A method for reducing the linear correlation coefficient of the spectral response of a detector

Abstract

The application discloses a kind of regulation and control methods for reducing the linear correlation coefficient of detector spectral response.Solve the problem that the response signal of different wavelength channels of detector is difficult to distinguish in narrowband and spectral detection.Different wavelength incident light is incident from the left electrode of the spectral detector, and different wavelength light is absorbed by a specific area of the multilayer energy band gap semiconductor absorption layer.The electron affinity of the semiconductor absorption layer is regulated to make the spatial charge density distribution of the detector different and the electric field strength change, thereby causing the collection of photo-generated carriers generated by incident light to be different, and finally the spectral response characteristics of the detector under different bias voltages can be regulated.The correlation coefficient of the spectral response curve is reduced from 0.99 to 0.56.The application provides an effective detection signal guarantee for subsequent spectral information reconstruction.

Description

Technical Field

[0001] This invention belongs to the field of spectral detection technology, specifically relating to a method for adjusting the linear correlation coefficient of the spectral response of a detector. Background Technology

[0002] The photoelectric effect in semiconductors converts the energy of incident light into an electrical signal, and outputs the detection signal through a readout circuit. This is a common method for photoelectric detection. Generally, when the photon energy of the incident light is greater than the band gap of the semiconductor, the incident photon energy is absorbed by the semiconductor material, and some valence band electrons transition to the conduction band, forming photogenerated electron / hole pairs. If there is an appropriate bias electric field in the detector, the photogenerated electron / hole pairs will separate under the influence of the bias electric field, and form a detection current through drift and diffusion. Therefore, when designing broadband photodetectors, the main focus is on selecting a suitable band gap for the active material to improve the internal quantum efficiency of photoelectric conversion. Simultaneously, by designing pn junctions or pin junctions, the external quantum efficiency of photoelectric detection can be improved, and dark current and noise can be reduced.

[0003] Besides broadband detection, narrowband and spectral detection also have numerous applications. To improve detector integration, recent research has reported on narrowband and spectral detection schemes that do not employ filters or dispersive optical elements. Some research teams have proposed increasing defect density in certain regions through defect design, thereby suppressing short-wavelength photon-generated response signals by increasing carrier recombination, thus achieving narrowband detection performance. Other literature reports the use of combinations of semiconductor materials with different bandgap and carrier recombination manipulation to reconstruct incident spectral information using a series of uncorrelated broadband detection responses, obtaining multispectral or hyperspectral detection without dispersive optical elements. Although these studies demonstrate that controlling photogenerated carrier recombination can influence the detector's spectral response characteristics to some extent, the obtained detector spectral response characteristics still exhibit high linear correlation, making it difficult to obtain accurate reconstructed spectra through wavelength division multiplexing, resulting in poor spectral resolution.

[0004] Therefore, there is an urgent need for a new technical solution to address this problem. Summary of the Invention

[0005] Technical Problem: The purpose of this invention is to address the shortcomings of existing technologies by providing a method for reducing the linear correlation coefficient of the detector's spectral response. This method can achieve spectral responses with low linear correlation under different bias voltages, thereby improving the accuracy of wavelength division multiplexing (WDM) algorithms in reconstructing spectral information and simultaneously achieving high spectral and spatial resolution.

[0006] Technical solution: This invention provides a method for reducing the linear correlation coefficient of the detector's spectral response. This method designs the electron affinity potential of different semiconductor layers of the detector and uses photogenerated carrier recombination to modulate the detection signal of different wavelength channels, ultimately making the detector's spectral response characteristics exhibit large nonlinearity under different bias voltages.

[0007] The present invention discloses a method for reducing the linear correlation coefficient of the detector's spectral response. Different wavelengths of incident light are incident from the left electrode of the spectral detector. The light of different wavelengths is absorbed by specific regions of a multilayer energy bandgap semiconductor absorption layer. By controlling the electron affinity of the semiconductor absorption layer, the space charge density distribution and electric field intensity of the detector are made different, thereby causing differences in the collection of photogenerated carriers generated by the incident light. Ultimately, the spectral response characteristics of the detector can be controlled under different bias voltages.

[0008] The detector has the following structure from left to right: left electrode, heavily doped p+ layer, p-type layer, first intrinsic layer, second intrinsic layer, n-type layer, heavily doped n+ layer, and right electrode; the band gap of the above semiconductor layers varies from large to small, i.e., Eg1≥Eg2≥Eg3≥Eg4.

