Method for roughening surface of ito and led chip

Abstract

The application discloses an ITO surface roughening treatment method, comprising the following steps: preparing a GaN wafer, wherein the surface of the GaN wafer is covered with an ITO film layer; performing ion beam bombardment on the ITO film layer by using a preset ion dose of a low-energy ion beam, and meanwhile, the GaN wafer is self-rotated at a preset speed, so that a regularly arranged point structure of nanometer size is formed on the surface of the ITO film layer, and an ITO film layer after surface roughening is obtained. The application has the advantages of simple operation, low cost, high production efficiency, and the like, and can effectively improve the external quantum efficiency of an LED chip and improve the light-emitting brightness of the LED.

Description

Technical Field

[0001] This invention relates to the field of light-emitting diode chip technology, and in particular to an ITO surface roughening treatment method and an LED chip. Background Technology

[0002] In recent years, with the great progress made in P-type gallium nitride doping technology, gallium nitride-based LEDs, which have excellent characteristics such as fast response, long life, low power consumption, small size and high brightness, have been widely used in backlights for liquid crystal displays, full-color displays, traffic displays and other applications.

[0003] Light extraction efficiency has always been a major technical challenge hindering the development of gallium nitride (GaN)-based LEDs. Currently, the light extraction efficiency depends on both internal quantum efficiency and light extraction efficiency. While internal quantum efficiency has been maximized, the significant difference in refraction between the surface material and air easily leads to total emission at the interface, resulting in a lower external quantum efficiency. Therefore, external quantum efficiency still needs further improvement. In recent years, some methods have emerged to improve external quantum efficiency by altering surface roughness through post-processing techniques. The principle is to increase the number of light selection opportunities by adding a rough structure, effectively changing the light path and increasing the probability of emission. However, current roughening methods mostly involve wet etching, which is complex, cumbersome, and costly. Moreover, it suffers from poor etching stability, requires strict control over the concentration of the etching solution, and makes it difficult to create a single roughened structure. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an ITO surface roughening treatment method that is simple to operate, low in cost, and high in production efficiency, and can effectively improve the external quantum efficiency of LED chips.

[0005] The technical problem to be solved by the present invention is to provide an LED chip that uses a specific ITO surface roughening treatment method to roughen the ITO surface, which can effectively improve the LED luminous brightness.

[0006] To address the aforementioned technical problems, this invention provides a method for roughening the surface of ITO, comprising the following steps:

[0007] S1. Prepare a GaN epitaxial wafer, the surface of which is covered with an ITO thin film layer;

[0008] S2. The ITO thin film layer is bombarded with a low-energy ion beam with a preset irradiation dose, while the GaN epitaxial wafer rotates at a preset rate to form a regularly arranged nano-sized dot structure on the surface of the ITO thin film layer, thereby obtaining a roughened ITO thin film layer.

[0009] In one embodiment, the process further includes annealing the roughened ITO thin film layer.

[0010] In one embodiment, the preset irradiation dose of the low-energy ion beam is ≥1*10-1 16 uA / cm 2 ;

[0011] The preset rotation rate of the GaN epitaxial wafer is ≥10 r / min.

[0012] Preferably, the preset irradiation dose of the low-energy ion beam is 1*10-1. 16 uA / cm 2 ~1*10 17 uA / cm 2 ;

[0013] The preset rotation rate of the GaN epitaxial wafer is 10 r / min to 30 r / min.

[0014] In one embodiment, the beam current density of the low-energy ion beam is 10 μA / cm². 2 ~10000uA / cm 2 ;

[0015] The energy of the low-energy ion beam is ≤1000eV;

[0016] The vertical deviation of the low-energy ion beam is ≤5°;

[0017] The angle between the low-energy ion beam and the normal to the surface of the ITO thin film is 0° to 75°.

