Quantum dot semiconductor device for x-ray detection and method of making same

Abstract

The application discloses a kind of quantum dot semiconductor devices for X-ray detection and preparation method thereof.Mainly solve the existing X-ray detection device often needs complex data acquisition system and readout circuit, increase equipment cost and operation complexity, limit its application in portable imaging equipment, difficult to meet the technical problems of clinical real-time imaging needs.The device includes: semiconductor substrate layer, electron transport layer, quantum dot light-emitting layer, hole transport layer, light-emitting layer electrode, bottom electrode and electronic grade glass.The method uses semiconductor crystal material as substrate, combined with CdSe@CdS quantum dot light-emitting structure to construct heterojunction composite device.The application can realize direct imaging without complex system-level readout circuit, with the advantages of low dose, fast response, high sensitivity, suitable for medical X-ray imaging equipment.

Description

Technical Field

[0001] This invention relates to a quantum dot semiconductor device and its fabrication method, specifically to a quantum dot semiconductor device for X-ray detection and its fabrication method. Background Technology

[0002] X-ray imaging is widely used in medical imaging, industrial non-destructive testing, security inspection, and other fields. Traditional X-ray detectors mostly use silicon-based photodiodes, scintillators combined with photomultiplier tubes, which suffer from slow response speed, high noise, and difficulty in miniaturization. In recent years, with the development of quantum dot materials, quantum dot-based light-emitting devices have shown great potential in photoelectric conversion and detection due to their high quantum efficiency and tunable emission wavelength.

[0003] Semiconductor crystal materials are important X-ray detection media. For example, cadmium zinc telluride (CZT) crystals, with their high atomic number, high density, and excellent X-ray absorption capabilities, are often used in the manufacture of X-ray detectors. These types of semiconductor crystal materials can effectively reduce X-ray dose requirements while achieving fast response and high-sensitivity detection.

[0004] Existing X-ray detection devices often require complex data acquisition systems and readout circuits, which increases equipment costs and operational complexity, limiting their application in portable imaging devices and making it difficult to meet the needs of real-time clinical imaging.

[0005] Therefore, there is an urgent need to develop a novel semiconductor composite device based on a semiconductor crystal substrate combined with quantum dots. Summary of the Invention

[0006] The purpose of this invention is to address the technical problem that existing X-ray detection devices often require complex data acquisition systems and readout circuits, which increases equipment cost and operational complexity, limits their application in portable imaging devices, and makes it difficult to meet the needs of real-time clinical imaging. The invention provides a quantum dot semiconductor device for X-ray detection and its fabrication method.

[0007] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0008] A quantum dot semiconductor device for X-ray detection, characterized in that it includes:

[0009] A semiconductor substrate layer having opposing first and second surfaces;

[0010] An electron transport layer is formed on the first surface of the semiconductor substrate layer;

[0011] The quantum dot light-emitting layer is made of CdSe@CdS quantum dots; the quantum dot light-emitting layer is formed on the electron transport layer and is used to realize the direct conversion of X-rays to visible light;

[0012] A hole transport layer is formed on the quantum dot light-emitting layer;

[0013] The light-emitting electrode is formed on the hole transport layer;

[0014] The bottom electrode is formed on the second surface of the semiconductor substrate layer;

[0015] Electronic-grade glass is used to encapsulate a semiconductor substrate, electron transport layer, quantum dot light-emitting layer, hole transport layer, light-emitting layer electrode, and bottom electrode.

[0016] Furthermore, the hole transport layer includes:

[0017] The first hole transport layer is made of PVK and is formed on the quantum dot light-emitting layer.

[0018] The second hole transport layer is made of Poly-TPD and is formed on the first hole transport layer.

[0019] Furthermore, the semiconductor substrate layer is made of a semiconductor crystal with good X-ray absorption capability, so as to achieve low-dose, high-efficiency detection.

[0020] The electron transport layer is made of ZnMgO;

[0021] The light-emitting layer electrode is a composite metal electrode, which combines high optical transmittance and excellent conductivity.

[0022] Furthermore, the electronic-grade glass includes an ITO layer and a glass substrate arranged sequentially from the inside out.

