Metal oxide semiconductor material, target material and method for preparing the same, thin film transistor and method for preparing the same

Abstract

The present disclosure relates to the technical field of semiconductor, and particularly relates to a metal oxide semiconductor material, a target material and a preparation method thereof, a thin film transistor and a preparation method thereof. Aiming at solving the problem of threshold voltage negative drift of metal oxide semiconductor TFT under NBIS in the related art, which causes the degradation of display picture. A metal oxide semiconductor material comprises: a semiconductor matrix material; and at least one rare earth compound doped in the semiconductor matrix material, each rare earth compound is represented by a general formula (M FD ) a A b ; in the general formula (M FD ) a A b , M FD is selected from one of the elements in the rare earth elements and the elements capable of f-d transition and / or charge transfer transition, A is selected from the elements capable of red shifting the wavelength band of the absorption spectrum of the corresponding M FD to the visible light wavelength band range, a is the atomic number of the element M FD ) a ) b in the general formula (M FD ), and b is the atomic number of the element A.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a metal oxide semiconductor material, a target material and a preparation method thereof, a thin film transistor and a preparation method thereof. Background Art

[0002] Thin Film Transistor (TFT) is a semiconductor device commonly used in flat panel displays. As a device for controlling and driving pixels in flat panel displays, it affects the development of flat panel displays. Summary of the Invention

[0003] The main purpose of the present invention is to provide a metal oxide semiconductor material, a target material, a preparation method thereof, a thin film transistor, and a preparation method thereof, to solve the problem in the related art that the threshold voltage of metal oxide semiconductor TFTs under NBIS negatively drifts, causing display degradation.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] In one aspect, a metal oxide semiconductor material is provided, comprising: a semiconductor matrix material; and at least one rare earth compound doped in the semiconductor matrix material, wherein the general formula of each rare earth compound is represented by (M FD ) a A b ; In the general formula (M FD ) a A b In, M FD Selected from rare earth elements, one of the elements capable of fd transition and / or charge transfer transition, A is selected from the element capable of making the corresponding M FD Elements with absorption spectra that undergo fd transition and / or charge transfer transition and whose wavelength bands are red-shifted to the visible light band, a is a general formula (M FD ) a A b Element M FD is the number of atoms of element A, and b is the number of atoms of element A.

[0006] In some embodiments, in the general formula (M FD ) a A b In, M FD One selected from the remaining elements in the lanthanide series except lanthanum.

[0007] In some embodiments, in the general formula (M FD ) a A b In, M FD One selected from the group consisting of cerium, praseodymium, neodymium, promethium, samarium, terbium and dysprosium.

[0008] In some embodiments, in the general formula (M FD ) a A b , M FD is selected from one of praseodymium and terbium.

[0009] In some embodiments, in the general formula (M FD ) a A b , A is selected from one of the elements having an electronegativity less than oxygen.

[0010] In some embodiments, in the general formula (M FD ) a A b , A is selected from one of sulfur, selenium, tellurium, bromine, iodine, arsenic and boron.

[0011] In some embodiments, in each rare earth compound included in the metal oxide semiconductor material, M FD requires a minimum energy less than 2.64 eV for f-d transition and / or charge transfer transition.

[0012] In some embodiments, in each rare earth compound included in the metal oxide semiconductor material, M FD requires a minimum energy greater than 2.48 eV for f-d transition and / or charge transfer transition.

[0013] In some embodiments, the semiconductor matrix material includes at least one first metal oxide and / or at least one second metal oxide, the general formula of each first metal oxide and each second metal oxide is represented as M c O d ; in each first metal oxide, M in the general formula M c O d is selected from one of the elements of indium, zinc, gallium, tin and cadmium; in each second metal oxide, M in the general formula M c O d is selected from a combination of two or more of the elements of indium, zinc, gallium, tin and cadmium; c is the number of M in the general formula M c O d and d is the number of atoms of the element oxygen in the general formula.

[0014] In some embodiments, in the general formula M c O d , M further includes one or a combination of two or more of the lanthanide metals, scandium and yttrium.

[0015] In some embodiments, in the metal oxide semiconductor material, the elemental composition of the semiconductor matrix material and the at least one rare earth compound is represented as ((M FD ) a A b ) X (M c O d ) 1-X ; wherein x is greater than or equal to 0.001 and less than or equal to 0.15.

[0016] In some embodiments, in the metal oxide semiconductor material of general formula (M FD ) a A b , when M FD is selected from one of praseodymium and terbium, x is greater than or equal to 0.01 and less than or equal to 0.1.

[0017] In some embodiments, in the metal oxide semiconductor material of general formula (M FD ) a A b , when M FD is selected from cerium, x is greater than or equal to 0.001 and less than or equal to 0.02.

[0018] In another aspect, there is provided a target material comprising the metal oxide semiconductor material as described above.

[0019] In some embodiments, in the metal oxide semiconductor material of general formula (M FD ) a A b , A is selected from one of sulfur, selenium, tellurium, arsenic and boron.

[0020] In another aspect, there is provided a thin film transistor comprising: an active layer, the material of the active layer comprising the metal oxide semiconductor material as described above.

[0021] In another aspect, there is provided a method for preparing a target material, comprising:

[0022] doping at least one rare earth compound into a semiconductor matrix material in proportion, and mixing uniformly; each rare earth compound is represented by a general formula (M FD ) a A b , in the general formula (M FD ) a A b , M FD is selected from one of rare earth elements, elements capable of f-d transition and / or charge transfer transition, A is selected from elements capable of red-shifting the wavelength band of the absorption spectrum of the corresponding M FD to the visible light wavelength band range, and a is the general formula (MFD ) a A b Element M FD is the number of atoms of element A, and b is the number of atoms of element A.

[0023] The semiconductor matrix material doped with the at least one rare earth compound after uniform mixing is subjected to ball milling, hot pressing or slurry casting, and sintering to obtain the target material.

[0024] In some embodiments, in the general formula (M FD ) a A b wherein A is selected from one of sulfur, selenium, tellurium, arsenic and boron.

[0025] In another aspect, a method for preparing a thin film transistor is provided, comprising:

[0026] A semiconductor thin film is formed on a substrate. The material of the semiconductor thin film includes a semiconductor matrix material and at least one rare earth compound doped in the semiconductor matrix material. The general formula of each rare earth compound is expressed as (M FD ) a A b , in the general formula (M FD ) a A b In, M FD Selected from rare earth elements, one of the elements capable of fd transition and / or charge transfer transition, A is selected from the element capable of making the corresponding M FD Elements with absorption spectra that undergo fd transition and / or charge transfer transition and whose wavelength bands are red-shifted to the visible light band, a is a general formula (M FD ) a A b Element M FD The number of atoms of element A is , and b is the number of atoms of element A; the semiconductor thin film is patterned to obtain the active layer of the thin film transistor.

[0027] In some embodiments, in the at least one rare earth compound, when A is selected from one or more of sulfur, selenium, tellurium, arsenic, and boron, forming a semiconductor thin film on a substrate includes:

[0028] A target material containing the metal oxide semiconductor material is provided; and the semiconductor film is formed on the substrate by a sputtering process.

[0029] Alternatively, target materials respectively containing the at least one rare earth compound and the semiconductor matrix material are provided; and the semiconductor thin film is formed on the substrate by a dual-target sputtering process.

[0030] In some embodiments, in the at least one rare earth compound, in the case where A is selected from one of bromine and iodine, the forming a semiconductor thin film on a substrate includes forming the semiconductor thin film on the substrate by a solution method.

[0031] In some embodiments, the solution method includes one of spin coating, inkjet printing, screen printing, blade coating, and imprinting.

