Thin film transistor, preparation method thereof and display panel

Abstract

The invention discloses a thin film transistor and a preparation method thereof, and a display panel. The thin film transistor comprises a first grid electrode; the first insulating layer is positioned on one side of the first grid electrode; the active layer is arranged on the side, away from the first grid electrode, of the first insulating layer, the active layer is a continuous film layer in the thickness direction, the material of the active layer comprises oxide, and meanwhile the active layer comprises a first active sub-layer and a second active sub-layer which are sequentially arranged in a stacked mode in the direction away from the first grid electrode; the mobility of the first active sub-layer is higher than that of the second active sub-layer. According to the design of the invention, high stability and high mobility of the thin film transistor can be ensured, and the device performance of the thin film transistor can be prevented from being influenced by interface defects and interface barriers in the laminated structure.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a thin film transistor and a method for preparing the same, and a display panel. Background Art

[0002] Thin film transistors (TFTs) are used in display panels to control the flow of current. The control function is performed by a semiconductor material called an active layer in the thin film transistor, which is usually made of silicon, silicon oxide or silicon nitride.

[0003] However, the inventors of the present application have found that current thin film transistors have problems such as low mobility and poor device stability. Summary of the invention

[0004] The present application provides a thin film transistor and a preparation method thereof, and a display panel, which can not only ensure high stability and high mobility of the thin film transistor, but also prevent interface defects and interface barriers in the stacked structure from affecting the device performance of the thin film transistor.

[0005] A first aspect of an embodiment of the present application provides a thin film transistor, comprising: a first gate; a first insulating layer located on one side of the first gate; an active layer arranged on a side of the first insulating layer away from the first gate, wherein the active layer is a continuous film layer in the thickness direction and the material of the active layer includes an oxide, and the active layer includes a first active sublayer and a second active sublayer stacked in sequence in a direction away from the first gate, and the mobility of the first active sublayer is higher than the mobility of the second active sublayer.

[0006] A second aspect of an embodiment of the present application provides a display panel, wherein the display panel comprises the thin film transistor in any one of the above items.

[0007] A third aspect of an embodiment of the present application provides a method for preparing a thin film transistor, the method comprising: forming a first gate, a first insulating layer and an active layer; wherein the first gate, the first insulating layer and the active layer are stacked in sequence, and the material of the active layer comprises an oxide, and the active layer comprises a first active sublayer and a second active sublayer stacked in sequence in a direction away from the first gate, the mobility of the first active sublayer is higher than the mobility of the second active sublayer, and the active layer is prepared by a continuous film forming process.

[0008] The beneficial effects are: on the one hand, the present application sets an active layer including a first active sublayer and a second active sublayer, which can make the thin film transistor have both high mobility and high stability. On the other hand, the active layer is set to be a continuous film layer in the thickness direction, that is, in the process of preparing the active layer, the coating process of the active layer will not be interrupted, and only other parameters such as gas concentration and gas ratio will change, so that there is no film layer interface in the active layer, that is, there is no film layer interface between the first active sublayer and the second active sublayer. Compared with the prior art in which the active layer is a stacked structure, the present application can avoid interface defects and interface barriers in the stacked structure affecting the device performance of the thin film transistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0010] Figure 1 It is a schematic structural diagram of an embodiment of a thin film transistor of the present application;

[0011] Figure 2 is a schematic structural diagram of another embodiment of the thin film transistor of the present application;

[0012] Figure 3 is a structural schematic diagram of another embodiment of the thin film transistor of the present application;

[0013] Figure 4 It is a schematic structural diagram of an embodiment of a display panel of the present application. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0015] It should be noted that the terms "first" and "second" in this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0016] See also Figure 1 In one embodiment of the present application, the thin film transistor 10 includes a first gate 110 , a first insulating layer 120 and an active layer 130 .

