Quantum dot mid-infrared detector with ultrathin bi2se3 layer modified interface

Abstract

The application relates to the technical field of infrared detectors, in particular to a quantum dot mid-infrared detector with an interface modified by an ultrathin Bi2Se3 layer and a preparation method thereof. In the construction of an n-on-p structure mid-infrared HgTe colloidal quantum dot heterojunction device, an ultrathin Bi2Se3 layer with a layered structure and high electron mobility is introduced between HgTe CQDs and an n-type functional layer to form a non-epitaxial van der Waals contact-quantum dot stacking interface, so that the surface state of the HgTe colloidal quantum dots is modified, the transport characteristics of the carriers are improved, a built-in electric field is formed to promote the separation of the photo-generated carriers, and the mid-infrared detection response performance of the device is improved. The prepared quantum dot mid-infrared detector with a laminated structure and an interface modified by an ultrathin Bi2Se3 layer exhibits high working temperature characteristics that can work at a temperature higher than 77 K.

Description

Technical Field

[0001] This invention relates to the field of infrared detector technology, and in particular to a quantum dot mid-wave infrared detector with an ultrathin Bi2Se3 layer modified interface and its preparation method. Background Technology

[0002] Colloidal quantum dot infrared detectors are devices that use semiconductor nanocrystals (quantum dots) synthesized through solution methods as photosensitive materials. They are currently a research hotspot in the field of infrared technology, with core advantages including low cost, high operating temperature, tunable spectral range, and easy liquid-phase coupling with silicon-based integrated circuits. Based on the quantum confinement effect and solution-processable characteristics of colloidal quantum dot materials, the spectral detection wavelength range can be controlled by adjusting the type and size of the quantum dots. Furthermore, infrared detector fabrication processes do not require strict heteroepitaxial growth on lattice-matched substrates. Uniform quantum dot infrared optoelectronic thin films can be prepared using simple, rapid, and easily mass-producible techniques such as spin coating, blade coating, and spray coating. These films can then be used to construct simple and efficient photovoltaic infrared detectors through the stacked heterojunction quantum dot infrared detector.

[0003] As a zero-bandgap material, HgTe bulk colloidal quantum dots have a longer detection wavelength range, covering the mid-wave infrared and long-wave infrared bands. It is one of the main photosensitive materials for developing quantum dot mid-wave infrared detectors and has a relatively strong foundation in material synthesis, characterization and preparation research. However, in the development of mid-wave infrared detectors for application research, the device interface states are poor due to the influence of surface defect states of the material, resulting in low mid-wave infrared photoelectric detection performance. Summary of the Invention

[0004] The purpose of this invention is to address the problems caused by the increased size of mid-wave infrared HgTe colloidal quantum dots, which leads to an increase in nonpolar surfaces, resulting in more long-chain ligands coated on the surface, dangling bonds due to unsaturated coordination of Hg and Te atoms, and residual ligand impurities. These factors cause charge accumulation and deep-level traps at the semiconductor heterojunction interface, and the resulting interface defects significantly reduce the carrier mobility and lifetime of HgTe colloidal quantum dots, increase the trap-assisted tunneling current, and ultimately degrade device performance.

[0005] A quantum dot mid-wave infrared detector with an ultrathin Bi2Se3 layer modified interface, the detector consisting of, from bottom to top, a quartz substrate, an Au metal pixel electrode, an n-ZnO electron transport layer, an ultrathin Bi2Se3 interface modified layer, an HgTe CQDs photosensitive layer, a p-ZnTe hole transport layer, and an ITO transparent electrode layer.

[0006] The exciton absorption peak of the detector is 3.2 μm;

[0007] The thickness of the ultrathin Bi2Se3 interface modification layer is 6~10 nm.

[0008] A method for fabricating a quantum dot mid-wave infrared detector with an ultrathin Bi2Se3 layer modified interface includes the following steps:

[0009] S1, wet cleaning of quartz substrate;

[0010] S2 uses a mask to shield the quartz substrate and grows Au metal pixel electrodes by magnetron sputtering.

[0011] S3, n-ZnO electron transport layer is grown by magnetron sputtering on Au metal pixel electrode;

[0012] S4, an ultrathin Bi2Se3 interface modification layer is grown by magnetron sputtering on an n-ZnO electron transport layer;

[0013] S5, a mid-wave infrared HgTe CQDs solution with an exciton absorption peak of 3.2 μm was deposited on the Bi2Se3 interface modification layer using a ligand exchange film deposition process;

[0014] S6, p-ZnTe hole transport layer is grown on HgTe CQDs photosensitive layer by thermal evaporation;

[0015] S7, ITO transparent top electrode is grown by magnetron sputtering on HgTe CQDs photosensitive layer.