[0018] Preferably, the beam current density of the low-energy ion beam is 15 μA / cm. 2 ~100uAcm 2 ;

[0019] The energy of the low-energy ion beam is 300eV to 600eV;

[0020] The vertical deviation of the low-energy ion beam is ≤4°;

[0021] The angle between the low-energy ion beam and the normal to the surface of the ITO thin film is 0° to 45°.

[0022] In one embodiment, the surface roughened ITO thin film layer

[0023] In one embodiment, before bombarding the ITO thin film layer with an ion beam, the GaN epitaxial wafer with the ITO thin film layer on its surface is further subjected to an annealing process.

[0024] In one embodiment, the annealing process is rapid thermal annealing, with an annealing temperature of 500°C to 600°C.

[0025] To address the aforementioned problems, the present invention also provides an LED chip, the LED chip comprising an ITO thin film layer, wherein the ITO thin film layer is subjected to surface roughening treatment using the aforementioned ITO surface roughening treatment method.

[0026] Implementing this invention has the following beneficial effects:

[0027] The ITO surface roughening method provided by this invention can achieve periodic roughening of a large area of ​​ITO surface. It uses ion beam bombardment technology combined with the rotation of the roughened ITO thin film layer to induce the ITO thin film layer to obtain a periodic self-organized nano-dot structure through a combination of ion erosion, atomic rearrangement and relaxation mechanisms. The regularly arranged dot structure can effectively improve the external quantum efficiency, thereby improving the luminous brightness of LED. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the surface of an ITO thin film layer obtained after processing according to the ITO surface roughening method provided by the present invention.

[0029] Figure 2 IV characteristic test diagrams of LED chips made from GaN epitaxial wafers processed according to Examples 1-3 and Comparative Example 1 of the present invention;

[0030] Figure 3 These are test images of the PI characteristics of LED chips made from GaN epitaxial wafers processed according to Examples 1-3 and Comparative Example 1 of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0032] the term

[0033] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0034] In this invention, the terms "combinations thereof", "any combination thereof", and "any combination thereof" include all suitable combinations of any two or more items listed.

[0035] In this invention, "preferred" is merely a description of a more effective implementation method or embodiment, and should be understood as not constituting a limitation on the scope of protection of this invention.

[0036] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0037] In this invention, numerical ranges are involved, and unless otherwise specified, they include the two endpoints of the numerical range.

[0038] This invention provides a method for roughening the surface of ITO, comprising the following steps:

[0039] S1. Prepare a GaN epitaxial wafer, the surface of which is covered with an ITO thin film layer;

[0040] The GaN epitaxial wafer is prepared using conventional methods, including but not limited to MSA and CBL fabrication methods.

[0041] S2. The ITO thin film layer is bombarded with a low-energy ion beam with a preset irradiation dose, while the GaN epitaxial wafer rotates at a preset rate to form a regularly arranged nano-sized dot structure on the surface of the ITO thin film layer, thereby obtaining a roughened ITO thin film layer.

[0042] The ITO surface roughening method provided by this invention can achieve periodic roughening of a large area of ​​ITO surface. It uses ion beam bombardment technology combined with the rotation of the roughened ITO thin film layer to induce the ITO thin film layer to obtain a periodic self-organized nano-dot structure through a combination of ion erosion, atomic rearrangement and relaxation mechanisms. The regularly arranged dot structure can effectively improve the external quantum efficiency, thereby improving the luminous brightness of LED.

[0043] It should be noted that this invention is the result of the combined effects of ion erosion, atomic rearrangement, and relaxation mechanisms. Otherwise, under low-energy ion beam bombardment, only ion cleaning of the ITO thin film surface can be achieved, without generating periodic nanostructures. Through numerous creative experiments, the inventors discovered that by controlling the irradiation dose of the low-energy ion beam and combining it with the self-rotation of the coarsened ITO thin film, it is possible to achieve the combined effects of ion erosion, atomic rearrangement, and relaxation mechanisms, ultimately obtaining regularly arranged nanoscale point structures. These regularly arranged nanoscale point structures are self-organized and include nanodots, nanopores, and nanoripples. By changing the parameters of the low-energy ion beam, a nanostructure array with controllable size and order can be induced on the ITO thin film surface within a short processing time. This enables the fabrication of large-area controllable nanostructures under maskless conditions, offering advantages such as low cost, high efficiency, and wide applicability.

