A method for controlling the breakdown voltage of a SiC APD linear array

Abstract

The application discloses a kind of SiC APD linear array breakdown voltage regulation method, this method is by setting breakdown voltage, the fluctuation value ΔV of the average breakdown voltage between each pixel is obtained B , the breakdown voltage is sequentially grouped according to from big to small order to the whole SiC APD linear array, the breakdown voltage of each pixel is regulated by the upper electrode of each pixel, and the voltage value higher than the average voltage V B1 Is selected as the working voltage of SiC APD linear array, and the working voltage is applied to the back electrode commonly used to SiC APD linear array, so that SiC APD linear array carries out ultraviolet detection imaging.The breakdown voltage of each pixel is regulated in the application, so that each pixel can work under the same gain and detection energy, and high-quality ultraviolet detection imaging is obtained.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology for semiconductor devices, and in particular to a method for controlling the breakdown voltage of a SiC APD linear array. Background Technology

[0002] An avalanche photodiode (APD) is a photosensitive element used in laser communication. When a reverse bias voltage is applied to the PN junction of a photodiode made of silicon or germanium, incident light is absorbed by the PN junction, forming a photocurrent. Increasing the reverse bias voltage causes an "avalanche" phenomenon (i.e., a dramatic increase in photocurrent), hence the name "avalanche photodiode."

[0003] SiC APDs, as weak ultraviolet light detection devices, have important applications in fire early warning, high-voltage power grid corona detection, national defense early warning, space exploration, and other fields of public welfare, military, and scientific research. Currently, individual SiC APD devices already possess relatively excellent single-photon detection performance. To achieve ultraviolet detection imaging, SiC APD devices are evolving from single devices to focal plane arrays, and 1×128 SiC APD linear arrays have already been successfully fabricated. Because SiC APD devices operate in avalanche breakdown state during weak light detection, even small fluctuations in breakdown voltage between SiC APD devices can cause significant differences in gain and detection efficiency, hindering the realization of ultraviolet detection imaging. Therefore, pixels in the imaging array need to have high breakdown voltage uniformity. However, even small differences in the thickness of the multiplication layer and the doping concentration during the SiC epitaxy process can lead to fluctuations in the device's breakdown voltage.

[0004] Therefore, how to improve the fluctuation of pixel breakdown voltage in SiC APD linear array and ensure the quality of ultraviolet detection imaging is a technical problem that needs to be solved in this field. Summary of the Invention

[0005] This invention provides a method for controlling the breakdown voltage of a SiC APD linear array. By controlling the breakdown voltage of each pixel, each pixel in the linear array operates at the same gain level, resulting in uniform and stable breakdown voltage fluctuations and high-quality ultraviolet detection imaging.

[0006] To achieve the above effects, the technical solution of the present invention is as follows:

[0007] A method for controlling the breakdown voltage of a SiC APD linear array includes the following steps:

[0008] S1: Select x pixels at both ends of the SiC APD linear array, measure and obtain the current-voltage curve of each pixel, set the breakdown voltage, and take the average value of the voltages of the x pixels as the average voltage. The average voltages at both ends of the SiC APD linear array are respectively the average voltage V. B1 Average voltage V B2 ;

[0009] S2: Based on average voltage V B1 Average voltage V B2 The fluctuation value ΔV of the average breakdown voltage between each pixel is obtained. B ;

[0010] S3: Based on fluctuation value ΔV B Group the entire SiC APD linear array;

[0011] S4: After the SiC APD linear array is grouped, the breakdown voltage is grouped in descending order;

[0012] S5: After the breakdown voltage is grouped, the breakdown voltage of each pixel is regulated by the independent upper electrode of each pixel.

[0013] S6: Select a voltage higher than the average voltage V B1 The voltage value is used as the working voltage of the SiC APD linear array. The working voltage is applied to the back electrode shared by the SiC APD linear array, enabling the SiC APD linear array to perform ultraviolet detection imaging.

[0014] Furthermore, in step S1, the number of x pixels is 5 pixels.

[0015] Furthermore, in step S1, the breakdown voltage is set by selecting the voltage value at which the current is 10nA as the breakdown voltage.