[0016] The thickness of the n-ZnO electron transport layer is 100-150 nm; the thickness of the HgTe CQDs photosensitive layer is 600-800 nm; the thickness of the ZnTe hole transport layer is 100-140 nm; and the thickness of the ITO transparent top electrode is 80-100 nm.

[0017] In step S7, after the mid-wave infrared transparent electrode layer is grown and the n-on-p structure device process is completed, a transparent top electrode is finally prepared under controlled conditions of low temperature and low energy damage using solution spin coating, physical vapor deposition, or dry transfer methods. Doped oxide transparent electrodes, silver nanowires, metal meshes, ultrathin metals, and carbon-based transparent conductive materials such as graphene and single-walled carbon nanotubes can be used to make it have high transmittance and conductivity in the mid-wave infrared band.

[0018] By introducing a layered ultrathin Bi₂Se₃ layer with high electron mobility between HgTe CQDs and an n-type functional layer, a non-epitaxy van der Waals contact-quantum dot stacking interface is formed. This modifies the surface state of the HgTe colloidal quantum dots, improves carrier transport properties, and simultaneously creates a built-in electric field to promote the separation of photogenerated carriers, thereby enhancing the mid-wave infrared detection response performance of the device. The mid-wave infrared quantum dot detector with the ultrathin Bi₂Se₃ layer-modified interface exhibits a high operating temperature characteristic, exceeding 77 K. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a quantum dot mid-infrared detector structure modified with ultrathin Bi2Se3.

[0020] Figure 2 The image shows the XRD characterization results of the ultrathin Bi2Se3 interface modified layer in Example 1.

[0021] Figure 3 The image shows the AFM characterization results of the ultrathin Bi2Se3 interface modification layer in Example 1.

[0022] Figure 4 The image shows the absorption spectrum of HgTe CQDs with an exciton absorption peak at 3.2 μm, as shown in Example 1.

[0023] Figure 5 The image shows a comparison of the physical samples before and after HgTe CQDs were deposited on the Bi2Se3 interface modification layer in Example 1.

[0024] Figure 6 This is the mid-infrared transmittance spectrum of the ITO transparent electrode in Example 1.

[0025] Figure 7 This is a comparison of the spectral response performance of the quantum dot mid-infrared detector with the ultrathin Bi2Se3 interface modified layer in Example 1 at different operating temperatures.

[0026] Figure 8 The results show the comparison of photoelectric response IV characteristic curves of quantum dot mid-infrared detectors with and without Bi2Se3 interface modification layers at an operating temperature of 120 K. Detailed Implementation

[0027] Example 1: A quantum dot mid-wave infrared detector with an interface modified by an ultrathin Bi2Se3 layer. The detector consists of, from bottom to top, a quartz substrate 1, an Au metal pixel electrode 2, an n-ZnO electron transport layer 3, an ultrathin Bi2Se3 interface modification layer 4, an HgTe CQDs photosensitive layer 5, a p-ZnTe hole transport layer 6, and an ITO transparent electrode layer 7.

[0028] A method for fabricating a quantum dot mid-wave infrared detector with an ultrathin Bi2Se3 layer modified interface includes the following steps:

[0029] S1, wet cleaning of a 2.5 cm × 2.5 cm quartz substrate was performed in a mixed solution of ammonia, hydrogen peroxide and deionized water.

[0030] S2 uses a mask to cover the quartz substrate and magnetron sputters Au metal pixel electrodes with a size of 3 mm × 3 mm under a 100 W DC power supply.

[0031] S3, an n-ZnO electron transport layer is grown by magnetron sputtering under a 100 W RF power supply, so that it covers the entire metal pixel area, and the thickness of the n-ZnO electron transport layer is 120 nm.

[0032] S4, the RF magnetron sputtering chamber is evacuated to below 8×10⁻⁶. -5 Below Pa, Ar2 was introduced as the sputtering gas, and an ultrathin Bi2Se3 interface modification layer was grown by magnetron sputtering at a power of 100 W. The thickness of the Bi2Se3 nanofilm was 9 nm.

[0033] S5, a mid-wave infrared HgTe CQDs solution with an exciton absorption peak of 3.2 μm was deposited on a Bi2Se3 interface modification layer, and a 750 nm photosensitive layer was finally obtained by ligand exchange film formation process.

[0034] S6 uses a low-energy-damage thermal evaporation method to deposit and grow a p-ZnTe hole transport layer with a thickness of 100 nm.

