CN115692539A

CN115692539A - Retina form photoelectric detector capable of realizing dynamic target detection

Info

Publication number: CN115692539A
Application number: CN202211394928.3A
Authority: CN
Inventors: 张永哲; 武一; 陈小青; 邓文杰
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2022-11-08
Filing date: 2022-11-08
Publication date: 2023-02-03

Abstract

A retina form photoelectric detector capable of realizing dynamic target detection belongs to the field of photoelectric detectors. The photoelectric detector sequentially comprises an upper electrode (1), an insulating layer (2), a light absorption layer (3) and a lower electrode (4) from top to bottom, wherein the upper electrode is made of titanium and gold, the insulating layer is made of silicon dioxide, the light absorption layer is made of intrinsic silicon, and the lower electrode is made of copper. The upper electrode (1) is formed by arranging a plurality of independent closed loops, the number of the closed loops corresponds to the number of pixels of the image sensor, and more closed loops can realize clearer image detection results. And leads are led out from one side of each closed loop. Each closed-loop structure: the lower layer is 10nm thick titanium and the upper layer is 70nm thick gold. The detector does not output signals for the unchanged light intensity signals, when the light intensity changes, the detector outputs a pulse electric signal, and the ratio of the pulse intensity to the light intensity before and after the change is in a direct proportion relation.

Description

Retina form photoelectric detector capable of realizing dynamic target detection

The technical field is as follows:

the invention belongs to the field of photoelectric detectors, and particularly relates to a retina form photoelectric detector capable of realizing dynamic target detection.

Background art:

with the development of the internet of things, the detection and identification of moving objects become more and more important. Traditional dynamic object detection systems are based on the traditional von neumann architecture, i.e. the detection, storage and data processing are separate. This architecture allows a large number of unwanted signals to be transmitted from the detector side to the processor side via the data bus. Both the transport and the treatment process add significant and useless energy consumption. In recent years, a new detector architecture has been developed, in which the calculation operation (sensory integration) is performed inside the detector. Current work on computational integration mostly utilizes newly developed semiconductor materials such as two-dimensional materials or perovskites, which necessarily suffer from incompatibility with the current mature silicon process. It is therefore necessary to realize a dynamic target detector based on a perceptually integrated structure and compatible with silicon processes. The human visual system is an efficient dynamic target detection system, wherein the Y-shaped ganglion cells on the retina only respond to the changed light intensity signals, and the information quantity subsequently transmitted to the brain for data processing is greatly reduced. And the response of the retina to light intensity is logarithmic with respect to light intensity, so that the degree of light intensity change can be directly derived from the magnitude of the light response rather than the absolute value of the light intensity. Simulating the working form of the human visual system will help to achieve efficient dynamic target detection.

The blocking of static signals and the passing of varying signals can be achieved by means of capacitors. And a logarithmic response to light intensity can be achieved using a photosensitive chemical capacitor of metal/insulator/semiconductor composition. Therefore, simulation of the light intensity response of the human visual system can be realized by using the metal/insulator/semiconductor structure.

The invention content is as follows:

aiming at the problems existing in the prior art center, the invention aims to realize a dynamic target detector compatible with a silicon process by simulating the light intensity response characteristic of a human visual system. The detector has the obvious advantages that the detector can not output signals for the unchanged light intensity signals, when the light intensity changes, the detector can output a pulse electric signal, and the ratio of the pulse intensity to the light intensity before and after the change is in a direct proportion relation.

A novel photoelectric detector is characterized in that: the photoelectric detector sequentially comprises an upper electrode (1), an insulating layer (2), a light absorption layer (3) and a lower electrode (4) from top to bottom, wherein the upper electrode is made of titanium and gold, the insulating layer is made of silicon dioxide, the light absorption layer is made of intrinsic silicon, and the lower electrode is made of copper.

The upper electrode (1) is formed by arranging a plurality of independent closed loops, the number of the closed loops corresponds to the number of pixels of the image sensor, and more closed loops can realize clearer image detection results. And leads are led out from one side of each closed loop. Each closed-loop structure: the lower layer was 10nm thick titanium and the upper layer was 70nm thick gold.

The closed loop structure is preferably in a shape of a Chinese character 'kou', the side length is 500 mu m, and the line width is 10 mu m.

The insulating layer (2) is made of silicon dioxide with a thickness of 300nm and is formed on the surface of the light absorption layer (3) by a dry oxygen oxidation method.

The light absorbing layer (3) is made of intrinsic silicon 500 μm thick, has a resistivity of more than 10 000. Omega. Cm, and has a size of 1cm × 1cm.

The lower electrode (4) is copper and is in direct contact with the light absorption layer (3) and has a size of 2cm × 5cm.

The preparation method of the novel photoelectric detector is characterized by comprising the following steps:

a. preparing silicon dioxide on the surface of the intrinsic silicon upper surface by dry oxidation; one side of the intrinsic silicon is connected with the copper electrode;

b. making the top electrode

Using the metal corresponding to the electron beam evaporation on the upper surface of the device obtained in the step a as an upper electrode, wherein the metal layer is uniform, the purity of the metal layer is more than 99wt%, the closed loop shape of the upper electrode is preferably in a shape of a Chinese character 'kou', and a lead is led out to be connected with an external test circuit;

the other side of the intrinsic silicon is connected with a prepared copper electrode.