[0023] Meanwhile, the present invention also provides a method for fabricating the aforementioned quantum dot semiconductor device for X-ray detection, characterized in that it includes the following steps:

[0024] Step 1: Semiconductor substrate preparation

[0025] A semiconductor substrate layer is formed by selecting a semiconductor crystal with a set resistivity and then cutting, grinding, polishing, and chemically etching it.

[0026] Step 2: Bottom Electrode Preparation

[0027] The bottom electrode is formed on the second surface of the semiconductor substrate by magnetron sputtering.

[0028] Step 3: Fabrication of the electron transport layer

[0029] An electron transport layer is formed on the first surface of the semiconductor substrate;

[0030] Step 4: Preparation of quantum dot light-emitting layer

[0031] A CdSe@CdS quantum dot solution was coated onto an electron transport layer using a spin-coating method to form a quantum dot luminescent layer.

[0032] Step 5: Preparation of the hole transport layer

[0033] A hole transport layer is formed on the quantum dot luminescent layer;

[0034] Step 6: Fabrication of the light-emitting layer electrode

[0035] Light-emitting electrode is formed on hole transport layer by vacuum thermal evaporation technology, and patterned using mask.

[0036] Step 7, Packaging

[0037] The semiconductor substrate, electron transport layer, quantum dot light-emitting layer, hole transport layer, light-emitting layer electrode, and bottom electrode are encapsulated using electronic-grade glass to complete the fabrication.

[0038] Furthermore, in step 1, the resistivity of the semiconductor crystal is higher than 10. 5 Ω•cm;

[0039] Step 2 specifically involves depositing an Au thin film as a bottom electrode on the second surface of the semiconductor substrate using a magnetron sputtering process.

[0040] Step 3 specifically involves: applying a ZnMgO precursor solution to the first surface of a semiconductor substrate using a spin coating method, followed by annealing to form an electron transport layer;

[0041] Step 5 specifically involves: using spin coating to sequentially coat PVK solution and Poly-TPD solution onto the quantum dot light-emitting layer, followed by annealing to form the first hole transport layer and the second hole transport layer;

[0042] Step 6 specifically involves depositing an Au layer on the hole transport layer using vacuum thermal evaporation technology, and then patterning it using a mask to form a light-emitting electrode.

[0043] Furthermore, in step 1, the semiconductor crystal is CZT, Si, or SiC.

[0044] Compared with the prior art, the present invention has the following beneficial technical effects:

[0045] 1. The quantum dot semiconductor device for X-ray detection of the present invention not only possesses excellent X-ray detection capabilities but also has a simple structure, is easy to integrate, and can directly realize the conversion of X-rays to visible light, making it particularly suitable for medical imaging systems and possessing broad application prospects. The device's low dose requirement, rapid response, and high sensitivity characteristics make it an ideal choice for next-generation medical X-ray imaging equipment.

[0046] 2. The quantum dot semiconductor device for X-ray detection of the present invention obtains the emission response curve and emission image of the device under different conditions by controlling the applied voltage and X-ray intensity, realizing direct imaging without complex system-level readout circuits, and is suitable for real-time diagnosis and rapid screening in medical imaging scenarios.

[0047] 3. The quantum dot semiconductor device for X-ray detection of the present invention exhibits a low dark current state when no X-rays are applied, while the photocurrent increases significantly under X-ray irradiation, with a difference of thousands of times, demonstrating excellent X-ray response performance and signal-to-noise ratio. This device has fast response characteristics, capable of completing X-ray signal conversion within milliseconds, while maintaining good performance under a 600V bias voltage, exhibiting good voltage withstand capability. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of an embodiment of a quantum dot semiconductor device for X-ray detection according to the present invention.

[0049] Figure 2 This is a schematic diagram showing the current-voltage response curves of a CZT-based quantum dot semiconductor device measured at different X-ray doses in an embodiment of the quantum dot semiconductor device for X-ray detection according to the present invention.

[0050] Figure 3 This is a schematic diagram of the quantum dot semiconductor device based on a CZT substrate acquiring light emission images at different voltages when X-rays with a current of 200 μA and a voltage of 50 kV are applied, according to an embodiment of the present invention. a represents 0 V, b represents 200 V, and c represents 600 V.