[0035] S7 is an ITO transparent top electrode with high transmittance in the mid-infrared region, grown by magnetron sputtering under low DC power, with a thickness of 80 nm.

[0036] By extending wires from the metal electrode and transparent electrode prepared by the above method, the spectral response performance of the quantum dot mid-wave infrared detector with the ultrathin Bi2Se3 layer modified interface prepared in Example 1 can be tested.

[0037] Figure 2 The XRD characterization results are of the ultrathin Bi2Se3 interface-modified layer grown by magnetron sputtering. It can be seen that the ultrathin Bi2Se3 layer has crystal diffraction peaks, indicating that it has crystallinity.

[0038] Figure 3 The AFM characterization results of the ultrathin Bi2Se3 interface-modified layer grown by magnetron sputtering show that it has low surface roughness.

[0039] Figure 4This is the mid-wave infrared absorption spectrum of HgTe CQDs with the exciton absorption peak located at 3.2 μm, which serves as the photosensitive layer material for this device.

[0040] from Figure 5 The image shows a Bi2Se3 interface modification layer grown on a transparent quartz substrate. It can be seen that the ultrathin Bi2Se3 layer has good light transmittance. After HgTe CQDs are coated, its light transmittance decreases. At the same time, HgTe CQDs can be uniformly attached and form a relatively dense photosensitive layer film.

[0041] Figure 6 It is a transparent ITO electrode in the mid-infrared band, which is grown by magnetron sputtering and has a transmittance of more than 70% in the 3~5 μm band.

[0042] Figure 7 This is a temperature-dependent spectral response diagram of a quantum dot mid-wave infrared detector with an ultrathin Bi2Se3 layer-modified interface. It can be seen that the device can operate over a wide temperature range and exhibits the strongest spectral response characteristics at an operating temperature of 120 K.

[0043] Comparative Example 1: Compared with the device prepared in Example 1, the only difference is that an ultrathin Bi2Se3 interface modification layer was not grown on n-ZnO, and all other layers are completely identical.

[0044] exist Figure 8 The image shows a comparison of the photoelectric response IV characteristic curves of quantum dot mid-infrared detectors with and without the Bi2Se3 interface modification layer at a working temperature of 120 K. Although the dark current density of quantum dot detectors with and without the Bi2Se3 interface modification layer is not significantly different in the dark state, the photocurrent density in the light state is quite different. At a bias voltage of -1 V, the photocurrent density of the device with the Bi2Se3 interface modification layer is 9 times that of the device without the Bi2Se3 interface modification layer, indicating that the Bi2Se3 interface modification layer can effectively improve the photoelectric response performance of this n-on-p structure device.

Claims

1. A quantum dot mid-wave infrared detector with an ultrathin Bi2Se3 layer modified interface, the detector consisting of, from bottom to top, a quartz substrate, an Au metal pixel electrode, an n-ZnO electron transport layer, an ultrathin Bi2Se3 interface modified layer, an HgTe CQDs photosensitive layer, a p-ZnTe hole transport layer, and an ITO transparent electrode layer; The exciton absorption peak of the detector is 3.2 μm; The thickness of the ultrathin Bi2Se3 interface modification layer is 6-10 nm.

2. The method for fabricating a quantum dot mid-wave infrared detector with an ultrathin Bi₂Se₃ layer modified interface as described in claim 1, characterized in that... Includes the following steps: S1, wet cleaning of quartz substrate; S2 uses a mask to shield the quartz substrate and grows Au metal pixel electrodes by magnetron sputtering. S3, n-ZnO electron transport layer is grown by magnetron sputtering on Au metal pixel electrode; S4, an ultrathin Bi2Se3 interface modification layer is grown by magnetron sputtering on an n-ZnO electron transport layer; S5, a mid-wave infrared HgTe CQDs solution with an exciton absorption peak of 3.2 μm was deposited on the Bi2Se3 interface modification layer using a ligand exchange film deposition process; S6, p-ZnTe hole transport layer is grown on HgTe CQDs photosensitive layer by thermal evaporation; S7, ITO transparent top electrode is grown by magnetron sputtering on HgTe CQDs photosensitive layer.

3. The quantum dot mid-wave infrared detector with an ultrathin Bi₂Se₃ layer modified interface as described in claim 1, characterized in that, The thickness of the n-ZnO electron transport layer is 100~150 nm; the thickness of the HgTe CQDs photosensitive layer is 600~800 nm; the thickness of the ZnTe hole transport layer is 100~140 nm; and the thickness of the ITO transparent top electrode is 80~100 nm.

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