[0032] Embodiments of the present application provide a metal oxide semiconductor material, a target material and a preparation method thereof, and a thin film transistor and a preparation method thereof. By selecting an anion environment, the rare earth element M FD absorbs blue light. Since the d-electron in the ion of the element has a short lifetime and a strong temperature quenching effect, the absorbed blue light is converted into a non-radiative form, thereby avoiding the problem of the threshold voltage negative drift caused by the ionization of oxygen vacancies by blue light in a backlight or self-luminous. Meanwhile, the cerium, praseodymium and terbium in the rare earth element can undergo a charge transfer transition, and by selecting an anion environment, the energy required for the charge transfer transition of the cerium, praseodymium and terbium in the rare earth element can be adjusted by changing the electron affinity of the anion, i.e., changing the reducing ability of the anion, so that M FD absorbs blue light. In addition, by studying the light stability of the metal oxide semiconductor TFT, it is found that the rare earth compounds are similar to one or a combination of more than two of lanthanide metals, scandium and yttrium, and the addition of these rare earth elements can also inhibit oxygen vacancies, reduce the oxygen vacancy concentration in the channel and at the interface, and improve the light stability of the metal oxide semiconductor TFT. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the present disclosure, the following will briefly introduce the drawings needed to be used in some embodiments of the present disclosure. Obviously, the drawings described in the following description are only the drawings of some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not limited to the actual size, actual process, actual time sequence, etc. of the product involved in the embodiments of the present disclosure.

[0034] Figure 1 is a sectional view of a thin film transistor according to some embodiments;

[0035] Figure 2 is a pixel circuit diagram of an AMOLED according to some embodiments;

[0036] Figure 3is a diagram of energy band structures under PBIS and NBIS based on the photogenerated hole-electron pair theory according to some embodiments;

[0037] Figure 4 is a flow chart of a method for preparing a target material according to some embodiments;

[0038] Figure 5 is a flow chart of a method for manufacturing a thin film transistor according to some embodiments;

[0039] Figure 6 is a transfer characteristic curve of a Pr2S3-doped thin film transistor under NBIS conditions according to some embodiments;

[0040] Figure 7 is a transfer characteristic curve of a Pr2O3-doped thin film transistor under NBIS conditions according to some embodiments;

[0041] Figure 8 Graphs showing absorption spectra of Pr2O3 and Pr2S3 doped semiconductor films according to some embodiments. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the embodiments described are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0043] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to indicate that the particular features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0044] Hereinafter, the terms "first", "second", etc. are used only for the purpose of description and do not constitute a relative importance or imply a specific number of the technical features indicated. Thus, the features defined with "first", "second" can include one or more of the features explicitly or implicitly. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is two or more, unless otherwise stated.

[0045] "A, B, and C at least one of" has the same meaning as "at least one of A, B, or C", and includes the following combinations of A, B, and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B, and C.

[0046] "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0047] The use of "adapted to" or "configured to" herein means open and inclusive language that does not exclude devices adapted to or configured to perform additional tasks or steps.

[0048] In addition, the use of "based on" means open and inclusive, as a process, step, calculation, or other action that is "based on" one or more stated conditions or values can in practice be based on additional conditions or values beyond those stated.

[0049] Exemplary embodiments are described herein with reference to cross-sectional and / or plan view illustrations that are idealized examples. In the interest of clarity, not all of the layers of regions that can be present in the figures are shown in the cross-sectional and / or plan views. Thus, the thickness of the layers and regions can be exaggerated for clarity. It will also be appreciated that changes in the thickness of layers and regions can occur when passing through the plane of the drawing. Thus, the exemplary embodiments should not be construed as limited to the shapes of regions illustrated in the figures, which are schematic, but include shapes that can, for example, result from manufacturing. For example, etched regions will typically have a curved shape rather than a rectangular shape as illustrated in the figures. It is to be understood that the regions illustrated in the figures are schematic and that their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the exemplary embodiments.

[0050] Some embodiments of the present disclosure provide a display device, comprising a display panel, and a driving circuit, such as a pixel driving circuit, a gate driving circuit, etc., disposed on the display panel.

[0051] A thin film transistor (TFT) is an important component for constituting a pixel driving circuit, a gate driving circuit, etc. In the process of energizing, by controlling the opening and closing of the thin film transistor, the pixel driving circuit and the gate driving circuit can be controlled to drive the display panel to display.

[0052] Among them, the display device mentioned above can be one of LCD (Liquid Crystal Display), OLED (Organic Light-Emitting Diode), QLED (Quantum Dot Light Emitting Diodes), MicroLED (Micro Light Emitting Diodes), miniLED (mini Light Emitting Diodes) display devices, etc.

[0053] The display device may specifically be a mobile phone, a tablet computer, a notebook, a personal digital assistant (PDA), a car computer, a laptop computer, a digital camera, etc.

[0054] Depending on the material of the active layer, thin film transistors (TFTs) mainly include amorphous silicon (such as hydrogenated amorphous silicon: a-Si:H) TFTs, low temperature polysilicon (LTPS) TFTs, metal oxide TFTs, and organic TFTs.

[0055] Among them, metal oxide semiconductor TFTs have received more attention due to the advantages of metal oxides such as large band gap, high carrier mobility, low process temperature, and good device uniformity. At the same time, metal oxide semiconductor TFTs also have some problems to be solved. For example, metal oxide semiconductors are usually n-type conductive and it is difficult to obtain p-type conductive characteristics, so their application in complementary circuits is limited. In addition, the negative gate voltage stress stability of metal oxide semiconductors under light is still insufficient. Especially for thin film transistors 1 as display panel components, they will inevitably be exposed to light in applications in the display field. For example, Figure 1 As shown, in a liquid crystal display, the channel 121 of the thin film transistor 1 is exposed to backlight, while in an OLED display, the channel 121 of the thin film transistor 1 is affected by the self-luminescence of the OLED. Whether it is a backlight or self-luminescence, the light emitted is in the visible light range, and the blue light has the highest photon energy. Metal oxide semiconductor materials (such as IZO (Indium Zinc Oxide) and IGZO (Indium Gallium Zinc Oxide)) are particularly sensitive to blue light because blue light ionizes oxygen vacancies in the metal oxide semiconductor material and releases electrons into the conduction band to participate in electrical conduction, thereby causing the threshold voltage to shift negatively and causing display image degradation.

[0056] Here, as shown in Figure 2 , in the driving of AMOLED (Active-matrix organic light emitting diode) display pixels, at least two TFTs are included, respectively referred to as addressing pipe TFT1 and driving pipe TFT2. Since metal oxide semiconductor TFTs mostly only show n-channel characteristics, they are in an open state under positive gate voltage and in a closed state under negative gate voltage (when the metal oxide semiconductor carrier concentration is large, a normally open state occurs, i.e. a negative gate voltage is needed to completely turn it off). The addressing pipe TFT1 is only turned on once in each scanning period, and is in a closed state for the rest of the time, so the stability of the addressing pipe TFT1 under negative gate bias stress (NBS) is extremely important. The source of the driving pipe TFT2 is directly connected to the OLED, and as long as the OLED emits light, a certain size of current will flow through the source-drain electrode of the driving pipe TFT2, so the driving pipe TFT2 is basically in an open state, and its stability under positive gate voltage stress (PBS) is relatively important. The metal oxide semiconductor TFT will show threshold voltage (V th ) drift phenomenon under gate voltage stress.

[0057] In the following, the conditions causing threshold voltage drift will be described in detail. As shown in Figure 3 , taking the capture model of photo-generated holes as a starting point, under the action of light, photo-generated electron-hole pairs will be generated in the metal oxide semiconductor layer (i.e. active layer 12). As shown in Figure 3 (a), if the gate 13 is simultaneously applied with PBS, a large number of electrons will be generated at the interface between the active layer 12 and the gate insulating layer 14, shielding the electric field, thereby weakening the induced electric field on the active layer 12, so that the photo-generated electron-hole pairs will not move. When the stress is removed, the electrons will immediately recombine, so the threshold voltage drift phenomenon of the TFT under the PBIS (Positive gate bias illumination stress) condition is not obvious. As shown in Figure 3 (b), if the gate 13 is simultaneously applied with NBS, since the metal oxide semiconductor is n-type conductive, when the gate 13 is applied with negative gate voltage, the active layer 12 is in a depletion state, at this time, a voltage drop will occur between the upper and lower surfaces of the active layer 12, causing holes to move to the interface between the active layer 12 and the gate insulating layer 14, and electrons to move in the opposite direction. The holes moving to the interface between the active layer 12 and the gate insulating layer 14 will be captured or will enter the gate insulating layer 14, so that when the stress is removed, the electrons cannot recombine with the holes, thereby causing negative threshold voltage drift.

[0058] Therefore, it is particularly important to improve the threshold voltage stability of the metal oxide semiconductor TFT under NBIS (Negative gate bias illumination stress).

