Sn ₂ O _4.75 amorphous film.

Using quartz as the substrate, the p-type CuAl _1.5 Sn ₂ O _4.75 film was prepared according to the above growth steps, and its structure, electrical and optical properties were tested. The test results were: the film was amorphous, with a thickness of 38nm; it had p-type conductivity Characteristics, hole concentration 10 ¹⁵ cm ^-3 ; visible light transmittance 81%.

Using n ⁺⁺ -Si coated with SiO ₂ with a thickness of 300nm as the substrate, a p-type CuAl _1.5 Sn ₂ O _4.75 thin film was prepared according to the above growth steps, which was used as the channel layer, and the structure shown in Figure 1 was used to produce TFT device, n ⁺⁺ -Si is the gate, 300nm thick SiO ₂ is the gate insulating layer, CuAl _1.5 Sn ₂ O _4.75 channel layer is 38nm thick, 100nm thick Ni metal is the source and drain, TFT channel The layer length and width were 200 μm and 1000 μm, respectively. The device performance test of the TFT with the p-type CuAlSnO amorphous film as the channel layer was carried out, and the test results showed that the on-off current ratio was 7×10 ⁴ , and the field-effect mobility was 2 cm ² /Vs.

In the above-mentioned embodiments, the purity of the raw materials Cu ₂ O powder, Al ₂ O ₃ powder and SnO powder used are all above 99.99%.

The substrate used in the preparation of the p-type CuAlSnO amorphous oxide semiconductor thin film of the present invention is not limited to the single crystal silicon wafer and quartz wafer in the embodiment, and various other types of substrates can be used.

In the p-type CuMSnO system, M is group III elements B, Al, Ga, In, Sc, Y. The above-mentioned embodiments are specifically illustrated by the preparation of a P-type CuAlSnO amorphous oxide semiconductor film in which M is Al. For M being B, Ga, In, Sc or Y, the same mechanism as M being Al has the same mechanism, and the corresponding CuMSnO The materials also have similar properties, and other p-type CuMSnO amorphous oxide semiconductor films other than CuAlSnO can also be prepared by the above-mentioned similar method and steps, and the obtained materials and devices have similar properties.

Claims (6)

1. A p-type CuMSnO amorphous oxide semiconductor thin film, characterized in that: the M element in the CuMSnO is any one of Group III elements B, Al, Ga, In, Sc, Y, and M is +3 The valence is used as the control element of the hole concentration in the matrix; Cu and Sn are used as the matrix element of the material together, Cu is +1 valence, Sn is +2 valence, and the combination of the two and O forms the p-type conductivity of the material; and Sn It has a spherical electron orbit, and the electron cloud is highly overlapped in the amorphous state, which acts as a hole transport channel. 2. A p-type CuMSnO amorphous oxide semiconductor film according to claim 1, characterized in that: the chemical formula of the p-type CuMSnO amorphous oxide semiconductor film is CuM _x Sn _y O _0.5+1.5x+y , where 0.5≦x≦1.5, 1≦y≦2. 3. a kind of p-type CuMSnO amorphous oxide semiconductor film according to claim 2, it is characterized in that: M is Al, and described CuMSnO is CuAlSnO, and the hole concentration of p-type CuAlSnO amorphous oxide semiconductor film is 10 ¹⁴ ~10 ¹⁵ cm ^-3 . 4. the preparation method of p-type CuMSnO amorphous oxide semiconductor film as claimed in claim 3, is characterized in that: the step of preparing described p-type CuAlSnO amorphous oxide semiconductor film comprises: 1) Using high-purity Cu ₂ O, Al ₂ O ₃ and SnO powders as raw materials, mixing, grinding, and sintering in an Ar atmosphere at 950-1050 ° C to make CuAlSnO ceramic sheets as targets, in which Cu, Al, Sn three The atomic ratio of the components is 1:0.5~1.5:1~2; 2) Using the pulsed laser deposition method, install the substrate and target in the PLD reaction chamber, and evacuate to less than 1×10 ^-3 Pa; 3) Introduce _O2 as the working gas, the gas pressure is 9~13Pa, and the substrate temperature is room temperature. The target is bombarded with pulsed laser, and the atoms and molecules on the surface of the target are melted and deposited on the substrate to form a thin film. A p-type CuAlSnO amorphous film is obtained. 5. The application of the p-type CuMSnO amorphous oxide semiconductor thin film according to any one of claims 1 to 3, characterized in that: the p-type CuMSnO amorphous oxide semiconductor thin film is used as a p-type channel layer to prepare thin film transistor. 6. The application of the p-type CuMSnO amorphous oxide semiconductor thin film according to claim 5, characterized in that: the switching current ratio of the thin film transistor is 1×10 ⁴ to 9×10 ⁴ , and the field effect mobility is 0.4~ 5cm ² /Vs.