[0009] The heavily doped p+ and heavily doped n+ layers, with a thickness of less than 0.3 μm, enable the detector to make ohmic contact with the left electrode at the incident end and the right electrode at the exit end.

[0010] The semiconductor absorber layer includes a p-type layer, a first intrinsic layer, a second intrinsic layer, and an n-type layer. Its electron affinity can be controlled by selecting semiconductor materials with different electron affinity, ion doping the semiconductor material, or defect design of the semiconductor material.

[0011] The semiconductor absorption layer is a bulk material with high light absorption rate covering the ultraviolet-near infrared range.

[0012] The bulk materials with high light absorption rates include silicon, perovskite, quantum dots, and combinations thereof.

[0013] The semiconductor absorber layer is prepared by solution epitaxy, spin coating, and spray coating.

[0014] The left and right electrodes are metal electrodes or conductive oxide electrodes.

[0015] Beneficial effects: The advantages of this invention are as follows

[0016] 1. This invention, through semiconductor layer structure design, can control the recombination rate of photogenerated carriers by regulating the electron affinity potential of the semiconductor layer, and ultimately change the spectral response curve of the detector, thus exploring a new technical path for wavelength division multiplexing reconstructed spectral detection.

[0017] 2. The detectable spectral range and spectral response characteristics are adjustable, the method is simple, and it has application flexibility.

[0018] 3. This invention achieves integrated filtering and detection in a single device structure, enabling direct color recognition without the need for spectroscopic optical components. Attached Figure Description

[0019] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein:

[0020] Figure 1 This is the device structure of the detector described in this invention. It includes a left electrode 1, a heavily doped p+ layer 2, a p-type layer 3, a first intrinsic layer 4, a second intrinsic layer 5, an n-type layer 6, a heavily doped n+ layer 7, and a right electrode 8.

[0021] Figure 2 The photogenerated carrier generation rate of the four-layer heterojunction described in this invention;

[0022] Figure 3 The spectral response characteristic curve obtained from simulation in Embodiment 1 of the present invention;

[0023] Figure 4 The spectral response characteristic curve obtained from simulation in Embodiment 2 of the present invention;

[0024] Figure 5 The spectral response characteristic curve obtained from simulation in Example 3 of this invention;

[0025] Figure 6 The spectral response characteristic curve obtained from simulation in Example 4 of this invention;

[0026] Figure 7 The image shows the spectral response curve obtained from the simulation of Comparative Example 1 of this invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be fully described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0028] The present invention provides a method for reducing the linear correlation coefficient of the detector's spectral response. Different wavelengths of incident light are incident from the left electrode of the spectral detector. The light of different wavelengths is absorbed by specific regions of the multilayer energy bandgap semiconductor absorption layer. By controlling the electron affinity of the semiconductor absorption layer, the space charge density distribution and electric field intensity of the detector are made different, which leads to differences in the collection of photogenerated carriers generated by the incident light. Ultimately, the spectral response characteristics of the detector can be controlled under different bias voltages.

[0029] The method for reducing the linear correlation coefficient of the detector spectral response described in this invention is as follows:

[0030] Figure 1 This is the device structure of the detector described in this invention. It includes a left electrode 1, a heavily doped p+ layer 2, a p-type layer 3, a first intrinsic layer 4, a second intrinsic layer 5, an n-type layer 6, a heavily doped n+ layer 7, and a right electrode 8. When incident light shines on the detector from left to right, the incident photons are first absorbed by the semiconductor material through the photoelectric effect, generating photogenerated carriers. For example... Figure 2 As shown, short-wavelength incident light has a relatively strong penetration depth, and photogenerated carriers are mainly generated in the second, third, and fourth semiconductor layers. With increasing incident light wavelength, the wide-bandgap semiconductor becomes almost transparent to the incident light, while long-wavelength incident light is mainly absorbed by the third and fourth semiconductor layers. The drift and recombination of photogenerated carriers in a photodetector are determined by the detector's band structure and electric field distribution. By modulating the electron affinity of the semiconductor layers, differences in the space charge density distribution and electric field intensity are created, leading to differences in the collection of photogenerated carriers generated by the incident light. Ultimately, this allows for the tuning of the detector's spectral response characteristics under different bias voltages.