[0059] To solve the above problems, in the related art, the active layer 12 of the thin film transistor 1 is subjected to light shielding treatment to improve the light stability by increasing the black matrix. However, this method cannot solve the problem of light entering the oxide semiconductor layer through diffraction, and the improvement of stability under long-time light conditions is limited. Moreover, by increasing the light shielding process, the complexity of preparation is increased, resulting in an increase in manufacturing cost.

[0060] Based on this, in some embodiments, the metal oxide semiconductor material includes a semiconductor matrix material, and at least one rare earth compound doped in the semiconductor matrix material, each rare earth compound is represented by a general formula (M FD ) a A b In the general formula (M FD ) a A b , M FD is selected from one of the rare earth elements, elements capable of f-d transition and / or charge transfer transition, A is selected from elements capable of red-shifting the wavelength band of the absorption spectrum of the corresponding M FD f-d transition and / or charge transfer transition to the visible light wavelength band, a is the atomic number of the element M FD ) a A b in the general formula (M FD ), and b is the atomic number of the element A.

[0061] The semiconductor matrix material can be a p-type metal oxide semiconductor material or an n-type metal oxide semiconductor material, which is not specifically limited herein. In the case of a p-type metal oxide semiconductor material, the p-type metal oxide semiconductor material can include copper oxide CuO, tin oxide SnO, etc. In the case of an n-type metal oxide semiconductor material, examples of the n-type metal oxide semiconductor material can include ITO (Indium Tin Oxide), IGZO (Indium Gallium Zinc Oxide), etc.

[0062] In some embodiments, the semiconductor matrix material can include at least one first metal oxide and / or at least one second metal oxide. Each first metal oxide and each second metal oxide is represented by a general formula (M c O dIn each of the first metal oxides, M in the general formula is selected from one of the elements of indium, zinc, gallium, tin, and cadmium, and in each of the second metal oxides, M in the general formula is selected from a combination of two or more of the elements of indium, zinc, gallium, tin, and cadmium, c is the number of M in the general formula, and d is the number of atoms of oxygen in the general formula.

[0063] In each of the first metal oxides, M in the general formula is selected from one of the elements of indium, zinc, gallium, tin, and cadmium, and in each of the second metal oxides, M in the general formula is selected from a combination of two or more of the elements of indium, zinc, gallium, tin, and cadmium, c is the number of M in the general formula, and d is the number of atoms of oxygen in the general formula.

[0064] In each of the first metal oxides, M in the general formula is selected from one of the elements of indium, zinc, gallium, tin, and cadmium, and in each of the second metal oxides, M in the general formula is selected from a combination of two or more of the elements of indium, zinc, gallium, tin, and cadmium, c is the number of M in the general formula, and d is the number of atoms of oxygen in the general formula.

[0065] However, it should be noted that in actual applications, considering the presence of vacancies, gaps, and other defects in the thin film, at this time, c and d can be decimal numbers. For example, taking In2O3 as an example, the ratio of the number of atoms of In to the number of atoms of O can slightly deviate from 2:3. Taking PrB6 as an example, the ratio of the number of atoms of Pr to the number of atoms of B can slightly deviate from 1:6. For semiconductor matrix materials containing only tin oxides, according to the tin oxides, which can include SnO and SnO2, it can be known that in the semiconductor matrix material, the ratio of the number of atoms of Sn to the number of atoms of O can be less than 1, such as 0.95, at this time, the tin oxide is SnO.

[0066] For M being selected from different combinations, the second metal oxide can be ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide) or IGZO (Indium Gallium Zinc Oxide), ITZO (Indium Tin Zinc Oxide), wherein ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide) belong to ternary oxides, IGZO (Indium Gallium Zinc Oxide), ITZO (Indium Tin Zinc Oxide) belong to quaternary oxides. For these oxides, c can be equal to 1, d can be equal to 1. Similarly, due to the existence of vacancies, interstitials and other defects in the metal oxide semiconductor thin film, at this time, c and d can also be decimal numbers.

[0067] According to the above, except for SnO, the rest of the metal oxides can be n-type metal oxide semiconductor materials, and the oxide SnO can only achieve p-type conduction under strict single crystal conditions, so in some embodiments, in the general formula, when M is selected from tin, c can be equal to 1, and d can be equal to 2. That is, the oxide of tin is SnO2, in this case, the metal oxide semiconductor material is an n-type metal oxide semiconductor material, and in an amorphous state, it has very high electron mobility. Here, similarly to the above-mentioned vacancies, interstitials and other defects in the metal oxide semiconductor thin film, c and d can also be decimal numbers.

[0068] Based on the above semiconductor matrix material, in the study of the light stability of metal oxide semiconductor TFT, it is found that the ionization of oxygen vacancies is the cause of persistent photoconductivity, and the photo-generated hole carriers are confined at the oxygen vacancies, and the oxygen vacancies become singly ionized Vo + or doubly ionized Vo 2+ , which in turn contributes to free electrons related to persistent photoconductivity, so by reducing the oxygen vacancy concentration in the channel and at the interface, it is expected to improve the light stability of the metal oxide semiconductor TFT. Therefore, in order to suppress oxygen vacancies, in some embodiments, in the general formula M c O d , M also includes one or a combination of any two or more of lanthanide metals, scandium and yttrium.

[0069] At this time, according to the above in the general formula M c O dIn the case where M is selected from one of indium, zinc, gallium, tin and cadmium, M also includes one or a combination of any two or more of lanthanide metals, scandium and yttrium. It can be seen that M can be selected from any two or more of indium, zinc, gallium, tin, cadmium, lanthanide metals, scandium and yttrium, that is, M c O d It is a polyvalent oxide.

[0070] For example, in this case, when M does not include one or a combination of any two or more of lanthanide metals, scandium and yttrium, M can be selected from indium. In this case, c can be equal to 2, d can be equal to 3, that is, M c O d In the case of In2O3. In the case where M includes one or a combination of any two or more of lanthanide metals, scandium and yttrium, M can be selected from the combination of indium and scandium. In this case, c can be equal to 1, d can be equal to 1, and M c O d It can be expressed as ScInO.

[0071] According to the above general formula M c O d In the case where M is selected from a combination of any two or more of indium, zinc, gallium, tin and cadmium, M also includes one or a combination of any two or more of lanthanide metals, scandium and yttrium. It can be seen that M can be selected from a combination of any three or more of indium, zinc, gallium, tin, cadmium, lanthanide metals, scandium and yttrium. In this case, M c O d It is also a polyvalent oxide.

[0072] For example, in this case, when M does not include one or a combination of any two or more of lanthanide metals, scandium and yttrium, M can be selected from indium and cadmium. In this case, c and d can both be equal to 1, that is, M c O d In the case of InCdO. When M includes one or a combination of any two or more of lanthanide metals, scandium and yttrium, M can be selected from the combination of indium, cadmium and scandium. In this case, c and d can also be equal to 1. In this case, M c O d It can be expressed as ScCdInO.

[0073] According to the general formula of each rare earth compound above, (M FD ) a A b , in the general formula (M FD ) a A b In, M FD Selected from rare earth elements, one of the elements capable of fd transition and / or charge transfer transition, A is selected from the element capable of making the corresponding MFD The element that causes the red shift of the absorption spectrum of the f-d transition and / or the charge transfer transition to the visible light band range, a is the atomic number of element MFD, and b is the atomic number of element A. It can be known that in the general formula (M FD ) a A b The atomic number of element MFD, b is the atomic number of element A. It can be known that in the general formula (M FD ) a A b , M FD may be selected from one of the remaining elements in the lanthanide series except for lanthanum. According to the wavelength range of visible light in the electromagnetic spectrum, it is approximately in the range of 880nm-380nm, and in the visible light band, the maximum photon energy is blue light emission, and the semiconductor matrix material (such as IZO (Indium Zinc Oxide), IGZO (Indium Gallium Zinc Oxide) and the like) is most sensitive to blue light. Therefore, although theoretically, ions containing f electrons and unfilled d energy level orbits (elements from cerium to platinum in the periodic table, that is, all elements from 58 to 78) can all occur f-d transition, but the energy (E fd ) required for f-d transition of free ions is greater than 6eV, and the absorption is in the deep ultraviolet region, which cannot absorb blue light, especially hafnium, tantalum and tungsten and other elements outside the lanthanide series, because the f electron is full, its E fd is extremely large, and no matter what method is used, it is impossible to make f-d transition absorption red shift to the blue light region. And the lanthanum element itself has no f electron, so it cannot occur f-d transition. For cerium, praseodymium and terbium in rare earth elements, similar to most organic matter, under the irradiation of electromagnetic waves, charge transfer transition occurs, that is, the electron jumps from the electron orbit of the ligand (here is the anion of A) to the electron orbit of the metal ion, producing charge transfer absorption spectrum, which can also absorb blue light. For example, the charge transfer absorption spectrum can be the spectrum absorbed by the oxidation of trivalent ions to tetravalent ions.