[0044] In one embodiment, the preset irradiation dose of the low-energy ion beam is ≥1*10-1 16 uA / cm 2The preset rotation rate of the GaN epitaxial wafer is ≥10 r / min. If the preset irradiation dose of the low-energy ion beam is too low, stable perturbation cannot be achieved, thus preventing the combined action of ion etching, atomic rearrangement, and relaxation mechanisms, and consequently, the formation of regularly arranged nanoscale dot structures. The rotation of the GaN epitaxial wafer drives the rotation of the roughened ITO thin film layer. If the preset rotation rate of the GaN epitaxial wafer is too low, no obvious dot-like nanostructures will be generated. However, if the preset irradiation dose of the low-energy ion beam is too high, the required time is too long, affecting productivity; if the preset rotation rate of the GaN epitaxial wafer is too fast, the dot structure will be too dense, failing to perfectly reflect the surface roughness. Preferably, the preset irradiation dose of the low-energy ion beam is 1*10. 16 uA / cm 2 ~1*10 17 uA / cm 2 The preset rotation speed of the GaN epitaxial wafer is 10 r / min to 30 r / min.

[0045] In one embodiment, the beam current density of the low-energy ion beam is 10 μA / cm². 2 ~1000uA / cm 2 The beam current density of the low-energy ion beam directly affects the irradiation dose. If the beam current density is too low, the roughening time will be prolonged, affecting production capacity; if the beam current density is too high, the energy generated by collisions cannot be quickly discharged, causing the chip temperature to rise excessively and affecting structural performance. Preferably, the beam current density of the low-energy ion beam is 15 μA / cm. 2 ~100uAcm 2 .

[0046] In one embodiment, the energy of the low-energy ion beam is ≤1000 eV. The energy of the low-energy ion beam affects the depth of the roughened structure on the surface of the ITO thin film layer. If the energy of the low-energy ion beam is too low, the effect of improving the external quantum efficiency will be insignificant; if the energy of the low-energy ion beam is too high, it will cause severe lattice damage to the surface of the ITO thin film layer, thereby increasing the resistivity of the ITO thin film layer. Preferably, the energy of the low-energy ion beam is 300 eV to 600 eV.

[0047] The low-energy ion beam bombardment described in this invention can be performed in a high-vacuum sputtering chamber or an implanter. High beam collimation is required during the roughening process. In one embodiment, the vertical deviation of the low-energy ion beam is ≤5°; preferably, the vertical deviation is ≤4°. This ensures the formation of regularly arranged nanoscale point structures. Furthermore, in one embodiment, the angle between the low-energy ion beam and the normal to the surface of the ITO thin film is 0°–75°. Preferably, the angle between the low-energy ion beam and the normal to the surface of the ITO thin film is 0°–45°.

[0048] Based on the above parameters, we can obtain the following: Figure 1 The regularly arranged nanoscale dot structures shown are not limited to the parameters listed above. Different shapes of nanoscale dot structures can be obtained by changing the ion beam energy, irradiation angle, beam current density, irradiation dose, and rotation speed. The size and spacing of the nanoscale dot structures vary.

[0049] In one embodiment, before bombarding the ITO thin film layer with an ion beam, the GaN epitaxial wafer with the ITO thin film layer on its surface is further subjected to annealing. In one embodiment, after bombarding the ITO thin film layer with an ion beam, the surface-roughened ITO thin film layer is further subjected to annealing. Annealing the ITO thin film layer before ion beam bombardment helps to make the surface of the ITO thin film layer smoother, which is beneficial for subsequent low-energy ion beam bombardment, and can also reduce the resistivity and increase the transmittance of the ITO thin film layer. Secondary annealing after ion beam bombardment can release residual gas in the shallow layer and relieve stress, while repairing excess lattice damage caused by bombardment, thereby maximizing the LED's luminous brightness. In one embodiment, the surface-roughened ITO thin film layer... In one embodiment, the annealing process is rapid thermal annealing, with an annealing temperature of 500°C to 600°C.

