A bipolar circularly polarized light detector and its preparation method

Abstract

The present invention discloses a bipolar circularly polarized light detector and a preparation method thereof, which relates to the field of photoelectric detectors. The bipolar circularly polarized light detector comprises a first electrode layer and a second electrode layer respectively arranged on both sides of a photosensitive layer; the first electrode layer and the second electrode layer are mutually chiral structures. The present invention places hollow left-handed and right-handed nanoarrays at the upper and lower ends of the photosensitive layer respectively. Under LCP incidence, a stronger light field is generated at the left-handed nanoarray, and under RCP incidence, a stronger light field is generated at the right-handed nanoarray. Due to the differentiated distribution of the light field intensity, based on the Danby effect, an opposite built-in electric field is generated, and then a photocurrent in the opposite direction is generated. This solves the current high requirements of circularly polarized photodetectors for the accuracy of incident light power.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric detectors, in particular to a bipolar circularly polarized light detector and a preparation method thereof. Background Art

[0002] Circularly polarized light detectors have been widely used in biosensing, molecular detection, and circular dichroism spectroscopy, showing extraordinary versatility and precision. In addition, circularly polarized light detectors have also been used in advanced fields such as optical communications, imaging technology, and quantum computing, highlighting their broad potential in various disciplines. At present, the method of circularly polarized light detection is mainly to distinguish and detect left-handed circularly polarized light by using chiral materials or structures, such as chiral hybrid perovskites and chiral metasurfaces, to detect the currents of different sizes caused by the differential absorption of left-handed circularly polarized light (LCP) and right-handed circularly polarized light (RCP). However, this method often has high requirements on the accuracy of the incident light power. For example, the absorption rate of the left-handed structure device to LCP is higher than that to RCP, resulting in a higher photocurrent under LCP incidence than under RCP incidence at the same power. However, if the incident light power of RCP is slightly higher than that of LCP, it is possible that the photocurrent of RCP is greater than that of LCP, which leads to an erroneous judgment.

[0003] Therefore, a new method for distinguishing and detecting LCP and RCP is needed to solve the current high requirements of circular polarization photodetectors on the accuracy of incident light power. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is how to solve the problem that the current circularly polarized light detector has a high accuracy rate for incident light.

[0006] To solve the above technical problems, in a first aspect, the present invention provides the following technical solutions: a bipolar circularly polarized light detector, comprising a first electrode layer and a second electrode layer respectively arranged on both sides of a photosensitive layer; the first electrode layer and the second electrode layer are mutually chiral structures.

[0007] As a preferred solution of the bipolar circularly polarized light detector of the present invention, the first electrode layer is a right-handed structure, and the second electrode layer is a left-handed structure.

[0008] As a preferred solution of the bipolar circularly polarized light detector of the present invention, the first electrode layer is a left-handed structure, and the second electrode layer is a right-handed structure.

[0009] As a preferred solution of the bipolar circularly polarized light detector described in the present invention, the first electrode layer and the second electrode layer each have a first channel parallel to their respective length directions and a second channel intersecting with the first channel, and the angle between the first channel and the second channel is not equal to ninety degrees.

[0010] As a preferred solution of the bipolar circularly polarized light detector of the present invention, the widths of the first channel and the second channel are both 40-60 nm, and the length of the second channel is 150-250 nm.

[0011] As a preferred solution of the bipolar circularly polarized light detector of the present invention, the thickness of the first electrode layer and the second electrode layer is 15-25 nm, and the length is 3-10 μm.

[0012] As a preferred solution of the bipolar circularly polarized light detector of the present invention, the material of the photosensitive layer is indium arsenide with a thickness of 90-110 nm, and the materials of the first electrode layer and the second electrode layer are silver.

[0013] As a preferred solution of the bipolar circularly polarized light detector of the present invention, a first insulating layer and a second insulating layer are respectively arranged on a side of the first electrode layer away from the photosensitive layer and a side of the second electrode layer away from the photosensitive layer.

[0014] As a preferred solution of the bipolar circularly polarized light detector of the present invention, the material of the first insulating layer and the second insulating layer is silicon nitride, and the thickness is 200-240 nm.

[0015] In a second aspect, the present invention also provides a method for preparing a bipolar circularly polarized light detector, which is suitable for preparing the above-mentioned bipolar circularly polarized light detector, including forming a first electrode layer and a second electrode layer with mutually chiral structures on both sides of the photosensitive layer.

[0016] The beneficial effects of the present invention are as follows: the present invention places hollow left-handed and right-handed nanoarrays at the upper and lower ends of the photosensitive layer, respectively. Under LCP incidence, a stronger light field is generated at the left-handed nanoarray, and under RCP incidence, a stronger light field is generated at the right-handed nanoarray. Due to the differentiated distribution of the light field intensity, based on the Danby effect, an opposite built-in electric field is generated, thereby generating a photocurrent in the opposite direction. This solves the current high requirements of circularly polarized photodetectors for the accuracy of incident light power. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 Schematic diagram of the structure of a bipolar circularly polarized light detector.