[0074] It should be noted that for the rare earth element selected from one of cerium, praseodymium and terbium, there can be overlap between the spectra absorbed by the f-d transition and the charge transfer transition of the ion of the rare earth element.

[0075] As shown in Table 1 below, the values of E fd of trivalent ions of some elements in the lanthanide series.

[0076] Table 1

[0077]

[0078] In some embodiments, in the general formula (M FD ) a Ab M FD is selected from one of cerium, praseodymium, neodymium, promethium, samarium, terbium and dysprosium. The ions of these elements have relatively low E fd , and by selecting the anion environment, M FD absorption of blue light can be more easily achieved. Since the d-electrons of the ions of these elements have short lifetimes and have a strong temperature quenching effect, the absorbed blue light can be converted into a non-radiative form, thereby avoiding the problem of threshold voltage negative drift caused by the ionization of oxygen vacancies by blue light in a backlight or self-luminous light, thereby avoiding the problem of threshold voltage negative drift caused by the ionization of oxygen vacancies by blue light in a backlight or self-luminous light. At the same time, since cerium, praseodymium and terbium among the above rare earth elements can undergo charge transfer transitions, and by selecting the anion environment, the energy required for the charge transfer transitions of cerium, praseodymium and terbium among the rare earth elements can be adjusted by changing the electron affinity of the anion, i.e. by changing the reducing power of the anion, and M FD absorption of blue light can also be achieved. In addition, by studying the light exposure stability of metal oxide semiconductor TFTs, it is found that the addition of these rare earth compounds, similar to the above M

[0079] According to the structural characteristics of the above thin film transistor 1, the metal oxide semiconductor material can be formed in the channel region of the active layer 12, or can be formed as a light shielding material in the region of the active layer 12 that needs to be light shielded. For example, in a liquid crystal display panel, in order to prevent the light emitted by the backlight from affecting the active layer 12, a light shielding layer including the metal oxide semiconductor material can be formed only on the surface of the active layer 12 close to the substrate 11, and the materials in the remaining positions of the active layer 12 can be selected from metal oxide semiconductor materials doped with (M FD ) a A b metal oxide semiconductor material.

[0080] Of course, the materials in all positions of the active layer 12 can be selected from metal oxide semiconductor materials doped with (M FD ) a A b metal oxide semiconductor material. At this time, according to different positions, metal oxide semiconductor materials of different doping types or metal oxide semiconductor materials of the same doping type but different doping amounts can be selected. Here, the application position and the doping proportion of the above metal oxide semiconductor material doped with (M FD ) a A b in the active layer 12 are not specifically limited.

[0081] In some embodiments, in the general formula (M FD ) a A b In, M FD One of praseodymium and terbium. The E of the ions of these two elements fd Compared to the E of neodymium, promethium, samarium, and dysprosium ions fd are high, and it is easier to achieve blue light absorption by setting up an anion environment. Although cerium has the lowest E fd However, cerium is very active and easily forms electron traps, which affects electron transport. FD In the case of cerium, (M FD ) a A b Doping is not conducive to improving the carrier mobility.

[0082] In some embodiments, in the general formula (M FD ) a A b In the formula (A), A is selected from one of the elements having less electronegativity than oxygen.

[0083] According to the large electronegativity of oxygen (about 3.44), M FD The oxide has strong ionicity, M FD The interaction between M and oxygen is weak, so FD The d orbital energy level of the oxide is less split by the crystal field, making M FD The ion E fd Still large, light absorption in the ultraviolet region. In these embodiments, by selecting an element with less electronegativity than oxygen, M FD The degree of covalency between M and A increases, so that FD The d orbital energy level of the ion will be greatly split due to the larger electron cloud expansion effect, thereby greatly reducing the energy level difference between the f configuration and the d configuration, and further greatly reducing E fd , which red-shifts the absorption of the ion's fd transition and achieves the absorption of blue light.

[0084] Among them, under the same test conditions, the electronegativity of oxygen, fluorine, chlorine, nitrogen, bromine, iodine, sulfur, selenium, tellurium, phosphorus, arsenic and boron is shown in Table 2 below.

[0085] Table 2

[0086]

[0087] As can be seen from Table 2, in the general formula (M FD ) a A b In the above, A can be selected from one of chlorine, nitrogen, bromine, iodine, sulfur, selenium, tellurium, phosphorus, arsenic and boron.

[0088] In some embodiments, in the general formula (M FD ) a A b In the general formula (M FD ), A can be selected from one of sulfur, selenium, tellurium, bromine, iodine, phosphorus, arsenic and boron. The electronegativity of these elements is all less than 0.5 of the electronegativity of oxygen, which can produce a large electron cloud expansion effect.

[0089] It should be noted that among the elements of sulfur, selenium, tellurium, bromine, iodine, phosphorus, arsenic and boron, the electronegativity of boron is the lowest, and the hexaboride of the rare earth compound is very stable, and the M FD ion exists in multiple valences, which is conducive to reducing the E FD of the M fd ion. Therefore, in the general formula (M FD ) a A b , A can be selected from boron.

[0090] The doping amount of the at least one rare earth compound described above is not specifically limited, and in actual applications, according to the f-d transition of the M FD ion in the above rare earth compound, which belongs to a transition allowed transition, the transition strength is greater than 10 6 times the f-f transition strength, and the above, only a small amount of rare earth compound can achieve a large amount of absorption of blue light, and a small amount of doping will not cause a large number of defects in the metal oxide semiconductor material, so the influence on the electron mobility is small.

[0091] In addition, according to the energy required by the f-d transition of the M FD ion in the rare earth compound, and the influence of the M FD ion on the electron mobility, different M FD ions can be selected in different doping amounts.

[0092] In addition, based on the above doping, the semiconductor matrix material of the present disclosure does not need to be widened, so In2O3 or SnO2 with a relatively narrow band gap can be selected as the semiconductor matrix material, and since the 5s orbit of adjacent In and the 5s orbit of adjacent Sn can overlap to form an electron channel, the metal oxide semiconductor material can ensure a high electron mobility.

[0093] In some embodiments, in the metal oxide semiconductor material, the element composition of the semiconductor matrix material and the at least one rare earth compound can be represented as ((M FD ) a A b )x(M c O d )1-x, wherein x is greater than or equal to 0.001 and less than or equal to 0.15. That is, (MFD ) a A b The molar ratio of the semiconductor matrix material and the at least one rare earth compound is greater than or equal to 0.1% and less than or equal to 15%.

[0094] In some embodiments, x is greater than or equal to 0.005 and less than or equal to 0.1. That is, (M FD ) a A b The molar ratio of the semiconductor matrix material and the at least one rare earth compound is greater than or equal to 0.5% and less than or equal to 10%.

[0095] In some embodiments, in the general formula (M FD ) a A b In the case where M FD is selected from one of praseodymium and terbium, x is greater than or equal to 0.01 and less than or equal to 0.1. That is, (M FD ) a A b The molar ratio of the semiconductor matrix material and the at least one rare earth compound is greater than or equal to 1% and less than or equal to 10%. At this molar ratio, absorption of most blue light can be achieved.

[0096] Here, it should be noted that, since the E fd of terbium is lower than that of praseodymium, in some embodiments, M FD in the at least one rare earth compound is selected from terbium.

[0097] In some embodiments, in the general formula (M FD ) a A b In the general formula (M FD , x of M FD selected from cerium is less than x of M FD selected from the remaining elements other than cerium. Since the electron cloud expansion effect of cerium ions is very significant, by controlling the amount of cerium doping to be small, it is also possible to avoid the impact of excessive cerium doping on mobility.