[0017] The first gate 110 is made of a conductive material and is used as a control terminal of the thin film transistor 10. The first insulating layer 120 is located on one side of the first gate 110 and is used to achieve insulation between the two electrodes. The material of the first insulating layer 120 can be an inorganic material, an organic material, or a mixture of an inorganic material and an organic material. The present application does not limit the material of the first insulating layer 120 as long as it is insulating.

[0018] The active layer 130 is arranged on the side of the first insulating layer 120 away from the first gate 110, wherein the active layer 130 is a continuous film layer in the thickness direction and the material of the active layer 130 includes oxide, and the active layer 130 includes a first active sublayer 131 and a second active sublayer 132 which are stacked in sequence in a direction away from the first gate 110, and the mobility of the first active sublayer 131 is higher than the mobility of the second active sublayer 132.

[0019] Specifically, the material of the active layer 130 includes oxide, for example, the material of the active layer 130 includes indium gallium zinc oxide (IGZO) or indium zinc tin oxide (IZTO). It should be noted that the present application does not limit the specific material of the oxide.

[0020] Among them, compared with the second active sublayer 132, the first active sublayer 131 is closer to the first gate 110, and the mobility of the first active sublayer 131 is higher than the mobility of the second active sublayer 132, so that the stability of the first active sublayer 131 is lower than the stability of the second active sublayer 132. Therefore, the active layer 130 is set to include both the first active sublayer 131 and the second active sublayer 132, so that the thin film transistor 10 can have both high mobility and high stability.

[0021] Meanwhile, the active layer 130 is a continuous film layer in the thickness direction, that is, it is prepared by a continuous film forming process. Specifically, during the process of preparing the active layer 130, the coating process of the active layer 130 will not be interrupted, and only other parameters such as the concentration of the gas and the proportion of the gas will change, so that there is no film layer interface in the active layer 130, that is, Figure 1 There is no film interface between the first active sublayer 131 and the second active sublayer 132. Compared with the prior art in which the active layer 130 is a stacked structure, the present application can not only ensure the high stability and high mobility of the thin film transistor 10, but also avoid the interface defects and interface barriers in the stacked structure affecting the device performance of the thin film transistor 10.

[0022] Continue reading Figure 1 The thin film transistor 10 further includes a source electrode 1301 and a drain electrode 1302, wherein the active layer 130 includes a channel region and a source region and a drain region located on both sides of the channel region, wherein the source electrode 1301 is connected to the source region of the active layer 130, the drain electrode 1302 is connected to the drain region of the active layer 130, and the orthographic projection of the first gate electrode 110 on the active layer 130 coincides with the channel region. The source electrode 1301 and the drain electrode 1302 are conventional structures in the art and are not described one by one here.

[0023] In one embodiment, the thickness of the first active sublayer 131 is less than the thickness of the second active sublayer 132. Specifically, considering that the first active sublayer 131 has high mobility but reduces the stability of the thin film transistor 10, the thickness of the first active sublayer 131 is set to be less than the thickness of the second active sublayer 132 to ensure that the thin film transistor 10 has high stability.

[0024] Of course, in other embodiments, the thickness of the first active sublayer 131 may be greater than the thickness of the second active sublayer 132 to further improve the mobility of the thin film transistor 10, or the thickness of the first active sublayer 131 may be equal to the thickness of the second active sublayer 132. In short, the present application does not limit the thickness comparison of the first active sublayer 131 and the second active sublayer 132.

[0025] In one embodiment, the thickness of the first active sublayer 131 is in the range of 3-10 nm, for example, the thickness of the first active sublayer 131 is 3 nm, 5 nm, 8 nm or 10 nm, etc. Of course, in other embodiments, the thickness of the first active sublayer 131 can also be other, for example, equal to 20 nm or 30 nm, etc., which can be set according to actual needs.

[0026] In one embodiment, the thickness of the second active sublayer 132 is in the range of 10-50 nm, for example, the thickness of the second active sublayer 132 is 10 nm, 20 nm, 30 nm, 40 nm or 50 nm, etc. Of course, in other embodiments, the thickness of the second active sublayer 132 can also be other, for example, equal to 10 nm or 60 nm, etc., which can be set according to actual needs.