[0019] Figure 2 is a top view of the first electrode layer.

[0020] Figure 3 is a top view of the second electrode layer.

[0021] Figure 4 This is a curve diagram showing the relationship between the device's absorptivity and wavelength under left-handed circularly polarized light incidence.

[0022] Figure 5 This is a curve diagram showing the relationship between the device's absorbance and wavelength under right-handed circularly polarized light incidence.

[0023] Figure 6 This is the spectrum of the photosensitive layer under left-handed circularly polarized light.

[0024] Figure 7 This is the spectrum of the photosensitive layer under right-handed circularly polarized light.

[0025] Figure 8 The incident power is 100 W / cm 2 The relationship between the current and wavelength of the device when left-handed circularly polarized light and right-handed circularly polarized light are incident.

[0026] Fig. 9 The incident power is 100 W / cm 2 The relationship between the device's responsivity and wavelength when left-handed circularly polarized light and right-handed circularly polarized light are incident.

[0027] Fig.10 The graph is a relationship between the current size and wavelength of the device under left-handed circularly polarized light and right-handed circularly polarized light when the incident power is different.

[0028] Fig.11 To verify θ under left-handed circularly polarized light incidence 1 (θ 2 ) and W robustness diagram.

[0029] Fig.12 To verify θ under right-handed circularly polarized light incidence 1 (θ 2 ) and W robustness diagram.

[0030] In the figure: 1, photosensitive layer; 2, first electrode layer; 21, first channel; 22, second channel; 3, second electrode layer; 4, first insulating layer; 5, second insulating layer. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0034] Reference Figure 1 , which is the first embodiment of the present invention, provides a bipolar circularly polarized light detector. The bipolar circularly polarized light detector includes a photosensitive layer 1, a first electrode layer 2 and a second electrode layer 3.

[0035] Specifically, the bipolar circularly polarized light detector includes, from bottom to top, a first insulating layer 4 , a first electrode layer 2 , a photosensitive layer 1 , a second electrode layer 3 and a second insulating layer 5 .

[0036] The first electrode layer 2 and the second electrode layer 3 are hollow chiral structures and are respectively located on both sides of the photosensitive layer 1. The photosensitive layer 1 fills the hollow gap between the first electrode layer 2 and the second electrode layer 3. A load is connected between the first electrode layer 2 and the second electrode layer 3.

[0037] Better, refer to Figure 2 and Figure 3 The structure of the first electrode layer 2 and the second electrode layer 3 has a first channel 21 parallel to the length direction thereof and a second channel 22 intersecting the first channel 21, and the angle between the first channel 21 and the second channel 22 is not equal to ninety degrees. In this embodiment, the first channel 21 is located in the middle of the first electrode layer 2 and the second electrode layer 3, and the angle between the first channel 21 and the second channel 22 is 45°. The widths of the first channel 21 and the second channel 22 are both 40-60 nm, and the length of the second channel 22 is 150-250 nm.

[0038] Preferably, the first electrode layer 2 and the second electrode layer 3 have a thickness of 15-25 nm, a length of 3-10 μm, a period of 200 nm, and are made of silver.

[0039] Preferably, the material of the photosensitive layer 1 is indium arsenide, with a thickness of 90-110 nm. The material of the first insulating layer 4 and the second insulating layer 5 is silicon nitride, with a thickness of 200-240 nm.

[0040] As an optional embodiment, the first electrode layer 2 may be a right-handed structure, and the second electrode layer 3 may be a left-handed structure.

[0041] As an optional embodiment, the first electrode layer 2 may be a left-handed structure, and the second electrode layer 3 may be a right-handed structure.

[0042] As an optional embodiment, the present invention also provides a method for preparing a bipolar circularly polarized light detector, the preparation method comprising:

[0043] Step 1: Form the first insulating layer 4 by physical vapor deposition, the material is Si 3 N 4 , thickness is 200 nm;

[0044] Step 2: depositing a layer of Ag material with a thickness of 20 nm on the first insulating layer 4, and then etching a right-handed metal nanoarray structure by electron beam etching to form a first electrode layer 2;

[0045] Step 3: growing a photosensitive layer on the first electrode layer 2, the material of which is InAs, with a thickness of 80 nm, and filling the electrode hollowing;

[0046] Step 4: depositing a layer of Ag material again by physical vapor deposition with a thickness of 20 nm, and then etching out a left-handed metal nanoarray structure by electron beam etching to form a second electrode layer 3;

[0047] Step Five: Growing InAs in the second electrode layer 3 hollow, so that the photosensitive layer thickness reaches 100nm;

[0048] Step 6: Form a second insulating layer 5 by physical vapor deposition, the material of which is Si 3 N 4 , with a thickness of 200nm.

[0049] After the preparation is completed, the absorption spectrum of the device under LCP incidence can be obtained, such as Figure 4 As shown. Figure 4 It can be seen that under LCP incidence, the device has high absorption in the band of 2500~3500nm, the absorption rate exceeds 0.45, and reaches a maximum value of 0.5 at 3100nm.

