Heterojunction broadband polarization sensitive photoelectric detector and preparation method thereof

Abstract

The invention discloses a heterojunction broadband polarization sensitive photoelectric detector and a preparation method thereof, and belongs to the technical field of photoelectric detectors. Comprising a substrate; the two-dimensional narrow band gap material is arranged on the substrate; the two-dimensional polarization sensitive material is partially arranged above the two-dimensional narrow-band-gap material and is matched with the energy band of the two-dimensional narrow-band-gap material; the metal electrode is arranged at one end, far away from the overlapped part of the two-dimensional narrow-band-gap material and the two-dimensional polarization sensitive material; the energy band arrangement of the heterojunction is regulated and controlled by applying bias voltage to the detector, so that the energy band arrangement is converted from a type II to a type III. III-type energy band arrangement obtained through II-type conversion can effectively separate, transmit and collect photon-generated carriers under the condition that the III-type energy band arrangement is not affected by heterojunction interface potential barriers, and therefore the responsivity is remarkably improved. And part of photo-induced electrons are transmitted between the two materials through an inter-band tunneling mechanism, so that the response speed is improved on the basis of improving the responsivity.

Description

Technical Field

[0001] This invention belongs to the field of photodetector technology, specifically relating to a heterojunction broadband polarization-sensitive photodetector and its fabrication method. Background Technology

[0002] In recent years, with the increasing demand for broadband, multifunctional, high-response, fast-response, and miniaturized photodetectors, two-dimensional materials, with their diverse types, full bandgap coverage, and absence of dangling bonds, have become excellent candidate materials for broadband polarization-sensitive photodetectors. Van der Waals heterostructures constructed from two-dimensional materials can not only fully utilize the unique properties of the constituent materials but also enhance detection performance through ingenious bandgap design. Three typical bandgap arrangements are straddle (Type I), staggered (Type II), and staggered (Type III). In Type I bandgap arrangements, photogenerated carriers are confined within the same material, which is conducive to radiative recombination and therefore suitable for light-emitting devices. In contrast, Type II bandgap arrangements (unaffected by interface barriers) facilitate efficient carrier separation, thus significantly improving responsivity and making them very suitable for photodetector applications, but with limited response speed. As for Type III bandgap arrangements, the bands do not overlap, leading to low photogenerated carrier transport efficiency and consequently, lower photodetector responsivity. However, the cooperative tunneling effect can significantly improve the response speed. Clearly, it is difficult to achieve both high responsivity and high response speed with a single type of band arrangement. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem in the prior art that heterojunction photodetectors made of two-dimensional materials cannot simultaneously achieve high responsivity and high response speed due to the single type of band arrangement. The invention provides a heterojunction broadband polarization-sensitive photodetector with bias voltage-controlled band arrangement and its fabrication method.

[0005] A heterojunction broadband polarization-sensitive photodetector, wherein on a substrate, the left end of a two-dimensional polarization material is placed on the right end of a two-dimensional narrow bandgap material, and the two partially overlap to form a junction region;

[0006] Metal electrodes are respectively provided at the left end of the two-dimensional narrow bandgap material and the right end of the two-dimensional polarization material;

[0007] The two-dimensional narrow bandgap material is matched with the energy band of the two-dimensional polarization material;

[0008] Both the narrow bandgap material layer and the polarization-sensitive material layer have a thickness of 10-100 nm; the metal electrode has a thickness of 10-20 / 50-100 nm and a junction area of ​​20-150 μm. 2 ;

[0009] The substrate is SiO2 / Si, and the metal electrode is a Ti / Au metal electrode;

[0010] By applying a bias voltage to the heterojunction broadband polarization-sensitive photodetector, the band arrangement can be controlled, causing a transition from type II to type III band arrangement.