[0027] In one embodiment, in order to reduce the types of materials used, reduce costs and improve manufacturing efficiency, the first active sublayer 131 and the second active sublayer 132 are made of the same material. For example, the first active sublayer 131 and the second active sublayer 132 are made of indium gallium zinc oxide (IGZO) or indium zinc tin oxide (IZTO). Of course, the materials of the first active sublayer 131 and the second active sublayer 132 may also be different, which is not limited here.

[0028] In this embodiment, the active layer 130 also includes a first transition sublayer (not shown in the drawings) located between the first active sublayer 131 and the second active sublayer 132, wherein the mobility of the first transition sublayer gradually decreases in the direction away from the first gate 110. Specifically, the first transition sublayer is used to achieve the transition between the first active sublayer 131 and the second active sublayer 132. During the preparation process, after the preparation of the first active sublayer 131 is completed, the coating process is not interrupted, and some parameters such as the concentration of the gas and the proportion of the gas are changed so that these parameters gradually change to reach the target value, and then the second active sublayer 132 is prepared, wherein the film layer formed during the change of some parameters such as the concentration of the gas and the proportion of the gas is the first transition sublayer.

[0029] In order to achieve a smooth transition between the first active sublayer 131 and the second active sublayer 132, the mobility of the first transition sublayer decreases in a step-like manner in the direction from the first active sublayer 131 to the second active sublayer 132. Of course, in other embodiments, the mobility of the first transition sublayer may also decrease in a straight line.

[0030] In one embodiment, the thickness of the first transition sublayer is less than or equal to 3 nm, for example, the thickness of the first transition sublayer is 1 nm, 2 nm or 3 nm. The thickness of the first transition sublayer can also be set according to actual needs. In other embodiments, the thickness of the first transition sublayer can also be greater than 3 nm, for example, the thickness of the first transition sublayer is 4 nm or 5 nm.

[0031] It should be noted that, in other embodiments, the first transition sublayer may not be provided. For example, after the preparation of the first active sublayer 131 is completed, the coating process is not interrupted, and then some parameters such as the gas concentration and the gas ratio are suddenly changed to the target value, and then the second active sublayer 132 is prepared. That is to say, after the preparation of the first active sublayer 131 is completed, the preparation of the second active sublayer 132 is directly carried out.

[0032] Continue reading Figure 1 The thin film transistor 10 further includes a substrate 101, which is disposed on the side of the first gate 110 away from the first insulating layer 120. Specifically, the substrate 101 is used to provide support and insulation functions, and the material includes one of glass, plastic, and ceramic. Figure 1 The thin film transistor 10 in the embodiment may also be referred to as a bottom-gate thin film transistor.

[0033] Continue reading Figure 1 ,exist Figure 1 In the embodiment of the present invention, the thin film transistor 10 further includes a protective layer 102, which is disposed on the side of the active layer 130 away from the base substrate 101 to prevent external water vapor from invading the active layer 130. The protective layer 102 may be a single-layer structure or a stacked-layer structure. For example, the protective layer 102 may include a first inorganic layer, an organic layer, and a second inorganic layer. In short, the present application does not limit the specific structure of the protective layer 102.

[0034] Continue reading Figure 2 In another embodiment, the thin film transistor 10 further includes a second insulating layer 140 and a second gate 150 .

[0035] The second insulating layer 140 is disposed on the side of the active layer 130 away from the first gate 110; the second gate 150 is disposed on the side of the second insulating layer 140 away from the first gate 110. At this time, the thin film transistor 10 includes two gates, namely the first gate 110 and the second gate 150, so Figure 2 The thin film transistor 10 in the embodiment is also called a dual-gate thin film transistor. In order to reduce the types of materials used in the preparation process and improve the preparation efficiency, the first gate 110 and the second gate 150 are made of the same material, and the first insulating layer 120 and the second insulating layer 140 are made of the same material. Of course, in other embodiments, the materials of the first gate 110 and the second gate 150 may be different, and the materials of the first insulating layer 120 and the second insulating layer 140 may be different, which is not limited here.