[0051] The annotations in the attached figures are explained as follows:

[0052] 1-Semiconductor substrate, 2-Electron transport layer, 3-Quantum dot light-emitting layer, 4-Hole transport layer, 41-First hole transport layer, 42-Second hole transport layer; 5-Light-emitting layer electrode, 6-Bottom electrode, 7-ITO layer, 8-Glass substrate. Detailed Implementation

[0053] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] like Figure 1 As shown, this embodiment provides a quantum dot semiconductor device for X-ray detection, which mainly includes a semiconductor substrate layer 1, an electron transport layer 2, a hole transport layer 4, a light-emitting layer electrode 5, and a bottom electrode 6.

[0055] The semiconductor substrate 1 is made of semiconductor crystal material, which utilizes its excellent X-ray absorption capability to achieve low-dose, high-efficiency detection. Furthermore, a first surface and a second surface are disposed opposite to each other on the semiconductor substrate 1.

[0056] The electron transport layer 2 is disposed on the first surface of the semiconductor substrate layer 1 and is made of ZnMgO. Its main function is to effectively collect and transport electron carriers.

[0057] The quantum dot light-emitting layer 3 is disposed on the electron transport layer 2. The material is CdSe@CdS quantum dots, which can emit red light, thereby realizing the conversion of X-rays to visible light.

[0058] The hole transport layer 4 includes a first hole transport layer 41 and a second hole transport layer 42. The first hole transport layer 41 is made of PVK and is disposed on the quantum dot light-emitting layer 3. The second hole transport layer 42 is made of Poly-TPD and is disposed on the first hole transport layer 41. By combining the hole transport layer 4 structures, hole transport efficiency can be optimized.

[0059] The light-emitting layer electrode 5 is disposed on the second hole transport layer 42. It is a thin-layer composite metal electrode prepared by magnetron sputtering and has high optical transmittance and excellent conductivity.

[0060] The bottom electrode 6 is disposed on the second surface of the semiconductor substrate layer 1. Electronic-grade glass is encapsulated over the semiconductor substrate layer 1, electron transport layer 2, quantum dot light-emitting layer 3, hole transport layer 4, light-emitting layer electrode 5, and bottom electrode 6. Specifically, the electronic-grade glass employs a double-layer structure with an ITO layer 7 and a glass substrate 8 disposed sequentially from the inside out, thereby preventing interference from the external environment.

[0061] The aforementioned device is fabricated using the following steps:

[0062] Step 1: Select a material with a resistivity higher than 10. 5 Using a CZT single crystal with an Ω•cm content as a substrate, a wafer with a smooth and flat surface is obtained after cutting, grinding, polishing and chemical etching.

[0063] Step 2, Preparation of bottom electrode 6: An Au thin film is deposited on the back side of the CZT substrate as a cathode by magnetron sputtering.

[0064] Step 3, Preparation of electron transport layer 2: The ZnMgO precursor solution was coated onto the cathode by spin coating and then annealed to form electron transport layer 2.

[0065] Step 4: Preparation of quantum dot luminescent layer 3: CdSe@CdS red quantum dot solution is coated onto electron transport layer 2 using spin coating to form the luminescent layer;

[0066] Step 5, Preparation of hole transport layer 4: PVK solution and Poly-TPD solution are coated onto the light-emitting layer by spin coating and annealed at room temperature to form hole transport layer 4;

[0067] Step 6: Fabrication of the light-emitting layer electrode 5: An Au layer is deposited on the hole injection layer using vacuum thermal evaporation technology, and patterned using a mask to form the light-emitting layer electrode 5;

[0068] Step 7: Packaging: Finally, the device is packaged using electronic-grade glass.

[0069] The fabricated device underwent several performance tests, the specific tests are as follows:

[0070] See Figure 2 X-ray response testing: The current-voltage response curves of the device were measured under different X-ray doses. The results showed that the photocurrent continuously increased with increasing bias voltage. At a bias voltage of 200V, the dark current of the device was less than 100 nA without X-rays, while the photocurrent reached over 100,000 nA after applying X-rays (current 200 μA, voltage 50 kV), demonstrating excellent X-ray response performance.

[0071] See Figure 3 Withstand voltage test: The test was conducted under X-rays with a current of 200μA and a voltage of 50 kV, increasing the voltage from 0V to 600V (i.e., from 0V to 600V). Figure 3 (a to c) The device can emit light stably at voltages up to 600V without any breakdown.