[0011] The narrow bandgap material is Bi2Te3, Bi2Se3, PtSe2, or Sb2Te3;

[0012] The two-dimensional polarizing material is GeSe, GeTe, ReS2, or ReSe2;

[0013] The narrow bandgap material is Bi2Te3, and the two-dimensional polarization material is GeSe;

[0014] The Bi2Te3 material layer has a thickness of 76 nm, and the GeSe layer has a thickness of 57 nm; the junction area is 39 μm. 2 The thickness of the Ti / Au metal electrode is 15 / 80 nm.

[0015] The narrow bandgap material is Bi2Te3 and the two-dimensional polarization material is GeTe; or the narrow bandgap material is Bi2Se3 and the two-dimensional polarization material is ReSe2; or the narrow bandgap material is PtSe2 and the two-dimensional polarization material is ReS2; or the narrow bandgap material is Sb2Te3 and the two-dimensional polarization material is ReS2.

[0016] The method for fabricating a heterojunction-type broadband polarization-sensitive photodetector is characterized by comprising the following steps:

[0017] a. Prepare the substrate, clean it with acetone, isopropanol and deionized water respectively, and dry the substrate with a nitrogen gun;

[0018] b. Transfer the two-dimensional narrow bandgap material onto the substrate from step a;

[0019] c. A portion of the transferred two-dimensional polarized material is placed above a two-dimensional narrow bandgap material to form a junction region;

[0020] d. Prepare metal electrodes.

[0021] This invention provides a heterojunction-type broadband polarization-sensitive photodetector and its fabrication method, wherein the band arrangement can be transformed from type II to type III by an applied forward bias voltage. The type III band arrangement obtained by the type II transformation can effectively separate, transport, and collect photogenerated carriers without being affected by the heterojunction interface barrier, thereby significantly improving responsivity. Simultaneously, some photogenerated electrons are transported between the two materials through interband tunneling (BTBT) mechanism, further improving the response speed on top of the improved responsivity.

[0022] The heterojunction broadband polarization-sensitive photodetector of the present invention uses a two-dimensional narrow bandgap material (such as Bi2Te3, Bi2Se3, PtSe2 or Sb2Te3, etc.) as the light absorber in the near-infrared band of the detector, and uses a two-dimensional polarization material (such as GeSe, GeTe, ReS2 or ReSe2, etc.) that matches the bandgap of the two-dimensional narrow bandgap material to introduce polarization photodetector capability into the detector, thereby fabricating a heterojunction photodetector that meets the requirements of miniaturization, broadband, and high-precision detection.

[0023] The heterojunction broadband polarization-sensitive photodetector of the present invention, by applying a specific bias voltage, causes the energy band arrangement of the detector to change from type II to type III. This effectively utilizes the fact that charge carriers in the type II energy band arrangement can be effectively separated, transported and collected without being affected by the interface potential barrier, thereby significantly improving the responsivity. It also effectively utilizes the interband tunneling (BTBT) mechanism of charge carriers through the heterojunction interface, ultimately achieving an improvement in responsivity and response speed.

[0024] Based on the ingenious bandgap design and the synergistic effect of the BTBT process, this invention shows an interesting prospect for developing high-performance broadband polarization-sensitive photodetectors. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the fabrication process of the heterojunction-based broadband polarization-sensitive photodetector based on Bi2Te3 / GeSe of the present invention.

[0026] Figure 2 This is a schematic diagram showing the band arrangement of Bi2Te3 and GeSe before and after contact, as well as the band arrangement after adjustment by bias voltage.

[0027] Figure 3 This is a flowchart illustrating the fabrication process of a heterojunction-based broadband polarization-sensitive photodetector based on Bi2Te3 / GeTe.

[0028] Figure 4 This is a flowchart illustrating the fabrication process of a heterojunction broadband polarization-sensitive photodetector based on Bi2Se3 / ReSe2.

[0029] Figure 5 This is a flowchart illustrating the fabrication process of a heterojunction-based broadband polarization-sensitive photodetector based on PtSe2 / ReS2.

[0030] Figure 6 This is a flowchart illustrating the fabrication process of a heterojunction broadband polarization-sensitive photodetector based on Sb2Te3 / ReS2.