[0036] At this time Figure 2In the thin film transistor 10, the active layer 130 further includes a third active sublayer 133, and the third active sublayer 133 is located on the side of the second active sublayer 132 away from the first active sublayer 131, wherein the mobility of the third active sublayer 133 is higher than the mobility of the second active sublayer 132. Specifically, at this time, because there are two gates, two high-mobility layers are provided to improve the mobility of the thin film transistor 10.

[0037] The mobilities of the first active sub-layer 131 and the third active sub-layer 133 may be equal or different, as long as they are both higher than the mobility of the second active sub-layer 132 .

[0038] In one application scenario, the total thickness of the first active sublayer 131 and the third active sublayer 133 is in the range of 3-10 nm, for example, the total thickness is 3 nm, 5 nm, 8 nm or 10 nm.

[0039] In an application scenario, the thicknesses of the first active sublayer 131 and the third active sublayer 133 are equal or approximately equal.

[0040] In one application scenario, the first active sub-layer 131 and the third active sub-layer 133 are made of the same material.

[0041] Among them, Figure 2 In the thin film transistor 10, a second transition sublayer (not shown) may also be provided between the second active sublayer 132 and the third active sublayer 133. In this case, the mobility of the second transition sublayer increases in the direction away from the first active sublayer 131. For example, in an application scenario, the mobility of the second transition sublayer increases in a step-like manner in the direction away from the first active sublayer 131. The function and formation method of the second transition sublayer are the same as those of the first transition sublayer, and the details can be found in the above-mentioned related contents, which will not be described in detail here.

[0042] See also Figure 3 ,and Figure 1 and Figure 2 The difference is that the substrate 101 is arranged on the side of the active layer 130 away from the first gate 110. Figure 3 The thin film transistor 10 in the embodiment may also be referred to as a top-gate thin film transistor.

[0043] Continue reading Figure 3 At this time, the active layer 130 further includes a fourth active sublayer 134 , which is located on the side of the first active sublayer 131 close to the first gate 110 , and the mobility of the fourth active sublayer 134 is less than the mobility of the first active sublayer 131 .

[0044] At this time, a fourth active sublayer 134 with lower mobility is arranged on the side of the first active sublayer 131 close to the first gate 110. On the one hand, the fourth active sublayer 134 with low mobility is used to protect the first active sublayer 131 with high mobility to prevent the first active sublayer 131 with high mobility from being disturbed by plasma during the preparation process. On the other hand, compared with the first active sublayer 131 with high mobility being closer to the source 1301 and the drain 1302, the fourth active sublayer 134 with low mobility is arranged closer to the source 1301 and the drain 1302, which can also reduce leakage current.

[0045] That is to say, Figure 3 In the thin film transistor 10, the second active sublayer 132 is used to improve the stability of the thin film transistor 10, and the fourth active sublayer 134 is used to protect the first active sublayer 131 on the one hand and reduce the leakage current of the thin film transistor 10 on the other hand.

[0046] It should be noted that in other implementations, the fourth active sub-layer 134 may not be provided.

[0047] The mobility of the fourth active sub-layer 134 and the second active sub-layer 132 may be equal or different, as long as they are both lower than the mobility of the second active sub-layer 132 .

[0048] In one application scenario, the total thickness of the fourth active sublayer 134 and the second active sublayer 132 is in the range of 10-50 nm, for example, the total thickness is 10 nm, 20 nm, 30 nm or 50 nm.

[0049] In one application scenario, the thickness of the fourth active sublayer 134 is less than that of the second active sublayer 132. In order to avoid reducing the stability of the thin film transistor 10, the thickness of the fourth active sublayer 134 is set to be less than that of the second active sublayer 132. Of course, in other application scenarios, the thickness of the fourth active sublayer 134 may also be equal to the thickness of the second active sublayer 132.

[0050] In one application scenario, in order to reduce the types of materials used, the fourth active sublayer 134 and the second active sublayer 132 are made of the same material.