The preparation of the upper electrode is specifically that photoresist is coated on the obtained silicon/silicon dioxide substrate in a spinning mode, an inverse pattern corresponding to an electrode pattern is obtained through a photoetching technology, then the exposed photoresist is removed through developing solution, titanium with the thickness of 10nm and gold with the thickness of 70nm are evenly evaporated on the photoresist through an electron beam evaporation technology, and then redundant photoresist and redundant metal are removed through soaking in acetone solution, so that the electrode with the corresponding pattern is obtained.

The upper electrode and the lower electrode are respectively connected with a source meter, the voltage of the source meter is 0V, and the change of the current is tested.

The test procedure is characterized by a light source, which is incident from the closed loop of the upper electrode, such as a square.

I.e. a simulation of the light intensity response of the human visual system can be achieved.

Description of the drawings:

FIG. 1 is a schematic diagram of a device structure

FIG. 2 is a light intensity response diagram

FIG. 3 is a schematic diagram of the test

FIG. 4 is a moving cart test

The specific implementation mode is as follows:

for ease of understanding, a specific case is described below in conjunction with the appended drawings: the detector is used for realizing the detection of the moving trolley.

(1) As shown in fig. 1, an upper electrode is fabricated on intrinsic silicon using photolithography and electron beam evaporation. The specific method comprises the steps of spin-coating photoresist (reverse photoresist) on a silicon wafer, carrying out ultraviolet exposure for 1.2s for 22s through a mask plate, then developing, then evaporating a gold electrode by using an electron beam evaporation method, wherein the evaporation rate is 2A/s, the current value is 12A, and finally washing off the photoresist through a lift off process to form a top electrode on a substrate. The obtained top electrode is in a shape of a Chinese character 'kou', and a lead is led out from one side of the top electrode. The side length of the square shape of the Chinese character kou is 500 mu m, the line width is 10 mu m, the number of the square electrodes corresponds to the number of pixels of the image sensor, and the clearer image detection result can be realized when the number of the square electrodes is larger.

(2) The sample is placed on a copper plate of a photoelectric test platform, the upper electrode and the copper plate are respectively connected with a semiconductor analyzer, and the change of current along with time is tested.

(3) And (4) irradiating the moving image of the dynamic trolley on the detector, and testing the current change on the detector.

Experimental data:

the movement of the trolley causes the intensity of light impinging on the detector to vary. In this example, the front of the cart would be darkened and the cart rear would be variable. The corresponding pixels at the front of the cart will generate a negative pulse signal and the corresponding pixels at the rear of the cart will generate a positive pulse signal. The outline of the trolley movement can be obtained by integrating all the pixels. The detector does not respond to the static background, and the information is unified into the same information. Namely, the detection of the moving object is realized.

Claims

1. A novel photodetector, characterized by: the photoelectric detector sequentially comprises an upper electrode (1), an insulating layer (2), a light absorption layer (3) and a lower electrode (4) from top to bottom, wherein the upper electrode is made of titanium and gold, the insulating layer is made of silicon dioxide, the light absorption layer is made of intrinsic silicon, and the lower electrode is made of copper;

the upper electrode (1) is formed by arranging a plurality of independent closed loops, the number of the closed loops corresponds to the number of pixels of the image sensor, and the more the number is, the clearer image detection result can be realized; and leads are led out at one side of each closed loop.

2. A novel photodetector according to claim 1, characterized in that: each closed-loop structure: the lower layer was 10nm thick titanium and the upper layer was 70nm thick gold.

3. A novel photodetector according to claim 1, characterized in that: the closed loop structure is preferably in a shape of a Chinese character 'kou', the side length is 500 mu m, and the line width is 10 mu m.

4. A novel photodetector according to claim 1, characterized in that: the insulating layer (2) is made of silicon dioxide with a thickness of 300nm and is formed on the surface of the light absorbing layer (3) by a dry oxygen oxidation method.

5. A novel photodetector according to claim 1, characterized in that: the light absorbing layer (3) is made of intrinsic silicon 500 μm thick, has a resistivity of more than 10 000. Omega. Cm, and has a size of 1cm × 1cm.

6. A novel photodetector according to claim 1, characterized in that: the lower electrode (4) is made of copper, is directly contacted with the light absorption layer (3), and has the size of 2cm multiplied by 5cm.

7. The method of claim 1, further comprising the steps of:

b. making the top electrode

the other side of the intrinsic silicon is connected with a prepared copper electrode;

the preparation of the upper electrode is specifically that photoresist is coated on the obtained silicon/silicon dioxide substrate in a spinning mode, an inverse pattern corresponding to an electrode pattern is obtained through a photoetching technology, then exposed photoresist is removed through developing solution, titanium with the thickness of 10nm and gold with the thickness of 70nm are evenly evaporated on the photoresist through an electron beam evaporation technology, and then redundant photoresist and redundant metal are removed through soaking in acetone solution, and the electrode with the corresponding pattern is obtained.

8. The application of the novel photoelectric detector as claimed in claim 1, wherein the upper electrode and the lower electrode are respectively connected with a source meter, the voltage of the source meter is 0V, and the change of the current is tested;

the characteristic in the test process is that the light source is incident from the closed loop of the upper electrode like a square; i.e. a simulation of the light intensity response of the human visual system can be achieved.