[0050] Accordingly, the present invention also provides an LED chip, the LED chip including an ITO thin film layer, the ITO thin film layer being surface roughened using the above-described ITO surface roughening treatment method.

[0051] In summary, this invention utilizes low-energy ion beam induction technology to prepare large-area periodic nanodot structures on ITO surfaces. These periodic surface nanostructures possess excellent optical properties, such as antireflection, antireflection, and polarization, which can improve light emission probability and thus enhance external quantum efficiency. Compared to existing wet etching methods for achieving surface roughening structures, this invention is simpler, lower in cost, and faster.

[0052] The present invention is further illustrated below with specific embodiments:

[0053] Example 1

[0054] This embodiment provides a method for roughening the surface of ITO, including the following steps:

[0055] S1. Prepare a GaN epitaxial wafer, the surface of which is covered with a coating of thickness [thickness missing]. The ITO thin film layer is then annealed at 550°C.

[0056] S2. The ITO thin film layer is bombarded with a low-energy ion beam with a preset irradiation dose, while the GaN epitaxial wafer rotates at a preset rate to form a regularly arranged nano-sized dot structure on the surface of the ITO thin film layer, thereby obtaining an ITO thin film layer with roughened surface.

[0057] The preset irradiation dose of the low-energy ion beam is 1*10. 16 uA / cm 2 The preset rotation rate of the GaN epitaxial wafer is 10 r / min; the beam current density of the low-energy ion beam is 30 μA / cm. 2 The energy of the low-energy ion beam is 500 eV; the vertical deviation of the low-energy ion beam is 5°; the angle between the low-energy ion beam and the normal to the surface of the ITO thin film is 0°; after bombardment, a secondary annealing treatment is performed at 550°C.

[0058] Example 2

[0059] This embodiment provides a method for roughening the surface of ITO, including the following steps:

[0060] S1. Prepare a GaN epitaxial wafer, the surface of which is covered with a coating of thickness [thickness missing]. The ITO thin film layer is then annealed at 550°C.

[0061] S2. The ITO thin film layer is bombarded with a low-energy ion beam with a preset irradiation dose, while the GaN epitaxial wafer rotates at a preset rate to form a regularly arranged nano-sized dot structure on the surface of the ITO thin film layer, thereby obtaining an ITO thin film layer with roughened surface.

[0062] The preset irradiation dose of the low-energy ion beam is 1*10. 17 uA / cm 2 The preset rotation speed of the GaN epitaxial wafer is 30 r / min; the beam current density of the low-energy ion beam is 100 μA / cm. 2The energy of the low-energy ion beam is 1000 eV; the vertical deviation of the low-energy ion beam is 4°; the angle between the low-energy ion beam and the normal to the surface of the ITO thin film is 60°; after bombardment, a secondary annealing treatment is performed at 550°C.

[0063] Example 3

[0064] This embodiment provides a method for roughening the surface of ITO, including the following steps:

[0065] S1. Prepare a GaN epitaxial wafer, the surface of which is covered with a coating of thickness [thickness missing]. The ITO thin film layer is then annealed at 550°C.

[0066] S2. The ITO thin film layer is bombarded with a low-energy ion beam with a preset irradiation dose, while the GaN epitaxial wafer rotates at a preset rate to form a regularly arranged nano-sized dot structure on the surface of the ITO thin film layer, thereby obtaining an ITO thin film layer with roughened surface.