[0016] Furthermore, step S2 specifically involves: averaging the voltage V... B1 With average voltage V B2 Dividing the difference between the two values ​​by the difference between the total number of pixels in the linear array minus 1 yields the average breakdown voltage fluctuation value ΔV between each pixel. B .

[0017] Furthermore, step S3 specifically involves: using the MV voltage value as the standard for allowable fluctuations in breakdown voltage, grouping the entire SiC APD linear array, and dividing M by the average breakdown voltage fluctuation value ΔV. B The obtained value is rounded down to the nearest integer m, which represents a group of m pixels.

[0018] Furthermore, in step S3, M is set to 0.1.

[0019] Furthermore, in step S4, the breakdown voltages are grouped sequentially in descending order, with the number of groups set to n.

[0020] Furthermore, step S4 specifically involves grouping the breakdown voltages in descending order: the first to the mth pixels form the first group, the (m+1)th to the 2mth pixels form the second group, the (2m+1)th to the 3mth pixels form the third group, and so on, until the number of remaining pixels in the linear array is less than or equal to m, which is the last group, denoted as the nth group.

[0021] Furthermore, the control method in step S5 is as follows: 0V bias voltage is applied to the upper electrode of each pixel in the first group, 0.1V bias voltage is applied to the upper electrode of each pixel in the second group, 0.2V bias voltage is applied to the upper electrode of each pixel in the third group, and so on, and (n-1)×0.1V bias voltage is applied to the upper electrode of each pixel in the last group.

[0022] Furthermore, the SiC APD linear array is a 1×128 SiC APD linear array.

[0023] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0024] This invention can effectively improve the inter-pixel breakdown voltage fluctuation caused by differences in epitaxial layer thickness and doping concentration in SiC APD linear arrays. By grouping and controlling the breakdown voltage of each pixel, each pixel can operate under the same gain and detection capability, resulting in uniform and stable breakdown voltage fluctuations and high-quality ultraviolet detection imaging. In addition, this invention does not require characterizing the current-voltage curves of all pixels in the linear array, resulting in high working efficiency and simple operation. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0026] Figure 1 This is a schematic diagram of the process of an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of multiple 1×128 SiC APD linear arrays under a microscope.

[0028] Figure 3 This is a microscopic illustration of a single SiC APD according to the present invention;

[0029] Figure 4 This is a schematic diagram of the breakdown voltage values ​​of each pixel in a 1×128 SiC APD linear array according to the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] For easier understanding, please refer to Figures 1-4 An embodiment of a method for controlling the breakdown voltage of a SiC APD linear array provided by the present invention includes the following steps:

[0033] S1: Select 5 pixels at the first end of the SiC APD linear array, measure and obtain the current-voltage curve of each pixel, select the voltage value at which the current is 10nA as the breakdown voltage, and take the average value of the voltages of the 5 pixels as the average voltage V. B1 Five pixels at the second end of the SiC APD linear array were selected, and the current-voltage curves of the pixels were measured and obtained. The voltage value at which the current is 10nA was selected as the breakdown voltage, and the average value of the voltages of the five pixels was taken as the average voltage V. B2 ;

[0034] S2: Average voltage V B1 With average voltage V B2 Dividing the difference between the two values ​​by the difference between the total number of pixels in the linear array minus 1 yields the average breakdown voltage fluctuation value ΔV between each pixel. B ;

[0035] S3: Using a voltage value of 0.1V as the standard for allowable fluctuations in breakdown voltage, the entire SiC APD linear array is grouped, and 0.1V is divided by the average breakdown voltage fluctuation value ΔV. B The obtained value is rounded down to the nearest integer m, which means that m pixels are grouped together.

[0036] S4: Group the breakdown voltages in descending order. The first to the mth pixels are the first group, the (m+1)th to the 2mth pixels are the second group, the (2m+1)th to the 3mth pixels are the third group, and so on, until the number of remaining pixels in the linear array is less than or equal to m, which is the last group, denoted as the nth group.