[0031] The energy band gaps of the four semiconductor absorption layers selected in this embodiment of the invention are 3.09 eV, 2.51 eV, 1.94 eV, and 1.36 eV, respectively. The doping concentrations of the p-type and n-type layers are 10. 15 / cm 3 Additionally, p + and n + Layer doping concentration is 10 18 / cm 3 .

[0032] Example 1

[0033] Incident light containing different wavelength components enters from the left electrode 1 at the left end of the detector. At the left end of the four semiconductor absorption layers is a p-type layer 3 with a band gap of Eg1; behind the p-type layer are two intrinsic layers, namely the first intrinsic layer 4 and the second intrinsic layer 5, with energy band gaps of Eg2 and Eg3, respectively; behind the intrinsic layers is an n-type layer 6 with an energy band gap of Eg4.

[0034] The band gap of the aforementioned semiconductor absorption layer varies from large to small, i.e., Eg1≥Eg2≥Eg3≥Eg4. To ensure ohmic contact between the detector and the incident and emitted electrodes, very thin heavily doped p+ and n+ layers are respectively formed at both ends of the p-type and n-type layers. The thickness of each semiconductor absorption layer is 10 μm, and the thickness of the heavily doped layer is 0.1 μm.

[0035] The electron affinities of each semiconductor layer are 3.26 eV, 3.54 eV, 3.83 eV, and 4.07 eV, respectively. The incident light wavelength range is 400 nm to 900 nm.

[0036] The spectral response characteristic curve obtained from the detector simulation in Example 1 is as follows: Figure 3 As shown, the linear correlation is high under different bias voltages, and the correlation coefficient of the spectral response curve of the detector is 0.86.

[0037] Example 2

[0038] Incident light containing different wavelength components enters from the left electrode 1 at the left end of the detector. At the left end of the four semiconductor absorption layers is a p-type layer 3 with a band gap of Eg1; behind the p-type layer are two intrinsic layers, namely the first intrinsic layer 4 and the second intrinsic layer 5, with energy band gaps of Eg2 and Eg3, respectively; behind the intrinsic layers is an n-type layer 6 with an energy band gap of Eg4.

[0039] The band gap of the aforementioned semiconductor layers decreases gradually from large to small, i.e., Eg1≥Eg2≥Eg3≥Eg4. To ensure ohmic contact between the detector and the incident and emitted electrodes, very thin, heavily doped p+ and n+ layers are respectively placed at both ends of the p-type and n-type layers. Each semiconductor layer is 10 μm thick, and the heavily doped layer is 0.2 μm thick.

[0040] The electron affinities of each semiconductor layer are 3.21 eV, 3.49 eV, 3.78 eV, and 4.07 eV, respectively. The incident light wavelength range is 400 nm to 900 nm.

[0041] The spectral response curve obtained from the detector simulation in Example 2 is as follows: Figure 4 As shown, compared to the detector in Example 1, the linear correlation decreases under different bias voltages, and the correlation coefficient of the spectral response curve of this detector is 0.79.

[0042] Example 3

[0043] Incident light containing different wavelength components enters from the left electrode 1 at the left end of the detector. At the left end of the four semiconductor absorption layers is a p-type layer 3 with a band gap of Eg1; behind the p-type layer are two intrinsic layers, namely the first intrinsic layer 4 and the second intrinsic layer 5, with energy band gaps of Eg2 and Eg3, respectively; behind the intrinsic layers is an n-type layer 6 with an energy band gap of Eg4.

[0044] The band gap of the aforementioned semiconductor layers varies from large to small, i.e., Eg1≥Eg2≥Eg3≥Eg4. To ensure ohmic contact between the detector and the incident and emitted electrodes, very thin heavily doped p+ and n+ layers are respectively placed at both ends of the p-type and n-type layers. Each semiconductor layer is 10 μm thick, and the heavily doped layer is 0.3 μm thick.

[0045] The electron affinities of each semiconductor layer are 3.16 eV, 3.44 eV, 3.73 eV, and 4.07 eV, respectively. The incident light wavelength range is 400 nm to 900 nm.

[0046] The spectral response characteristic curve obtained from the detector simulation in Example 3 is as follows: Figure 5 As shown, compared to the detector in Example 2, the linear correlation of the spectral response under different bias voltages is further reduced, and the correlation coefficient of the spectral response curve of this detector is 0.65.