[0031] Figure 7 The figure shows the characterization results of the heterojunction broadband polarization-sensitive photodetector based on Bi2Te3 / GeSe prepared in Example 1 of this invention. Detailed Implementation

[0032] Example 1: Heterojunction Broadband Polarization-Sensitive Photodetector Based on Bi2Te3 / GeSe

[0033] The fabrication flowchart of the heterojunction broadband polarization-sensitive photodetector based on Bi2Te3 / GeSe of this invention is shown below. Figure 1 This includes the following steps:

[0034] Step a: Prepare SiO2 / Si substrate

[0035] Prepare a P++ / SiO2 substrate with a 285 nm thick SiO2, clean it with acetone, isopropanol and deionized water respectively, and then dry the substrate with a nitrogen gun.

[0036] Step b: Transfer Bi2Te3 material

[0037] Bi2Te3 material was transferred onto the substrate in step a using a dry transfer method;

[0038] The thickness of the Bi2Te3 material layer in this invention is 76 nm;

[0039] Step c: Prepare GeSe material on Bi2Te3 material

[0040] GeSe material was transferred using a dry transfer method, with a portion of it placed on top of Bi2Te3 material;

[0041] The overlap region (i.e., junction region) between the Bi2Te3 and GeSe materials in this invention is 39 μm. 2 .

[0042] The thickness of the GeSe material layer in this invention is 57 nm;

[0043] Step d: Photolithography and Development

[0044] Photolithography and development are performed on the Bi2Te3 material and the GeSe material at the ends away from their overlapping portion;

[0045] The photolithography steps are as follows:

[0046] 1. Spreading: Low speed stage 100-1000 r / s, 2-15 s; High speed stage 1000-4000 r / s, 10-40 s;

[0047] 2. Pre-baking: 80-150℃, 60-150 s;

[0048] 3. Photolithography: Exposure time 2-12 s;

[0049] The developing step takes 30-120 seconds.

[0050] Step e: Coating and adhesive removal (lift-off)

[0051] Coating: Ti / Au metal electrodes were deposited using thermal evaporation.

[0052] Degumming: Soak in acetone for 2-8 hours;

[0053] The thickness of the Ti / Au metal electrode of the present invention can be in the range of 10-20 / 50-100 nm, and the thickness of the Ti / Au metal electrode in this embodiment is 15 / 80 nm.

[0054] Step f: Adjust the bias voltage to control the band arrangement of the heterojunction detector prepared in step e. See the results below. Figure 2 ; Figure 2 This is a schematic diagram illustrating the band alignment between Bi₂Te₃ and GeSe controlled by bias voltage. According to previous literature, Bi₂Te₃ and GeSe form a type II band alignment (…). Figure 2 (a) Since the Fermi level of GeSe is higher than that of Bi₂Te₃, once the two materials come into contact, electrons from GeSe will enter Bi₂Te₃, eventually reaching an equilibrium state. Figure 2 (b) When the drain Bi2Te3 of the device is reverse biased (-1.2V), the band bend increases, and the band arrangement changes from type II to type I. Figure 2 (c) When the drain Bi2Te3 of the device is forward biased (+1.2V), the band reversal occurs, as shown in the image. Figure 2 As shown in (d), the band arrangement changes from type II to type III. At this point, the photogenerated carriers generated in Bi₂Te₃ and GeSe easily separate without the obstruction of an interface barrier. Photogenerated electrons (photogenerated holes) enter n-Bi₂Te₃ (p-GeSe) and are easily collected by the drain (source) under the influence of the net electric field. Furthermore, some electrons in GeSe tunnel into Bi₂Te₃ through the BTBT process, which is expected to further improve the device's response speed.