[0098] In some embodiments, in the general formula (M FD ) a A b In the case where M FD is selected from cerium, x is greater than or equal to 0.001 and less than or equal to 0.02. That is, (M FD ) a A bThe molar proportion of the rare earth compound in the semiconductor matrix material and the at least one rare earth compound is greater than or equal to 0.1% and less than or equal to 2%. At this molar proportion, the stability of the NBIS can be effectively improved while the effect of doping on mobility can be minimized.

[0099] In some embodiments, the metal oxide semiconductor material further comprises a rhenium compound. This is because rhenium ions have a larger radius and rhenium compounds themselves have a higher electron mobility, which can adjust the electron mobility of the metal oxide semiconductor material.

[0100] The anion in the rhenium compound can be one of oxygen or A. When the anion in the rhenium compound is oxygen, it is rhenium oxide. When the anion in the rhenium compound is A, the rhenium compound can be expressed as Re e A f , where e is the compound Re e A f The number of atoms of Re element in the compound, f is Re e A f The number of atoms of A in .

[0101] In some embodiments, in the metal oxide semiconductor material, the molar ratio of the rhenium compound in the rhenium compound and the semiconductor matrix material is greater than or equal to 0.02 and less than or equal to 0.15.

[0102] For example, the compound of rhenium is Re e A f For example, the elemental composition of rhenium compounds and semiconductor matrix materials can be expressed as: (Re e A f ) y (M c O d ) 1-y , at this time, y is greater than or equal to 0.02 and less than or equal to 0.15.

[0103] Here, it should be noted that, similar to c and d above, a and b, as well as e and f, can also be integers or decimals. The specific reasons can be referred to the above description of c and d.

[0104] Here, in the general formula (M FD ) a A b In M FD For example, when A is selected from praseodymium and A is selected from bromine, a may be equal to 1 and b may be equal to 3, or a may be equal to 1 and b may be equal to 2.95.

[0105] In some embodiments, in each rare earth compound included in the metal oxide semiconductor material, MFD The minimum energy required for an element to undergo fd transition and / or charge transfer transition is less than 2.64 eV.

[0106] In these embodiments, the metal oxide semiconductor material is formed by increasing the M of each rare earth compound contained in the metal oxide semiconductor material. FD The minimum energy required for the element to undergo fd transition and / or charge transfer transition is limited to a range of less than 2.64 eV, corresponding to light with a wavelength greater than 470 nm, and can absorb most of the blue light in the backlight source and self-luminescence.

[0107] Here, according to the various M in Table 1 FD Ionic E fd Different, you can choose the appropriate E according to the above minimum energy range fd M FD ions and A ions, for example, in the case where A is selected from sulfur, selenium, tellurium, phosphorus, arsenic or boron, except E fd For the elements other than praseodymium, terbium and cerium, the minimum energy required for fd transition and / or charge transfer transition can be limited to a range of less than 2.64 eV.

[0108] According to the backlight source and the self-luminescence also contain 470nm~500nm blue light, therefore, optionally, in each rare earth compound contained in the metal oxide semiconductor material, M FD The minimum energy required for an element to undergo fd transition and / or charge transfer transition is greater than 2.48 eV.

[0109] By putting M FD The minimum energy required for an element to undergo fd transition and / or charge transfer transition is limited to a range greater than 2.48 eV, corresponding to light with a wavelength less than 500 nm. Since metal oxide semiconductor materials are insensitive to light greater than 500 nm, the stability of NBIS can be significantly improved by simply absorbing light less than 500 nm.

[0110] Here, in M FD When selected from praseodymium or terbium, A is selected from sulfur, selenium, tellurium, phosphorus, arsenic or boron, so that M FD The minimum energy required for the fd transition of an ion can be greater than 2.48 eV.

[0111] Some embodiments of the present disclosure provide an application of a metal oxide semiconductor material in a semiconductor device. The metal oxide semiconductor material includes a semiconductor matrix material and at least one rare earth compound doped in the semiconductor matrix material, wherein the general formula of each rare earth compound is (M FD ) a A b In the general formula (M FD )a A b In, M FD Selected from rare earth elements, one of the elements capable of fd transition and / or charge transfer transition, A is selected from the element capable of making the corresponding M FD The absorption spectrum of the fd transition is red-shifted to the visible light band, and a is the general formula (M FD ) a A b Element M FD is the number of atoms of element A, and b is the number of atoms of element A.

[0112] Here, regarding the semiconductor matrix material and the rare earth compound (M FD ) a A b The description of the semiconductor matrix material and the rare earth compound (M FD ) a A b The introduction of , will not be repeated here.

[0113] In some embodiments, the semiconductor device may include an integrated circuit, a photodetector, a semiconductor light emitting diode, a semiconductor laser, a photocell, and the like.

[0114] Some embodiments of the present disclosure provide a target material, comprising a metal oxide semiconductor material, wherein the metal oxide semiconductor material comprises a semiconductor matrix material, and at least one rare earth compound doped in the semiconductor matrix material, wherein the general formula of each rare earth compound is represented by (M FD ) a A b In the general formula (M FD ) a A b In, M FD Selected from rare earth elements, one of the elements capable of fd transition and / or charge transfer transition, A is selected from the element capable of making the corresponding M FD Elements with absorption spectra that undergo fd transition and / or charge transfer transition and whose wavelength band is red-shifted to the visible light band, a is a general formula (M FD ) a A b Element M FD is the number of atoms of element A, and b is the number of atoms of element A.

[0115] Here, the semiconductor matrix material and the rare earth compound (M FD ) a A b The description of the semiconductor matrix material and the rare earth compound (M FD )a A b The introduction of , will not be repeated here.

[0116] According to the fact that the target material needs a high temperature of more than 1000° C. during sintering, it can be known that in some embodiments, the general formula (M FD ) a A b In the embodiment, A is selected from one of sulfur, selenium, tellurium, arsenic and boron. That is, when A is selected from one of sulfur, selenium, tellurium, arsenic and boron, the target material can be ensured to have good stability during production.

[0117] Some embodiments of the present disclosure provide a method for preparing a target material, such as Figure 4 Shown, including:

[0118] S101, doping at least one rare earth compound into the semiconductor matrix material in proportion and mixing them evenly. The general formula of each rare earth compound is (M FD ) a A b , in the general formula (M FD ) a A b In, M FD Selected from rare earth elements, one of the elements capable of fd transition and / or charge transfer transition, A is selected from the element capable of making the corresponding M FD Elements with absorption spectra that undergo fd transition and / or charge transfer transition and whose wavelength bands are red-shifted to the visible light band, a is a general formula (M FD ) a A b Element M FD is the number of atoms of element A, and b is the number of atoms of element A.

[0119] Here, the semiconductor matrix material and the rare earth compound (M FD ) a A b For a detailed introduction, please refer to the above metal oxide semiconductor materials for semiconductor matrix materials and rare earth compounds (M FD ) a A b The description is not repeated here.

[0120] S102 , subjecting the uniformly mixed semiconductor matrix material doped with the at least one rare earth compound to ball milling, hot pressing or slurry casting, and sintering to obtain a target material.

[0121] In some embodiments, in the general formula (M FD ) a A bIn the embodiment, A is selected from one of sulfur, selenium, tellurium, arsenic and boron. According to the above sintering at a temperature above 1000 ° C, it can be known that selecting one of sulfur, selenium, tellurium, arsenic and boron as an anion can enhance (M FD ) a A b Stability during the above high temperature sintering process.

[0122] Some embodiments of the present disclosure provide a method for preparing a thin film transistor, such as Figure 5 Shown, including:

[0123] S201, forming a semiconductor thin film 100 on a substrate 11, wherein the material of the semiconductor thin film 100 includes a semiconductor matrix material and at least one rare earth compound doped in the semiconductor matrix material, wherein the general formula of each rare earth compound is expressed as (M FD ) a A b , in the general formula (M FD ) a A b In, M FD Selected from rare earth elements, one of the elements that can undergo fd transition, A is selected from the element that can make the corresponding M FD The absorption spectrum of the fd transition is red-shifted to the visible light band, and a is the general formula (M FD ) a A b Element M FD is the number of atoms of element A, and b is the number of atoms of element A.