[0047] Example 4

[0048] Incident light containing different wavelength components enters from the left electrode 1 at the left end of the detector. At the left end of the four semiconductor absorption layers is a p-type layer 3 with a band gap of Eg1; behind the p-type layer are two intrinsic layers, namely the first intrinsic layer 4 and the second intrinsic layer 5, with energy band gaps of Eg2 and Eg3, respectively; behind the intrinsic layers is an n-type layer 6 with an energy band gap of Eg4.

[0049] The band gap of the aforementioned semiconductor layers varies from large to small, i.e., Eg1≥Eg2≥Eg3≥Eg4. To ensure ohmic contact between the detector and the incident and emitted electrodes, very thin, heavily doped p+ and n+ layers are respectively placed at both ends of the p-type and n-type layers. Each semiconductor layer is 10 μm thick, and the heavily doped layer is 0.08 μm thick.

[0050] The electron affinities of each semiconductor layer are 3.09 eV, 3.42 eV, 3.71 eV, and 4.07 eV, respectively. The incident light wavelength range is 400 nm to 900 nm.

[0051] The spectral response characteristic curve obtained from the detector simulation in Example 4 is as follows: Figure 6 As shown, compared to the detectors in Examples 1-3, the linear correlation coefficient of this detector structure is as low as 0.56 under different bias voltages.

[0052] Comparison Column 1

[0053] Incident light containing different wavelength components enters from the left end of the detector. The middle of the detector is an intrinsic layer with a band gap of Eg1 (1.36 eV).

[0054] To ensure ohmic contact between the detector and the incident and emitted electrodes, very thin, heavily doped p+ and n+ layers are respectively formed at both ends of the intrinsic layer. Each semiconductor layer is 10 μm thick, and the heavily doped layer is 0.1 μm thick. The incident light wavelength range is 400 nm to 900 nm.

[0055] The spectral response curves obtained from the detector simulation in Comparative Example 1 are as follows: Figure 7 As shown, the linear correlation coefficient of this detector structure is 0.99 under different bias voltages, and the spectral response is almost linearly correlated under different bias voltages.

[0056] The above description is merely a preferred embodiment of the present invention. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for reducing the linear correlation coefficient of a detector's spectral response, characterized in that, Different wavelengths of incident light are incident from the left electrode of the spectrometer. The light of different wavelengths is absorbed by specific regions of the multilayer energy bandgap semiconductor absorption layer. By modulating the electron affinity of the semiconductor absorption layer, the space charge density distribution of the detector and the electric field intensity are made different, which leads to the difference in the collection of photogenerated carriers generated by the incident light. Finally, the spectral response characteristics of the detector can be modulated under different bias voltages. The detector has the following structure from left to right: left electrode (1), heavily doped p+ layer (2), p-type layer (3), first intrinsic layer (4), second intrinsic layer (5), n-type layer (6), heavily doped n+ layer (7), and right electrode (8); the band gap of the semiconductor absorption layer changes from large to small, i.e., Eg1 > Eg2 > Eg3 > Eg4.

2. The method for reducing the linear correlation coefficient of the detector spectral response according to claim 1, characterized in that, The heavily doped p+ layer (2) and heavily doped n+ layer (7) have a thickness of less than 0.3 μm, which makes the detector ohmic in contact with the left electrode (1) at the incident end and the right electrode (8) at the exit end.

3. The method for reducing the linear correlation coefficient of the detector spectral response according to claim 1, characterized in that, The semiconductor absorption layer includes a p-type layer (3), a first intrinsic layer (4), a second intrinsic layer (5), and an n-type layer (6). Its electron affinity can be controlled by selecting semiconductor materials with different electron affinity, ion doping of the semiconductor material, or defect design of the semiconductor material.

4. The method for reducing the linear correlation coefficient of the detector spectral response according to claim 3, characterized in that, The semiconductor absorption layer is a bulk material with high light absorption rate covering the ultraviolet-near infrared range.

5. The method for reducing the linear correlation coefficient of the detector spectral response according to claim 4, characterized in that, The bulk materials with high light absorption rates include silicon, perovskite, quantum dots, and combinations thereof.

6. The method for reducing the linear correlation coefficient of the detector spectral response according to claim 4, characterized in that, The semiconductor absorber layer is prepared by solution epitaxy, spin coating, and spray coating.

7. The method for reducing the linear correlation coefficient of the detector spectral response according to claim 1, characterized in that, The left electrode (1) and right electrode (8) are metal electrodes or conductive oxide electrodes.

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