[0067] The preset irradiation dose of the low-energy ion beam is 1*10. 18 uA / cm 2 The preset rotation rate of the GaN epitaxial wafer is 50 r / min; the beam current density of the low-energy ion beam is 1000 μA / cm. 2 The energy of the low-energy ion beam is 600 eV; the vertical deviation of the low-energy ion beam is 4°; the angle between the low-energy ion beam and the normal to the surface of the ITO thin film is 45°; after bombardment, a secondary annealing treatment is performed at 550°C.

[0068] Comparative Example 1

[0069] This embodiment provides a comparative method for smoothing the surface of ITO, including the following steps:

[0070] S1. Prepare a GaN epitaxial wafer, the surface of which is covered with a coating of thickness [thickness missing]. The ITO thin film layer is then annealed at 550°C.

[0071] S2. Without surface roughening treatment, a relatively smooth ITO thin film layer is obtained.

[0072] The GaN epitaxial wafers processed in Examples 1-3 and Comparative Example 1 were fabricated into LED chips, and the IV and PI characteristics of the devices were tested, yielding the following results: Figure 2 , 3 The comparison curves of current-voltage relationship and luminous intensity are shown. From... Figure 2As can be seen, the current-voltage relationship curves of the LED chips prepared in Examples 1-3 and the LED chip prepared in Comparative Example 1 almost overlap, indicating that the ITO surface roughening treatment method provided by the present invention does not increase the voltage of the LED. In other words, the ITO surface roughening treatment method provided by the present invention does not bring about an additional increase in resistance.

[0073] from Figure 3 As can be seen, the light power of the LED chips prepared in Examples 1 to 3 is significantly higher than that of the LED chip prepared in Comparative Example 1, indicating that the ITO surface roughening treatment method provided by the present invention can effectively improve the light brightness of LEDs.

[0074] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A method for roughening an ITO surface, characterized by, The method comprises the following steps: preparing a GaN wafer, the surface of which is covered with an ITO film layer; performing ion beam bombardment on the ITO film layer with a preset dosage of low-energy ion beam, while the GaN wafer rotates at a preset speed, so that the surface of the ITO film layer forms regularly arranged nano-sized dot structures, thereby obtaining a surface-roughened ITO film layer; The preset irradiation dose of the low-energy ion beam is 1*10 16 uA / cm 2 ~1*10 17 uA / cm 2 ; the preset speed of the GaN wafer during rotation is 10 r / min to 30 r / min.

2. The ITO surface roughening process of claim 1, wherein, The method further comprises annealing the surface-roughened ITO film layer.

3. The ITO surface roughening process of claim 1, wherein, The low-energy ion beam has a beam current density of 10 uA / cm 2 ~10000 uA / cm 2 ; The energy of the low-energy ion beam is ≤1000 eV; the up-and-down deviation of the low-energy ion beam is ≤5°; the angle between the low-energy ion beam and the normal of the surface of the ITO film layer is 0° to 75°.

4. The ITO surface roughening process of claim 3, wherein, The low-energy ion beam has a beam current density of 15 uA / cm 2 100 uA / cm 2 ; The energy of the low-energy ion beam is 300 eV to 600 eV; the up-and-down deviation of the low-energy ion beam is ≤4°; the angle between the low-energy ion beam and the normal of the surface of the ITO film layer is 0° to 45°.

5. The ITO surface roughening process of claim 1 wherein, The average thickness of the surface-roughened ITO film layer is ≥600 Å.

6. The ITO surface roughening process of claim 1 wherein, Before performing ion beam bombardment on the ITO film layer, the method further comprises annealing the GaN wafer, the surface of which is covered with the ITO film layer.

7. The ITO surface roughening process of claim 2 or 6, wherein The annealing is rapid thermal annealing, and the annealing temperature is 500 ℃ to 600 ℃.

8. An LED chip, characterized by The LED chip comprises an ITO film layer, and the ITO film layer is surface-roughened by the ITO surface-roughening method according to any one of claims 1 to 7.

Images