[0051] Continue reading Figure 3 At this time, the thin film transistor 10 further includes a buffer layer 160 disposed between the active layer 130 and the base substrate 101 . The buffer layer 160 can alleviate the lattice mismatch between the base substrate 101 and the active layer 130 .

[0052] Among them Figure 3In the thin film transistor 10, a third transition sublayer is further included between the first active sublayer 131 and the fourth active sublayer 134, and the mobility of the fourth active sublayer 134 gradually decreases in a direction away from the first active sublayer 131. In an application scenario, the mobility of the fourth active sublayer 134 decreases in a step-like manner in a direction away from the first active sublayer 131.

[0053] Among them, the function and formation method of the third transition sublayer are the same as those of the first transition sublayer. For details, please refer to the above related content and will not be repeated here.

[0054] See also Figure 4 The present application also includes a display panel 20, which includes the thin film transistor 10 in any of the above embodiments. The specific structure of the thin film transistor 10 can be found in the above content and will not be repeated here.

[0055] The display panel 20 may be an LCD display panel (Liquid Crystal Display), an OLED display panel (Organic Light-Emitting Diode), or a Micro-LED display panel (Micro Light Emitting Diode). In short, the present application does not limit the specific structure of the display panel.

[0056] Combine the following Figure 1 , a method for preparing the thin film transistor 10 is introduced, and the method for preparing the thin film transistor 10 includes:

[0057] S110 : forming a first gate electrode 110 , a first insulating layer 120 and an active layer 130 .

[0058] Among them, the first gate 110, the first insulating layer 120 and the active layer 130 are stacked in sequence, and the material of the active layer 130 includes oxide. At the same time, the active layer 130 includes a first active sublayer 131 and a second active sublayer 132 which are stacked in sequence in a direction away from the first gate 110. The mobility of the first active sublayer 131 is higher than the mobility of the second active sublayer 132, and the active layer 130 is prepared by a continuous film forming process.

[0059] The present application does not limit the order in which the first gate 110, the first insulating layer 120, and the active layer 130 are formed. Figure 1 In the bottom gate structure shown in FIG. 1 , a first gate electrode 110 is first formed on one side of the substrate 101, and then a first insulating layer 120 and an active layer 130 are sequentially formed on the side of the first gate electrode 110 away from the substrate 101; when the thin film transistor 10 is Figure 3 In the top gate structure shown, an active layer 130 is first formed on one side of the base substrate 101 , and then a first insulating layer 120 and a first gate 110 are sequentially formed on the side of the active layer 130 away from the base substrate 101 .

[0060] When forming the active layer 130 , the first active sub-layer 131 may be formed first, or the second active sub-layer 132 may be formed first, which is not limited here.

[0061] In this embodiment, the active layer 130 is prepared by a continuous film forming process, and there is no obvious film layer interface in the active layer 130, that is, in the thickness direction, the active layer 130 is a continuous film layer, thereby avoiding interface defects and interface barriers in the stacked structure from affecting the device performance of the thin film transistor.

[0062] In one application scenario, the active layer 130 is continuously formed by a magnetron sputtering deposition process, wherein when the first active sublayer 131 is formed, the ratio of oxygen to argon is within a first preset range, and when the second active sublayer 132 is formed, the ratio of oxygen to argon is within a second preset range, wherein the first preset range is smaller than the second preset range.

[0063] In an application scenario, the first preset range is 2% to 15%, and the second preset range is 20% to 80%. Of course, the first preset range and the second preset range can also be other ranges, which can be set according to actual needs.

[0064] Specifically, in this application scenario, the active layer 130 is formed by a magnetron sputtering deposition process. For the sake of convenience, the following is an example of first forming the first active sub-layer 131 and then forming the second active sub-layer 132:

[0065] When the first active sublayer 131 is formed by a magnetron sputtering deposition process, the ratio of oxygen to argon is controlled to be within a first preset range, for example, the ratio of oxygen to argon is controlled to be about 10%. When the first active sublayer 131 is deposited, the thickness of the first active sublayer 131 can be controlled to be 3 to 10 nm.

