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

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

A retinal morphology photodetector for dynamic target detection

Technical field:

The design of the invention belongs to the field of photodetectors, specifically a retinal form photodetector capable of realizing dynamic target detection.

Background technique:

With the development of the Internet of Things, the detection and identification of moving objects is becoming more and more important. Traditional dynamic target detection systems are based on the traditional von Neumann architecture, that is, detection, storage and data processing are separated. This architecture makes a large number of useless signals transmitted from the detector side to the processor side through the data bus. The transmission process as well as the processing process will add a lot of useless energy consumption. In recent years, a new detector architecture has been developed - to complete the calculation operation inside the detector (integration of sensing and computing). At present, most of the work based on the integration of sensing and computing uses newly developed semiconductor materials such as two-dimensional materials or perovskite, which will inevitably face the problem of incompatibility with the current mature silicon technology. Therefore, it is very necessary to realize a dynamic target detector based on a sensor-computing integrated structure and compatible with silicon technology. The human visual system is an efficient dynamic target detection system, in which the Y-shaped ganglion cells on the retina only respond to changing light intensity signals, which greatly reduces the amount of information that is subsequently transmitted to the brain for data processing. And the response of the retina to the light intensity is in a logarithmic relationship with the light intensity, so that the degree of light intensity change can be directly obtained from the magnitude of the light response instead of the absolute value of the light intensity. Simulating the working form of the human visual system will help to achieve efficient dynamic target detection.

Capacitors can be used to block static signals and pass through changing signals. And the photosensitive chemical capacitance composed of metal/insulator/semiconductor can realize logarithmic response to light intensity. Therefore, the simulation of the light intensity response of the human visual system can be realized by using the metal/insulator/semiconductor structure.

Invention content:

Aiming at the problems existing in the current technology center, the purpose of the present invention is to realize a dynamic target detector compatible with silicon technology by simulating the light intensity response characteristics of the human visual system. Its remarkable advantage is that the detector will not output a signal for a constant light intensity signal, but when the light intensity changes, the detector will output a pulse electrical signal, and the pulse intensity is proportional to the ratio before and after the light intensity change.

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

The upper electrode (1) is composed of multiple independent closed-loop arrangements, and the number of closed loops corresponds to the number of pixels of the image sensor, and a larger number can achieve a clearer image detection result. And lead wires out on 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 closed-loop structure is preferably in the shape of a "mouth", with a side length of 500 μm and a line width of 10 μm.

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

The light absorbing layer (3) is intrinsic silicon with a thickness of 500 μm, a resistivity greater than 10 000 Ω·cm, and a size of 1 cm×1 cm.

The lower electrode (4) is made of copper, directly contacts with the light absorbing layer (3), and has a size of 2cm×5cm.

The preparation method of the novel photodetector is characterized in that the preparation method comprises the following steps:

a. The silicon dioxide on the surface of the intrinsic silicon is prepared by dry oxidation; one side of the intrinsic silicon is connected to the copper electrode;

b. Make the upper electrode

The upper surface of the device obtained in a uses the corresponding metal as the upper electrode by electron beam evaporation. The metal layer is uniform and the purity is greater than 99wt%.

The other side of the intrinsic silicon is connected to the prepared copper electrode.

The preparation of the upper electrode is to spin-coat photoresist on the obtained silicon/silicon dioxide substrate, obtain the reverse pattern of the corresponding electrode pattern through photolithography technology, and then remove the exposed photoresist with a developer, and then use Electron beam evaporation technology evenly evaporates titanium with a thickness of 10nm and gold with a thickness of 70nm on the photoresist, and then soaks in acetone solution to remove excess photoresist and excess metal to obtain electrodes with corresponding patterns.

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

The characteristic of the test process is the light source, which is incident from the closed loop of the upper electrode, such as the "mouth".

That is, the simulation of the light intensity response of the human visual system can be realized.

Description of drawings:

Figure 1 is a schematic diagram of the device structure

Figure 2 is the light intensity response diagram

Figure 3 is a schematic diagram of the test

Figure 4 is the sports car test

Detailed ways:

For the convenience of understanding, a specific case is introduced below in conjunction with the accompanying drawings: using this detector to detect the moving car.