[0072] Luminous uniformity test: Images of the device's luminous emission were captured using a CMOS camera. After image processing and analysis, the luminous area of ​​the device was found to be concentrated in the center, indicating good luminous uniformity, which meets the requirements of practical applications.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A quantum dot semiconductor device for X-ray detection, characterized in that, include: A semiconductor substrate layer (1) has a first surface and a second surface opposite to each other; An electron transport layer (2) is formed on the first surface of the semiconductor substrate layer (1); The quantum dot light-emitting layer (3) is made of CdSe@CdS quantum dots; the quantum dot light-emitting layer (3) is formed on the electron transport layer (2) and is used to realize the direct conversion of X-rays to visible light; Hole transport layer (4) is formed on the quantum dot light-emitting layer (3); The light-emitting electrode (5) is formed on the hole transport layer (4); The bottom electrode (6) is formed on the second surface of the semiconductor substrate layer (1); Electronic-grade glass is used to encapsulate a semiconductor substrate (1), an electron transport layer (2), a quantum dot light-emitting layer (3), a hole transport layer (4), a light-emitting layer electrode (5), and a bottom electrode (6).

2. The quantum dot semiconductor device for X-ray detection according to claim 1, characterized in that, The hole transport layer (4) includes: The first hole transport layer (41) is made of PVK and is formed on the quantum dot light-emitting layer (3). The second hole transport layer (42) is made of Poly-TPD and is formed on the first hole transport layer (41).

3. The quantum dot semiconductor device for X-ray detection according to claim 1 or 2, characterized in that: The semiconductor substrate layer (1) is made of semiconductor crystal; The electron transport layer (2) is made of ZnMgO; The light-emitting layer electrode (5) is a composite metal electrode.

4. The quantum dot semiconductor device for X-ray detection according to claim 3, characterized in that: The electronic-grade glass includes an ITO layer (7) and a glass substrate (8) arranged sequentially from the inside to the outside.

5. A method for fabricating a quantum dot semiconductor device for X-ray detection as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1, Semiconductor substrate layer (1) preparation A semiconductor substrate layer is formed by cutting, grinding, polishing and chemical etching a semiconductor crystal with a set resistivity (1); Step 2, Preparation of bottom electrode (6) A bottom electrode (6) is formed on the second surface of the semiconductor substrate (1) by magnetron sputtering. Step 3, Preparation of electron transport layer (2) An electron transport layer (2) is formed on the first surface of the semiconductor substrate (1); Step 4: Preparation of quantum dot light-emitting layer (3) A CdSe@CdS quantum dot solution was coated onto the electron transport layer (2) using spin coating to form a quantum dot luminescent layer (3); Step 5, Hole transport layer (4) preparation A hole transport layer (4) is formed on the quantum dot light-emitting layer (3); Step 6: Preparation of the light-emitting layer electrode (5) The light-emitting electrode (5) is formed on the hole transport layer (4) by vacuum thermal evaporation technology and patterned using a mask. Step 7, Packaging The semiconductor substrate (1), electron transport layer (2), quantum dot light-emitting layer (3), hole transport layer (4), light-emitting layer electrode (5) and bottom electrode (6) are encapsulated using electronic-grade glass to complete the fabrication.

6. The method for fabricating a quantum dot semiconductor device for X-ray detection according to claim 5, characterized in that: In step 1, the resistivity of the semiconductor crystal is higher than 10. 5 Ω•cm; Step 2 specifically involves depositing an Au thin film as a bottom electrode (6) on the second surface of the semiconductor substrate layer (1) using a magnetron sputtering process; Step 3 specifically involves: applying a ZnMgO precursor solution to the first surface of the semiconductor substrate (1) using a spin coating method, and then forming an electron transport layer (2) after annealing. Step 5 specifically involves: using spin coating to sequentially coat PVK solution and Poly-TPD solution onto the quantum dot light-emitting layer (3), and then annealing to form the first hole transport layer (41) and the second hole transport layer (42); Step 6 specifically involves depositing an Au layer on the hole transport layer (4) using vacuum thermal evaporation technology, and then patterning it using a mask to form a light-emitting electrode (5).

7. The method for fabricating a quantum dot semiconductor device for X-ray detection according to claim 6, characterized in that: In step 1, the semiconductor crystal is CZT, Si, or SiC.

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