[0124] Here, taking the thin film transistor 1 as a bottom-gate thin film transistor as an example, before forming the semiconductor thin film 100 on the base substrate 11, a gate 13 and a gate insulating layer 14 may be formed on the base substrate 11. The gate 13 may be obtained by sputtering, depositing a metal thin film, and patterning the metal thin film, and the gate insulating layer 14 may be obtained by spin coating, drop coating, printing, anodizing, thermal oxidation, physical vapor deposition, or chemical vapor deposition, and patterning. The thickness of the gate 13 may be 100 to 500 nm, and the thickness of the gate insulating layer 14 may be 100 to 1000 nm.

[0125] Here, the semiconductor matrix material and the rare earth compound (M FD ) a A b The detailed introduction of semiconductor matrix materials and rare earth compounds (M FD ) a A b The description is not repeated here.

[0126] The semiconductor thin film 100 can be prepared by deposition or solution method, which is not specifically limited herein. The deposition includes, but is not limited to, sputtering, pulsed laser deposition, atomic layer deposition, etc. The solution method includes, but is not limited to, spin coating, inkjet printing, screen printing, blade coating, and imprinting, etc.

[0127] In some embodiments, in the at least one rare earth compound, in the case where A is selected from one or more of sulfur, selenium, tellurium, arsenic, and boron, forming the semiconductor thin film 100 on the substrate 11 comprises:

[0128] A target comprising a metal-oxide semiconductor material is provided.

[0129] The target can be prepared by the above-mentioned method for preparing a target.

[0130] The semiconductor thin film 100 is formed on the substrate 11 by a sputtering process.

[0131] Alternatively, targets comprising the at least one rare earth compound and the semiconductor matrix material, respectively, are provided.

[0132] The semiconductor thin film 100 is formed on the substrate 11 by a dual-target sputtering process.

[0133] In these embodiments, in the case where the rare earth compound is one, M FD may be selected from one of cerium, praseodymium, neodymium, promethium, samarium, terbium, and dysprosium, and A can be selected from one of sulfur, selenium, tellurium, arsenic, and boron. In this case, the rare earth compound can be Pr2S3, for example. In the case where the rare earth compound is multiple, M FD may be selected from one or more of cerium, praseodymium, neodymium, promethium, samarium, terbium, and dysprosium, and A can be selected from one or more of sulfur, selenium, tellurium, arsenic, and boron. In this case, the at least one rare earth compound can include Pr2S3 and Tb2S3, for example, M FD may be selected from multiple of cerium, praseodymium, neodymium, promethium, samarium, terbium, and dysprosium, and A can be selected from one of sulfur, selenium, tellurium, arsenic, and boron. In this case, the at least one rare earth compound can include Pr2S3 and Tb2Te3, for example, M FD may be selected from multiple of cerium, praseodymium, neodymium, promethium, samarium, terbium, and dysprosium, and A can be selected from multiple of sulfur, selenium, tellurium, arsenic, and boron.

[0134] In some embodiments, in the at least one rare earth compound, in the case where A is selected from one or more of bromine and iodine, forming the semiconductor thin film 100 on the substrate 11 comprises:

[0135] The semiconductor thin film 100 is formed on the substrate 11 by a solution method.

[0136] The solution preparation method used in the solution method can be a dispersion method, in which the nanometer powder of the rare earth compound and the nanometer powder of the semiconductor matrix material can be dispersed in a solvent to form a suspension. Then a liquid film of the suspension is formed on the substrate 11 by spin coating, inkjet printing, screen printing, blade coating or stamping, and then the solvent is removed to obtain the semiconductor thin film 100.

[0137] After the semiconductor thin film 100 is formed on the substrate 11, the semiconductor thin film 100 can also be annealed, and the annealing temperature can be 200-500°C. The thickness of the semiconductor thin film 100 after annealing can be 5-80 nm.

[0138] Here, it should be noted that since the semiconductor thin film 100 is annealed after being formed, in order to improve the dispersion effect of the semiconductor matrix material, the semiconductor matrix material can be selected as a precursor of the semiconductor matrix material during preparation.

[0139] Unlike the semiconductor matrix material, in order to avoid the formation of rare earth oxides after annealing, the rare earth compound can be directly selected from (M FD ) a A b .

[0140] In these embodiments, in order to improve the dispersion uniformity of the rare earth compound, A in the at least one rare earth compound is selected from one or more of bromine and iodine, that is, the solubility of the rare earth compound in the solvent can be improved, and (M FD ) a A b , which can avoid decomposition to form rare earth oxides during subsequent annealing.

[0141] For example, when the rare earth compound is PrBr3 and the semiconductor matrix material is In2O3, PrBr3 and In2O3 precursor In(NO)3 can be dissolved in deionized water, and the molar ratio of PrBr3 and In(NO)3 is adjusted, and then a semiconductor thin film is formed by spin coating, annealing and other processes. In the annealing process, In(NO)3 is decomposed to obtain In2O3, and PrBr3 does not decompose, so that a semiconductor thin film doped with PrBr3 can be obtained.

[0142] And in the case where the rare earth compound is TbI3 and the semiconductor matrix material is SnO2, TbI3 and SnO2 can be dispersed in a solvent to obtain a suspension, and the molar ratio of TbI3 and SnO2 is adjusted, and then a semiconductor thin film is formed by spin coating, annealing and other processes. In the annealing process, TbI3 does not decompose, so that a semiconductor thin film 100 doped with TbI3 can be obtained.

[0143] Here, it is to be noted that, in the case where the rare earth compound is one kind, M FD may be selected from one of cerium, praseodymium, neodymium, promethium, samarium, terbium and dysprosium, and A can be selected from one of bromine and iodine, such as the rare earth compound can be PrBr3. In the case where the rare earth compound is more than one kind, M FD may be selected from one or more of cerium, praseodymium, neodymium, promethium, samarium, terbium and dysprosium, and A can be selected from one or more of bromine and iodine, such as the at least one rare earth compound can include PrBr3and TbI3.

[0144] S202, the semiconductor thin film 100 is patterned to obtain the active layer 12 of the thin film transistor 1.

[0145] The semiconductor thin film 100 can be patterned by coating photoresist 200 on the semiconductor thin film 100, and then through exposure, development and etching processes.

[0146] After the active layer 12 is prepared, S203 can also be included to form the source 15 and the drain 16 on the substrate 11 on which the active layer 12 is formed. For example, a conductive thin film can be formed by evaporation or deposition, and the source 15 and the drain 16 can be formed by coating photoresist, exposure, development, etching and the like. The thickness of the source 15 and the drain 16 can be 100-1000 nm.

[0147] Based on the above detailed description, in order to objectively evaluate the technical effects of the technical solutions provided by the present disclosure, the following will describe the technical solutions provided by the present disclosure in detail through application examples, comparative examples and experimental examples.

[0148] Application Example 1

[0149] Application Example 1 provides a thin film transistor, and the preparation method thereof is as follows:

[0150] Step 1), a layer of Al:Nd (aluminum-neodymium alloy) film with a thickness of 300 nm is formed on the substrate 11 by sputtering, and the gate 13 is formed by coating photoresist, exposure, development and the like.

[0151] The substrate 11 can be glass containing a buffer layer.

[0152] Step 2), an insulating layer is prepared by an anodization method to form a layer of gate oxide layer (Al2O3: Nd, aluminum-neodymium oxide) 14 with a thickness of 200 nm.

[0153] Step 3), the TbB6 material and the In2O3 material are prepared into two targets respectively, and the two targets are installed on different target positions, and then sputtering is performed to form (TbB6) on the substrate 11 on which the gate insulating layer 14 is formed. x (In2O3) 1-x Thin film. The active layer 12 is formed by coating photoresist, exposure, development and other steps.

[0154] The element composition of the active layer 12 is represented as (TbB6) x (In2O3) 1-x , wherein 0.001≤x≤0.15, and parallel tests are performed with x equal to 0.001, 0.01, 0.05, 0.1 and 0.15 respectively.

[0155] Step 4), a 240nm-thick indium tin oxide (ITO, Indium Tin Oxides) metal oxide thin film is formed on the substrate 11 on which the active layer 12 is formed by sputtering, and the source electrode 15 and the drain electrode 16 are formed by patterning process.

[0156] Step 5), the prepared thin film transistor 1 is annealed at 300°C for 1 hour in an atmospheric environment. TFTs with x equal to 0.001, 0.01, 0.05, 0.1 and 0.15 respectively are obtained.