(1) As shown in FIG. 1 , the upper electrode is fabricated on the intrinsic silicon by photolithography technology and electron beam evaporation technology. The specific method is to spin-coat photoresist (reverse glue) on the silicon wafer, expose it through the mask plate for 1.2s and pan-exposure for 22s, then develop, and then use the electron beam evaporation method to evaporate the gold electrode, and the evaporation rate is 2A/s , the current value is 12A, and finally the photoresist is washed off by the lift off process to form the top electrode on the substrate. The shape of the obtained top electrode is "口" shape, and a lead wire is drawn out on one side. The side length of the "口" shape is 500 μm, and the line width is 10 μm. The number of "口"-shaped electrodes corresponds to the number of pixels of the image sensor. The more the number, the clearer the image detection result can be achieved.

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

(3) Shine the moving image of the dynamic car on the detector, and test the current change on the detector.

Experimental data:

The light intensity irradiated on the detector will change due to the movement of the trolley. In this example, the front of the car will be dimmed and the back of the car will be variable. The corresponding pixels at the front end of the cart will generate a negative pulse signal, while at the rear end of the cart will generate a positive pulse signal. Combining all the pixels can get the outline of the car movement. For the static background, the detector does not respond, and the same information is unified. That is, the detection of moving targets is realized.

Claims (8)

1. A novel photodetector is characterized in that: the photodetector comprises an upper electrode (1), an insulating layer (2), a light absorbing layer (3), and a lower electrode (4) successively from top to bottom, wherein the upper electrode Titanium and gold, the insulating layer is silicon dioxide, the light absorbing layer is intrinsic silicon, and the bottom electrode is copper; The upper electrode (1) is composed of multiple independent closed-loop arrangements. The number of closed loops corresponds to the number of pixels of the image sensor. The larger the number, the clearer image detection results can be achieved; and lead wires are drawn from one side of each closed loop. 2. A novel photodetector according to claim 1, characterized in that: each closed-loop structure: the lower layer is 10nm thick titanium, and the upper layer is 70nm thick gold. 3. A novel photodetector according to claim 1, characterized in that the closed-loop structure is preferably in the shape of a "mouth", with a side length of 500 μm and a line width of 10 μm. 4. according to a kind of novel photodetector described in claim 1, it is characterized in that: insulating layer (2) is the silicon dioxide with 300nm thickness, is formed through dry oxygen oxidation process by light absorbing layer (3) surface. 5. A novel photodetector according to claim 1, characterized in that: the light absorbing layer (3) is intrinsic silicon with a thickness of 500 μm, a resistivity greater than 10 000 Ω·cm, and a size of 1 cm×1 cm. 6. A novel photodetector according to claim 1, characterized in that: the lower electrode (4) is copper, directly in contact with the light absorbing layer (3), and has a size of 2cm×5cm. 7. the preparation method of a kind of novel photodetector described in claim 1 is characterized in that, comprises the following steps: b. Make the upper electrode The upper surface of the device obtained in a uses the corresponding metal as the upper electrode by electron beam evaporation. The metal layer is uniform and the purity is greater than 99wt%. The other side of the intrinsic silicon is connected to the prepared copper electrode; The preparation of the upper electrode is to spin-coat photoresist on the obtained silicon/silicon dioxide substrate, obtain the reverse pattern of the corresponding electrode pattern through photolithography technology, and then remove the exposed photoresist with a developer, and then use Electron beam evaporation technology evenly evaporates titanium with a thickness of 10nm and gold with a thickness of 70nm on the photoresist, and then soaks in acetone solution to remove excess photoresist and excess metal to obtain electrodes with corresponding patterns. 8. the application of a kind of novel photodetector described in claim 1, upper electrode and lower electrode are connected with source meter respectively, source meter voltage is 0V, the variation of test current; The characteristic of the test process is the light source, which is incident from the closed loop of the upper electrode, such as the "mouth" shape; that is, the simulation of the light intensity response of the human visual system can be realized.

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