[0037] S5: The breakdown voltage of each pixel is controlled by the independent upper electrode 2 of each pixel. In the first group, a 0V bias voltage is applied to the upper electrode 2 of each pixel. In the second group, a 0.1V bias voltage is applied to the upper electrode 2 of each pixel. In the third group, a 0.2V bias voltage is applied to the upper electrode 2 of each pixel. And so on. In the last group, a (n-1)×0.1V bias voltage is applied to the upper electrode 2 of each pixel.

[0038] S6: Select a voltage higher than the average voltage V B1 The voltage value is used as the working voltage of the SiC APD linear array. The working voltage is applied to the back electrode shared by the SiC APD linear array, enabling the SiC APD linear array to perform ultraviolet detection imaging.

[0039] Figure 2 Multiple 1×128 SiC APD linear arrays; Figure 3 It is a single SiC APD, including a device mesa 1 and an upper electrode 2, which are fabricated on a SiC epitaxial layer 3. Figure 4 This indicates that there are fluctuations in the breakdown voltage between different pixels. As can be seen from the figure, the fluctuations are basically linear. Therefore, the method proposed in this invention, which groups the breakdown voltages in descending order and controls the breakdown voltage of each pixel, can be adopted.

[0040] This invention achieves high-quality ultraviolet detection imaging by grouping and controlling the breakdown voltage of each pixel, enabling each pixel in the linear array to operate at the same gain level. In addition, this invention does not require characterizing the current-voltage curves of all pixels in the linear array, resulting in high efficiency and simple operation.

[0041] Example 2

[0042] Specifically, based on Example 1, the solution will be described in conjunction with specific embodiments to further demonstrate its technical effects. Specifically:

[0043] Taking a pin-structured 1×128 SiC APD linear array as an example:

[0044] S1: Select 5 pixels at the first end of the SiC APD linear array, measure and obtain the current-voltage curves of the pixels, and select the voltage value at the current of 10nA as the breakdown voltage. The breakdown voltages of the five pixels are 194.98V, 194.98V, 194.98V, 194.99V and 194.97V respectively, and take the average value of the voltages of the five pixels as the average voltage V. B1 =194.98V;

[0045] Five pixels at the second end of a SiC APD linear array were selected, and their current-voltage curves were measured and obtained. The voltage value at which the current was 10nA was selected as the breakdown voltage. The breakdown voltages of the five pixels were 193.52V, 193.55V, 193.57V, 193.51V, and 193.51V, respectively. The average value of the five pixel voltages was taken as the average voltage V. B2 =193.53V.

[0046] S2: Average voltage V B1 With average voltage V B2 Dividing the difference between the two values ​​by the difference between the total number of pixels in the linear array minus 1 yields the fluctuation value ΔV of the average breakdown voltage between each pixel. B =0.011V;

[0047] S3: Using a voltage value of 0.1V as the standard for allowable fluctuations in breakdown voltage, group the entire SiC APD linear array and divide 0.1V by the average breakdown voltage fluctuation value ΔV. B The obtained value is rounded down to the nearest integer, which is denoted as m. That is, 9 pixels form a group;

[0048] S4: Group the breakdown voltages in descending order. Pixels 1-9 form the first group, pixels 10-18 the second, pixels 19-27 the third, pixels 28-36 the fourth, pixels 37-45 the fifth, pixels 46-54 the sixth, pixels 55-63 the seventh, and the 64th... The 72nd pixel is the eighth group, the 73rd to 81st pixels are the ninth group, the 82nd to 90th pixels are the tenth group, the 91st to 99th pixels are the eleventh group, the 100th to 108th pixels are the twelfth group, the 109th to 117th pixels are the thirteenth group, the 118th to 126th pixels are the fourteenth group, and the 127th to 128th pixels are the fifteenth group.

[0049] S5: The breakdown voltage of each pixel is controlled by the independent upper electrode 2 of each pixel. In the first group, a 0V bias voltage is applied to the upper electrode 2 of each pixel. In the second group, a 0.1V bias voltage is applied to the upper electrode 2 of each pixel. In the third group, a 0.2V bias voltage is applied to the upper electrode 2 of each pixel. And so on. In the fifteenth group, a 1.4V bias voltage is applied to the upper electrode 2 of each pixel.