[0157] Experimental Example 1

[0158] The transfer characteristic curves of the TFT in the above application example 1 and the TFT with x equal to 0 made under the same conditions are tested, the test condition is NBIS condition, LED (Light-Emitting Diode, Light-Emitting Diode) white light irradiation, and the gate bias is -30V.

[0159] After the test is completed, the threshold voltage drift amount (ΔV th ) of the TFT in the application example 1 and the TFT with x equal to 0 made under the same conditions in unit time under the NBIS condition is calculated, and the electron mobility can be calculated according to the formula of the transfer characteristic saturation region, by substituting the current value and the threshold voltage of the corresponding region. Among them, the calculation results of the threshold voltage drift amount (ΔV th ) and the electron mobility are shown in Table 3.

[0160] Table 3

[0161]

[0162] In Table 3, ΔV th represents the threshold voltage drift amount per hour. As can be seen from Table 3, in the case of x equal to 0.001, the ΔV thcan be greatly reduced; in the case of x increasing to 0.01, ΔV th can be controlled within 3V, basically meeting the application requirements; in the case of x being equal to 0.05, ΔV th is minimum, 0.8V. It can be seen that, with the increase of the doping amount of TbB6, ΔV th under NBIS presents a decreasing trend as a whole, but ΔV th under NBIS slightly increases when x is greater than 0.05, which shows that only a small amount of TbB6 needs to be doped to greatly reduce the threshold voltage drift, and with the continuous increase of the doping amount, the reduction of the threshold voltage offset is not obvious, and even there is a rebound trend. With the gradual increase of the value of x, the electron mobility gradually decreases, and it can be known that, in the case of x being equal to 0.05, the stability under NBIS of the TFT can be improved while the electron mobility is kept relatively high. The problem of mutual restriction between the electron mobility and the NBIS stability of the metal oxide semiconductor material in the related art is solved.

[0163] In addition, when the electrical properties of the device are tested under the NBIS condition, it is found that, in the case of x being equal to 0, the carrier concentration in the active layer 12 is very large, and the threshold voltage of the thin film transistor 1 is relatively negative, which is difficult to turn off. After doping TbB6, the carrier concentration in the active layer 12 decreases, and the threshold voltage of the thin film transistor 1 can be regulated to the positive direction. This shows that, after doping TbB6, TbB6 also has the effect of inhibiting oxygen vacancies and reducing carrier concentration, which can further improve the light stability of the metal oxide semiconductor TFT.

[0164] Application Example 2

[0165] Application Example 2 provides a thin film transistor, and the steps 1), 2) and 4) of the preparation method of the thin film transistor are basically the same as the steps 1), 2) and 4) in the above Application Example 1, which will not be repeated here.

[0166] The difference is that, in step 3), the target material containing Pr2S3, In2O3 and ZnO is fixed on the target position, and a (Pr2S3) x (In 5.2 Zn 1.0 O y ) 1-x thin film with a thickness of 20nm is formed on the substrate with a gate insulating layer by using a single-target sputtering method, and is annealed at 250℃ for 1h after sputtering. Then, the active layer 12 is formed by using the steps of coating photoresist, exposure, development and the like. Wherein, x is equal to 0.09, and y can be 8.8 or 9.

[0167] After the source electrode 15 and the drain electrode 16 are prepared, a step 5) of preparing an Al2O3 layer as a passivation layer is further included.

[0168] wherein the Pr2S3, In2O3 and ZnO are formed on the substrate 11 having the gate insulating layer 14 by a single-target sputtering method with a thickness of 20 nm. x (In 5.2 Zn 1.0 O y ) 1-x Before the thin film is prepared, the nanomaterials of Pr2S3, In2O3 and ZnO can be uniformly blended in a corresponding ratio, and then prepared into a target material containing Pr2S3, In2O3 and ZnO through ball milling, slurry casting and sintering processes.

[0169] Comparative Example

[0170] The preparation method of the comparative example is basically the same as that of the TFT in Application Example 2, except that Pr2O3 is used to dope the active layer 12 in the comparative example, that is, the element composition of the active layer 12 is represented as (Pr2O3) x (In 5.2 Zn 1.0 O y ) 1-x , wherein x and y are the same as in Application Example 2.

[0171] Experimental Example 2

[0172] The transfer characteristic curves of the TFTs obtained in Application Example 2 and the comparative example are tested, and the test conditions are NBIS conditions, LED white light irradiation, a gate bias of -30 V, and test times corresponding to times of 0 s, 100 s, 600 s, 1200 s and 3600 s after the application of the gate bias. The test results are shown in FIGS. Figure 6 and Figure 7 .

[0173] As can be seen from Figure 6 and Figure 7 , the threshold voltage drift (ΔV th ) of the Pr2O3-doped TFT under NBIS is 9.2 V / hour, and the mobility is calculated to be 22.1 cm 2 / Vs. The threshold voltage drift (ΔV th ) of the Pr2S3-doped TFT under NBIS is 1.4 V / hour, and the mobility is as high as 34.2 cm 2 / Vs.

[0174] Therefore, it can be concluded that the Pr2S3-doped TFT has a higher mobility than the Pr2O3-doped TFT, and also has more obvious and better NBIS stability.

[0175] Experimental Example 3

[0176] The absorption spectrum test was performed on the Pr2S3 doped semiconductor film prepared in the above application example 2 and the Pr2O3 doped semiconductor film prepared in the comparative example. Figure 8 Shown is a comparison of the absorption spectra of Pr2S3-doped semiconductor films and Pr2O3-doped semiconductor films.

[0177] Depend on Figure 8 It can be seen that the absorption edge of the absorption spectrum of the Pr2O3-doped semiconductor film is around 430nm, while the absorption edge of the absorption spectrum of the Pr2S3-doped semiconductor film is significantly red-shifted to between 500-600nm, indicating that the combination of S anions and Pr has an electron cloud expansion effect, which can effectively red-shift the absorption spectrum of the fd transition to the blue light or even green light region, thereby greatly improving the NBIS stability.

[0178] Here, it should be noted that due to the E of the trivalent ions of Pr and Tb fd Therefore, under the same anion environment, the value of x has the same variation trend as the threshold voltage shift and electron mobility under the corresponding NBIS.

[0179] Application Example 3

[0180] Application Example 3 provides a thin film transistor. Step 1) and step 2) of the method for preparing the thin film transistor are substantially the same as step 1) and step 2) in the above Application Example 1, and are not described again here.

[0181] The difference is that in step 3), the active layer 12 is prepared by a solution method. After the active layer 12 is prepared, an aluminum thin film is prepared by evaporation, and then the source electrode 15 and the drain electrode 16 are formed by a patterning process.

[0182] Among them, three different rare earth compounds (such as NdBr3, PrBr3 and PrCl3) were used to dope the semiconductor matrix material, and three groups of TFTs doped with different rare earth compounds (such as NdBr3, PrBr3 and PrCl3) were made for comparison. In these three groups of TFTs, the molar proportion of rare earth compounds in rare earth compounds and In2O3 is the same as x.

[0183] Here, taking the rare earth compound NdBr3 as an example, the method for preparing the active layer 12 by the solution method includes the following steps:

[0184] (1) Prepare a solution of NdBr3 and In(NO3)3.

[0185] The total molar concentration of the solution is 0.2 mol / L, then the mass of NdBr3 and In(NO3)3 is calculated according to the molar ratio of NdBr3 in NdBr3 and In2O3, and weighed, deionized water is used as the solvent, and stirred for 12 h to obtain the solution of NdBr3 and In(NO3)3.

[0186] (2) The solution of NdBr3 and In(NO3)3 is spin-coated on the substrate 11 with the gate 13 and the gate insulating layer 14, and the spin-coating process is divided into two stages, the first stage is low-speed spin-coating, the rotation speed can be 500 rpm, and the time can be 3 s, and the second stage is high-speed spin-coating, the rotation speed can be 5000 rpm, and the time can be 40 s.

[0187] (3) First, pre-baking at 40℃ for 20 min; then heating to 90℃ for 10 min to remove the solvent, then placing into a mask plate for UV(Ultraviolet) irradiation for 30 min, then etching with a solvent to realize patterning, and finally high-temperature annealing (250℃ for 1 h) to form the active layer 12.

[0188] Experimental Example 4

[0189] The transfer characteristic curve of the TFT obtained in the above application example 3 is tested, the test condition is NBIS condition, LED white light is used for irradiation, and the gate bias voltage is -30 V.