[0066] After the first active sublayer 131 is deposited, the second active sublayer 132 is formed. The process does not stop between the deposition of the first active sublayer 131 and the deposition of the second active sublayer 132, specifically, the process actions such as the power supply and the movement of the magnet do not stop, that is, the film deposition is not interrupted, and then the ratio of oxygen to argon is changed so that the ratio is within a second preset range, and then the second active sublayer 132 is deposited. For example, the ratio of oxygen to argon is controlled to be between 20% and 80%, and then the second active sublayer 132 is deposited.

[0067] Wherein, between the deposition of the first active sublayer 131 and the second active sublayer 132, when changing the ratio of oxygen to argon, the ratio of oxygen to argon can be made to directly reach the second preset range. At this time, after the first active sublayer 131 is deposited, the second active sublayer 132 is directly deposited. Alternatively, the ratio of oxygen to argon can be gradually changed, wherein the first transition layer will be deposited and formed in the process of gradually changing the ratio of oxygen to argon. The ratio of oxygen to argon can be changed in steps, or in a straight line. When the ratio of oxygen to argon is changed in steps, the mobility of the deposited first transition layer also changes in steps, and when the ratio of oxygen to argon is changed in a straight line, the mobility of the deposited first transition layer also changes in a straight line.

[0068] In the above application scenario, by changing the ratio of oxygen to argon, the mobility of the first active sublayer 131 is higher than the mobility of the second active sublayer 132. However, in other application scenarios, the ratio of oxygen to argon during the deposition process may not be changed, but other gases such as N2 may be added during the deposition process to change the film structure components, thereby optimizing the bonding stability, so that the mobility of the first active sublayer 131 is higher than the mobility of the second active sublayer 132.

[0069] In another application scenario, co-sputtering can also be used to continuously form the active layer 130 . In this case, the sputtering power, sputtering time and other parameters of different target materials can be controlled so that the mobility of the first active sublayer 131 is greater than the mobility of the second active sublayer 132 .

[0070] For example, when forming the first active sublayer 131, the sputtering power of the first target is controlled to be within the third preset range, and the sputtering power of the second target is controlled to be within the fourth preset range. When forming the second active sublayer 132, the sputtering power of the first target is controlled to be within the fifth preset range, and the sputtering power of the second target is controlled to be within the sixth preset range, wherein the third preset range is greater than the fifth preset range, and the fourth preset range is less than the sixth preset range. At this time, when forming the first active sublayer 131, a first target with high sputtering power is used in combination with a second target with low sputtering power, and then the sputtering power of the first target is reduced, and the sputtering power of the second target is increased to prepare the second active sublayer 132.

[0071] In one application scenario, the material of the first target includes indium oxide, and the material of the second target includes gallium oxide. At this time, when forming the first active sublayer 131, indium oxide with high sputtering power is used in combination with gallium oxide with low sputtering power, and then the sputtering power of indium oxide is reduced and the sputtering power of gallium oxide is increased to prepare the second active sublayer 132.

[0072] When the sputtering power of the first target material and the second target material is changed, the change may be gradual or abrupt. It is understandable that when the change is gradual, a first transition sublayer will be formed between the first active sublayer 131 and the second active sublayer 132 .

[0073] The above are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A thin film transistor, characterized in that: The thin film transistor comprises: a first gate; A first insulating layer, located on one side of the first gate; An active layer is arranged on the side of the first insulating layer away from the first gate, wherein the active layer is a continuous film layer in the thickness direction and the material of the active layer includes oxide, and the active layer includes a first active sublayer and a second active sublayer stacked in sequence in a direction away from the first gate, and the mobility of the first active sublayer is higher than the mobility of the second active sublayer.

2. The thin film transistor according to claim 1, characterized in that: The thickness of the first active sublayer is smaller than the thickness of the second active sublayer; Preferably, the thickness of the first active sublayer is in the range of 3-10 nm; Preferably, the thickness of the second active sublayer is in the range of 10-50 nm; Preferably, the first active sublayer and the second active sublayer are made of the same material.