[0050] S6: Select a voltage higher than the average voltage V B1The voltage value is used as the working voltage of the SiC APD linear array, such as 198V, and is applied to the back electrode shared by the SiC APD linear array, so that the SiC APD linear array works in the avalanche breakdown state for ultraviolet detection and imaging.

[0051] The above method can smooth out the breakdown voltage fluctuations among the 128 pixels in the linear array. When the SiC APD linear array is working, it can ensure the uniformity of gain among each pixel point, thereby obtaining high-quality ultraviolet detection imaging.

[0052] In practical implementation, by comparing the pixel breakdown voltage in the SiC APD linear array with the applied bias voltage after modulation, the absolute error value of the pixel breakdown voltage before modulation reaches 1.5V. After modulation by the method of this invention, the absolute error value of the over-bias voltage of the pixel is controlled at 0.2V. Under this condition, the difference in single-photon detection efficiency between pixels can be ignored, which is beneficial to obtaining high-quality ultraviolet imaging.

[0053] It should be noted that the upper electrode 2 can also be understood as the upper anode, and the back electrode can also be understood as the back cathode.

[0054] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0056] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without creative effort.

Claims

1. A method for controlling the breakdown voltage of a SiC APD linear array, characterized in that, Includes the following steps: S1: Select x pixels at both ends of the SiC APD linear array, measure and obtain the current-voltage curve of each pixel, set the breakdown voltage, and take the average value of the voltages of the x pixels as the average voltage. The average voltages at both ends of the SiC APD linear array are respectively the average voltage V. B1 Average voltage V B2 ; S2: Based on average voltage V B1 Average voltage V B2 The fluctuation value of the average breakdown voltage between each pixel is obtained. ; Step S2 specifically involves: averaging the voltage V... B1 With average voltage V B2 Dividing the difference between the values ​​by the difference between the total number of pixels in the linear array minus 1 yields the average breakdown voltage fluctuation value between each pixel. ; S3: Based on fluctuation value Group the entire SiC APD linear array; Step S3 specifically involves: using the MV voltage value as the standard for allowable fluctuations in breakdown voltage, grouping the entire SiC APD linear array, and dividing M by the average breakdown voltage fluctuation value. The obtained value is rounded down to the nearest integer m, which means that m pixels are grouped together. In step S3, M is set to 0.1; S4: After the SiC APD linear array is grouped, the breakdown voltage is grouped in descending order, and the number of groups is set to n. The first to the mth pixels are the first group, the (m+1)th to the 2mth pixels are the second group, the (2m+1)th to the 3mth pixels are the third group, and so on, until the number of remaining pixels in the linear array is less than or equal to m, which is the last group, denoted as the nth group; S5: After the breakdown voltage is grouped, the breakdown voltage of each pixel is regulated by the independent upper electrode of each pixel. The control method in step S5 is as follows: 0V bias voltage is applied to the upper electrode of each pixel in the first group, 0.1V bias voltage is applied to the upper electrode of each pixel in the second group, 0.2V bias voltage is applied to the upper electrode of each pixel in the third group, and so on. In the last group, (n-1)×0.1V bias voltage is applied to the upper electrode of each pixel. S6: Select a voltage higher than the average voltage V B1 The voltage value is used as the working voltage of the SiC APD linear array. The working voltage is applied to the back electrode shared by the SiC APD linear array, enabling the SiC APD linear array to perform ultraviolet detection imaging.

2. The method for controlling the breakdown voltage of a SiC APD linear array according to claim 1, characterized in that, In step S1, the number of x pixels is 5 pixels.

3. The method for controlling the breakdown voltage of a SiC APD linear array according to claim 1, characterized in that, In step S1, the breakdown voltage is set by selecting the voltage value at which the current is 10nA as the breakdown voltage.

4. The method for controlling the breakdown voltage of a SiC APD linear array according to claim 1, characterized in that, The SiCAPD linear array is a 1×128 SiC APD linear array.

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