[0050] Then, the absorption spectrum of the device under RCP incidence is obtained, such as Figure 5 As shown. Figure 5 It can be found that under RCP incidence, the device also has high absorption in the 2500~3500nm band, the absorption rate exceeds 0.6, and has a maximum value of 0.83 at 2500nm. It can be found that the device's absorption of RCP is higher than that of LCP.

[0051] Then, the light field distribution diagram of the photosensitive layer of the device under LCP incidence was obtained, such as Figure 6 As shown. Figure 6 It can be found that when the device is incident with LCP, the light field intensity above the photosensitive layer 1 is greater than that below.

[0052] Then, the light field distribution diagram of the photosensitive layer 1 under RCP incident on the device was calculated, as shown in Figure 7 As shown. Figure 7 It can be found that when the device is incident on RCP, the light field intensity below the photosensitive layer 1 is greater than that above. Figure 6 Almost the opposite.

[0053] Then, we measured the device at an incident power of 100 W / cm 2 When , the current magnitude of the device under LCP and RCP incidence. Figure 8 As shown, it can be seen that under LCP incidence, the current magnitude of the device is negative, and under RCP incidence, the current magnitude of the device is positive, which can intuitively distinguish LCP and RCP.

[0054] The device responsivity is an important indicator of device performance. We calculated the device's responsivity at an incident power of 100 W / cm 2 When , the responsivity (R) of the device under LCP and RCP incidence is as follows: Fig. 9 shown.

[0055] R=I / P

[0056] Where I is the magnitude of the response current under incident light, and P is the incident light power. Fig. 9 It can be found that the device responsivity is 10 4 This is an extremely high responsivity in the field of circularly polarized photodetectors, proving that the device has excellent performance.

[0057] In order to verify that the current direction of the device is opposite under LCP and RCP incident conditions at different optical powers, we measured the current size of the device under LCP and RCP incident conditions at different power incident conditions, such as Fig.10As shown in the figure, it can be found that although the optical power has changed, the current of the device is negative under LCP incidence, and positive under RCP incidence. Therefore, we have solved the important problem that circular polarization photodetectors have high requirements for the accuracy of incident light power.

[0058] The robustness of the device has always been a concern, so we measured the angle θ between the first channel 21 and the second channel 22 of the device when LCP was incident. 1 (θ 2 ) and the robustness of the channel width W, such as Fig.11 It can be seen that when LCP is incident, the angle θ between the first channel 21 and the second channel 22 is 1 (θ 2 ) When the angle is between 40 and 50 degrees and the channel width W changes from 10nm to 50nm, the photocurrent is negative, which shows good robustness. At the same time, we also measured the θ 1 (θ 2 ) and W, it can be found that the photocurrent of the device is almost positive, which has good robustness.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A bipolar circularly polarized light detector, characterized in that: It comprises a first electrode layer (2) and a second electrode layer (3) respectively arranged on both sides of the photosensitive layer (1); The first electrode layer (2) and the second electrode layer (3) have mutually chiral structures; The first electrode layer (2) and the second electrode layer (3) each have a first channel (21) parallel to their respective length directions and a second channel (22) intersecting the first channel (21), and the angle between the first channel (21) and the second channel (22) is not equal to ninety degrees; The bipolar circularly polarized light detector generates currents in opposite directions when irradiated by left-handed circularly polarized light and right-handed circularly polarized light.

2. The bipolar circularly polarized light detector according to claim 1, characterized in that: The first electrode layer (2) is a right-handed structure, and the second electrode layer (3) is a left-handed structure.

3. The bipolar circularly polarized light detector according to claim 2, characterized in that: The first electrode layer (2) is a left-handed structure, and the second electrode layer (3) is a right-handed structure.

4. The bipolar circularly polarized light detector according to claim 3, characterized in that: The width of the first channel (21) and the second channel (22) are both 40-60 nm, and the length of the second channel (22) is 150-250 nm.

5. The bipolar circularly polarized light detector according to claim 4, characterized in that: The first electrode layer (2) and the second electrode layer (3) have a thickness of 15-25 nm and a length of 3-10 μm.

6. The bipolar circularly polarized light detector according to claim 5, characterized in that: The material of the photosensitive layer (1) is indium arsenide, with a thickness of 90-110 nm, and the material of the first electrode layer (2) and the second electrode layer (3) is silver.

7. The bipolar circularly polarized light detector according to claim 6, characterized in that: A first insulating layer (4) and a second insulating layer (5) are respectively arranged on a side of the first electrode layer (2) away from the photosensitive layer (1) and on a side of the second electrode layer (3) away from the photosensitive layer (1).

8. The bipolar circularly polarized light detector according to claim 7, characterized in that: The material of the first insulating layer (4) and the second insulating layer (5) is silicon nitride, and the thickness is 200-240 nm.

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