[0055] Figure 7 The image shows the characterization results of the heterojunction broadband polarization-sensitive photodetector based on Bi₂Te₃ / GeSe fabricated in Example 1. This device generates photocurrent in the 532-1550 nm range. Figure 7 (a)), where the highest responsivity is 5.86 × 10⁻⁶. 3 A / W ( Figure 7 (b)). According to Figure 7 The fitting results in (c) show that some electrons in GeSe tunnel into Bi2Te3 through the BTBT process, which helps to further improve the detector's response speed, with the fastest response time being 19 μs. Figure 7 (d)). This polarization-sensitive photodetector achieves an anisotropy ratio of 2.08 at 808 nm. Figure 7 (e)), and can achieve polarization imaging ( Figure 7 (f) improves its target recognition capability in complex environments.

[0056] Example 2: Heterojunction Broadband Polarization-Sensitive Photodetector Based on Bi2Te3 / GeTe

[0057] The fabrication flowchart of the heterojunction broadband polarization-sensitive photodetector based on Bi2Te3 / GeTe of this invention is shown below. Figure 3 This includes the following steps:

[0058] Step a: Prepare SiO2 / Si substrate

[0059] Prepare a P++ / SiO2 substrate with a 285 nm thick SiO2, clean it with acetone, isopropanol and deionized water respectively, and then dry the substrate with a nitrogen gun.

[0060] Step b: Transfer Bi2Te3 material

[0061] Bi2Te3 material was transferred onto the substrate in step a using a dry transfer method;

[0062] In this embodiment, the thickness of the Bi2Te3 material layer is 10 nm;

[0063] Step c: Prepare GeTe material on Bi2Te3 material

[0064] GeTe material was transferred using a dry transfer method, with a portion of it placed on top of Bi2Te3 material;

[0065] In this embodiment, the overlapping area (i.e., the junction region) of the Bi2Te3 and GeTe materials is 20 μm. 2 ;

[0066] The thickness of the GeTe material layer in this embodiment is 10 nm;

[0067] Step d: Photolithography and Development

[0068] Photolithography and development are performed on the Bi2Te3 material and the GeTe material at the ends away from their overlapping portion;

[0069] The photolithography steps are as follows:

[0070] 1. Spreading: Low speed stage 100-1000 r / s, 2-15 s; High speed stage 1000-4000 r / s, 10-40 s;

[0071] 2. Pre-baking: 80-150 ℃, 60-150 s;

[0072] 3. Photolithography: Exposure time 2-12 s;

[0073] The developing step takes 30-120 seconds.

[0074] Step e: Coating and adhesive removal (lift-off)

[0075] Coating: Ti / Au metal electrodes were deposited using thermal evaporation.

[0076] Degumming: Soak in acetone for 2-8 hours;

[0077] In this embodiment, the thickness of the Ti / Au metal electrode is 10 / 50 nm.

[0078] Step f: By changing the bias voltage, the band arrangement of the heterojunction-based broadband polarization-sensitive photodetector prepared in step e is controlled, and the band arrangement undergoes a type II to type III transition.

[0079] Example 3: Heterojunction Broadband Polarization-Sensitive Photodetector Based on Bi2Se3 / ReSe2

[0080] The fabrication flowchart of the heterojunction broadband polarization-sensitive photodetector based on Bi2Se3 / ReSe2 of this invention is shown below. Figure 4 This includes the following steps:

[0081] Step a: Prepare SiO2 / Si substrate

[0082] Prepare a P++ / SiO2- substrate with a 285nm thick SiO2, clean it with acetone, isopropanol and deionized water respectively, and then dry the substrate with a nitrogen gun.

[0083] Step b: Transfer Bi2Se3 material

[0084] Bi2Se3 material was transferred onto the substrate in step a using a dry transfer method;

[0085] The thickness of the Bi2Se3 material layer in this embodiment is 100 nm;

[0086] Step c: Prepare ReSe2 material on Bi2Se3 material

[0087] ReSe2 material was transferred using a dry transfer method, with a portion of it placed on top of Bi2Se3 material.