3. The thin film transistor according to claim 1, characterized in that: The active layer further includes a first transition sublayer located between the first active sublayer and the second active sublayer, wherein the mobility of the first transition sublayer gradually decreases in a direction away from the first gate; Preferably, in a direction away from the first gate, the mobility of the first transition sublayer decreases in a step-like manner; Preferably, the thickness of the first transition sublayer is less than or equal to 3 nm.

4. The thin film transistor according to claim 1, characterized in that: It also includes a substrate, which is arranged on a side of the first gate away from the first insulating layer.

5. The thin film transistor according to claim 4, characterized in that: The thin film transistor further comprises: A second insulating layer is disposed on a side of the active layer away from the first gate; A second gate is arranged on a side of the second insulating layer away from the first gate; Wherein, the active layer further comprises a third active sublayer, the third active sublayer is located on a side of the second active sublayer away from the first active sublayer, wherein the mobility of the third active sublayer is higher than the mobility of the second active sublayer; Preferably, the mobility of the first active sublayer and the third active sublayer is equal; Preferably, the total thickness of the first active sublayer and the third active sublayer is in the range of 3-10 nm; Preferably, the first active sublayer and the third active sublayer have the same thickness; Preferably, the first active sublayer and the third active sublayer are made of the same material.

6. The thin film transistor according to claim 1, characterized in that: It also includes a substrate, which is arranged on a side of the active layer away from the first gate; Preferably, the active layer further comprises a fourth active sublayer, the fourth active sublayer is located on a side of the first active sublayer close to the first gate, and the mobility of the fourth active sublayer is smaller than the mobility of the first active sublayer; Preferably, the mobility of the fourth active sublayer and the second active sublayer is equal; Preferably, the total thickness of the fourth active sublayer and the second active sublayer is in the range of 10-50 nm; Preferably, the thickness of the fourth active sublayer is less than the thickness of the second active sublayer; Preferably, the fourth active sublayer and the second active sublayer are made of the same material.

7. A display panel, characterized in that: Comprising the thin film transistor according to any one of claims 1 to 6.

8. A method for preparing a thin film transistor, characterized in that: The method comprises: forming a first gate, a first insulating layer and an active layer; Among them, the first gate, the first insulating layer and the active layer are stacked in sequence, and the material of the active layer includes oxide. At the same time, the active layer includes a first active sublayer and a second active sublayer stacked in sequence in a direction away from the first gate. The mobility of the first active sublayer is higher than the mobility of the second active sublayer, and the active layer is prepared by a continuous film forming process.

9. The method according to claim 8, characterized in that The step of preparing the active layer by a continuous film forming process comprises: The active layer is continuously formed by a magnetron sputtering deposition process, wherein when forming the first active sublayer, the ratio of oxygen to argon is within a first preset range, and when forming the second active sublayer, the ratio of oxygen to argon is within a second preset range, wherein the first preset range is smaller than the second preset range; Preferably, the first preset range is 2% to 15%; Preferably, the second preset range is 20% to 80%; Preferably, after forming the first active sublayer, the ratio of oxygen to argon is gradually changed until the ratio of oxygen to argon is within the second preset range.

10. The method according to claim 8, characterized in that The step of preparing the active layer by a continuous film forming process comprises: The active layer is continuously formed by a co-sputtering process, wherein when forming the first active sub-layer, the sputtering power of the first target material is controlled to be within a third preset range, and the sputtering power of the second target material is controlled to be within a fourth preset range, and when forming the second active sub-layer, the sputtering power of the first target material is controlled to be within a fifth preset range, and the sputtering power of the second target material is controlled to be within a sixth preset range, wherein the third preset range is greater than the fifth preset range, and the fourth preset range is less than the sixth preset range; Preferably, the material of the first target includes indium oxide, and the material of the second target includes gallium oxide.

Images