[0190] After the test is completed, the threshold voltage drift amount (ΔVth) per unit time of the TFT in application example 3 under the NBIS condition is calculated. th The calculation result is shown in Table 4.

[0191] Table 4

[0192]

[0193] As shown in Table 4, under the same anion environment, the NBIS stability of the thin film transistor 1 with Pr as the cation is better than that of the thin film transistor 1 with Nd as the cation; and under the same cation environment, the NBIS stability of the thin film transistor 1 with Br as the anion is better than that of the thin film transistor 1 with Cl as the anion. This is consistent with the analysis of the E fd and the electronegativity of the anion.

[0194] Here, it should be noted that since the electron mobility of the TFT is also related to the preparation method, therefore, the electron mobility of the TFT prepared by the solution method (preparing the active layer) is generally smaller than that of the TFT prepared by deposition (preparing the active layer), and the value of the electron mobility of the TFT is not described here, and in actual application, a person skilled in the art can select a suitable preparation method according to the needs.

[0195] In summary, by doping a small amount of rare earth compounds in the semiconductor matrix material, and selecting the anion of the rare earth compound, the threshold voltage shift under negative gate bias light stress can be greatly reduced, the illumination stability of the TFT under NBIS can be improved, and a relatively high electron mobility can be maintained. The problem of mutual restriction between electron mobility and NBIS stability of metal oxide semiconductor material in the related art is solved. It is found through experiments that by adjusting the doping ratio of the rare earth compound, the threshold voltage drift of the thin film transistor under light and-30V gate voltage stress can be controlled to be less than 3V per hour, and even the threshold voltage drift of most thin film transistors under light and-30V gate voltage stress can reach less than 2V per hour, which has good application effect.

[0196] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can think of changes or replacements within the technical range disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A metal oxide semiconductor material, characterized in that: include: Semiconductor matrix materials; as well as At least one rare earth compound doped in the semiconductor matrix material, each rare earth compound having a general formula represented by (M FD ) a A b ; In the general formula (M FD ) a A b In, M FD One of the rare earth elements capable of undergoing fd transition and / or charge transfer transition, M FD One of the remaining elements in the lanthanide metal series except lanthanum; A is selected from the group consisting of FD The element whose absorption spectrum band undergoing fd transition and / or charge transfer transition is red-shifted to the visible light band, A is selected from one of the elements having less electronegativity than oxygen; a is a general formula (M FD ) a A b Element M FD is the number of atoms of element A, and b is the number of atoms of element A.

2. The metal oxide semiconductor material according to claim 1, characterized in that In the general formula (M FD ) a A b In, M FD One selected from the group consisting of cerium, praseodymium, neodymium, promethium, samarium, terbium and dysprosium.

3. The metal oxide semiconductor material according to claim 2, characterized in that In the general formula (M FD ) a A b In, M FD Selected from one of praseodymium and terbium.

4. The metal oxide semiconductor material according to claim 1, characterized in that In the general formula (M FD ) a A b wherein A is selected from one of sulfur, selenium, tellurium, bromine, iodine, arsenic and boron.

5. The metal oxide semiconductor material according to any one of claims 1 to 4, characterized in that In each rare earth compound contained in the metal oxide semiconductor material, M FD The minimum energy required for an element to undergo an fd transition is less than 2.64 eV.

6. The metal oxide semiconductor material according to claim 5, characterized in that In each rare earth compound contained in the metal oxide semiconductor material, M FD The minimum energy required for an element to undergo an fd transition is greater than 2.48 eV.

7. The metal oxide semiconductor material according to any one of claims 1 to 4, characterized in that The semiconductor matrix material comprises at least one first metal oxide and / or at least one second metal oxide, wherein the general formula of each first metal oxide and each second metal oxide is represented by M c O d ; In each first metal oxide, the general formula M c O d Wherein M is selected from one of indium, zinc, gallium, tin and cadmium; In each second metal oxide, the general formula M c O d Where M is selected from any combination of two or more of indium, zinc, gallium, tin and cadmium; c is the general formula M c O d where M is the number of atoms and d is the number of atoms of element oxygen in the general formula.

8. The metal oxide semiconductor material according to claim 7, characterized in that In the general formula M c O d In the above, M also includes one or a combination of any two or more of lanthanide metals, scandium and yttrium.

9. The metal oxide semiconductor material according to any one of claims 1 to 4, characterized in that In the metal oxide semiconductor material, the elemental composition of the semiconductor matrix material and the at least one rare earth compound is represented by ((M FD ) a A b ) X (M c O d ) 1-X ; Wherein, x is greater than or equal to 0.001 and less than or equal to 0.

15.

10. The metal oxide semiconductor material according to claim 9, characterized in that In the general formula (M FD ) a A b In M FD In the case of one selected from praseodymium and terbium, x is greater than or equal to 0.01 and less than or equal to 0.

1.

11. The metal oxide semiconductor material according to claim 9, characterized in that In the general formula (M FD ) a A b In M FD When selected from cerium, x is greater than or equal to 0.001 and less than or equal to 0.

02.

12. A target material, characterized in that: The method comprises the metal oxide semiconductor material according to any one of claims 1 to 11.

13. The target material according to claim 12, characterized in that The metal oxide semiconductor material in the general formula (M FD ) a A b wherein A is selected from one of sulfur, selenium, tellurium, arsenic and boron.

14. A thin film transistor, characterized in that: include: An active layer, wherein the material of the active layer comprises the metal oxide semiconductor material according to any one of claims 1 to 11.

15. A method for preparing a target material, characterized in that: include: Doping at least one rare earth compound into the semiconductor matrix material in proportion and mixing them evenly; The general formula of each rare earth compound is (M FD ) a A b , in the general formula (M FD ) a A b In, M FD One of the rare earth elements capable of undergoing fd transition and / or charge transfer transition, M FD is selected from one of the remaining elements in the lanthanide metal series except lanthanum; A is selected from an element that can red-shift the absorption spectrum of the corresponding MFD to the visible light band, and A is selected from one of the elements with less electronegativity than oxygen; a is a general formula (M FD ) a A b Element M FD The number of atoms of element A, b is the number of atoms of element A; The semiconductor matrix material doped with the at least one rare earth compound after uniform mixing is subjected to ball milling, hot pressing or slurry casting, and sintering to obtain the target material.

16. The method for preparing a target material according to claim 15, wherein: In the general formula (M FD ) a A b wherein A is selected from one of sulfur, selenium, tellurium, arsenic and boron.

17. A method for preparing a thin film transistor, characterized in that: include: A semiconductor thin film is formed on a substrate. The material of the semiconductor thin film includes a metal oxide semiconductor material. The metal oxide semiconductor material includes: a semiconductor matrix material and at least one rare earth compound doped in the semiconductor matrix material. The general formula of each rare earth compound is expressed as (M FD ) a A b , in the general formula (M FD ) a A b In, M FD One of the rare earth elements capable of undergoing fd transition and / or charge transfer transition, M FD One of the remaining elements in the lanthanide metal series except lanthanum; A is selected from the group consisting of FD The element whose absorption spectrum band undergoing fd transition and / or charge transfer transition is red-shifted to the visible light band, A is selected from one of the elements having less electronegativity than oxygen; a is a general formula (M FD ) a A b Element M FD The number of atoms of element A, b is the number of atoms of element A; The semiconductor thin film is patterned to obtain the active layer of the thin film transistor.

18. The method for preparing a thin film transistor according to claim 17, wherein: In the at least one rare earth compound, when A is selected from one or more of sulfur, selenium, tellurium, arsenic and boron, the step of forming a semiconductor thin film on a substrate comprises: Providing a target material comprising the metal oxide semiconductor material; forming the semiconductor thin film on the substrate by a sputtering process; or, providing targets comprising the at least one rare earth compound and the semiconductor matrix material, respectively; The semiconductor thin film is formed on the substrate by a dual-target sputtering process.

19. The method for preparing a thin film transistor according to claim 17, wherein: In the at least one rare earth compound, when A is selected from one or more of bromine and iodine, the step of forming a semiconductor thin film on a substrate comprises: The semiconductor thin film is formed on the base substrate by a solution method.

20. The method for preparing a thin film transistor according to claim 19, wherein: The solution method includes one of spin coating, inkjet printing, screen printing, doctor blade coating and stamping.

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