[0088] In this embodiment, the overlapping area (i.e., the junction region) of the Bi2Se3 and ReSe2 materials is 150 μm. 2 ;

[0089] In this embodiment, the thickness of the ReSe2 material layer is 100 nm;

[0090] Step d: Photolithography and Development

[0091] Photolithography and development are performed on the Bi2Se3 material and the ReSe2 material at the ends away from their overlapping portion;

[0092] The photolithography steps are as follows:

[0093] 1. Spreading: Low speed stage 100-1000 r / s, 2-15 s; High speed stage 1000-4000 r / s, 10-40 s;

[0094] 2. Pre-baking: 80-150 ℃, 60-150 s;

[0095] 3. Photolithography: Exposure time 2-12 s;

[0096] The developing step takes 30-120 seconds.

[0097] Step e: Coating and adhesive removal (lift-off)

[0098] Coating: Ti / Au metal electrodes were deposited using thermal evaporation.

[0099] Degumming: Soak in acetone for 2-8 hours;

[0100] In this embodiment, the thickness of the Ti / Au metal electrode is 20 / 100 nm.

[0101] Step f: By changing the bias voltage, the band arrangement of the heterojunction broadband polarization-sensitive photodetector based on Bi2Se3 / ReSe2 prepared in step e is adjusted, and the band arrangement undergoes a type II to type III transition.

[0102] Example 4: Heterojunction Broadband Polarization-Sensitive Photodetector Based on PtSe2 / ReS2

[0103] The fabrication flowchart of the heterojunction broadband polarization-sensitive photodetector based on PtSe2 / ReS2 of this invention is shown below. Figure 5 This includes the following steps:

[0104] Step a: Prepare SiO2 / Si substrate

[0105] Prepare a P++ / SiO2 substrate with a 285nm thick SiO2, clean it with acetone, isopropanol and deionized water respectively, and then dry the substrate with a nitrogen gun.

[0106] Step b: Transfer PtSe2 material

[0107] PtSe2 material was transferred onto the substrate in step a using a dry transfer method;

[0108] In this embodiment, the thickness of the PtSe2 material layer is 35 nm;

[0109] Step c: Prepare ReS2 material on PtSe2 material

[0110] ReS2 material was transferred using a dry transfer method, with a portion of it placed on top of PtSe2 material.

[0111] In this embodiment, the overlapping area (i.e., the junction region) of the PtSe2 and ReS2 materials is 140 μm. 2 ;

[0112] In this embodiment, the ReS2 material layer thickness is 60 nm;

[0113] Step d: Photolithography and Development

[0114] Photolithography and development are performed on the PtSe2 material and the ReS2 material at the ends away from their overlapping portion;

[0115] The photolithography steps are as follows:

[0116] 1. Spreading: Low speed stage 100-1000 r / s, 2-15 s; High speed stage 1000-4000 r / s, 10-40 s;

[0117] 2. Pre-baking: 80-150℃, 60-150 s;

[0118] 3. Photolithography: Exposure time 2-12 s;

[0119] The developing step takes 30-120 seconds.

[0120] Step e: Coating and adhesive removal (lift-off)

[0121] Coating: Ti / Au metal electrodes were deposited using thermal evaporation.

[0122] Degumming: Soak in acetone for 2-8 hours;

[0123] In this embodiment, the thickness of the Ti / Au metal electrode is 10 / 90 nm.

[0124] Step f: By changing the bias voltage, the band arrangement of the heterojunction broadband polarization-sensitive photodetector based on PtSe2 / ReS2 prepared in step e is adjusted, and the band arrangement undergoes a type II to type III transition.

[0125] Example 5: Heterojunction Broadband Polarization-Sensitive Photodetector Based on Sb2Te3 / ReS2

[0126] The fabrication flowchart of the heterojunction broadband polarization-sensitive photodetector based on Sb2Te3 / ReS2 of this invention is shown below. Figure 6 This includes the following steps:

[0127] Step a: Prepare SiO2 / Si substrate

[0128] Prepare a P++ / SiO2 substrate with a 285 nm thick SiO2, clean it with acetone, isopropanol and deionized water respectively, and then dry the substrate with a nitrogen gun.

[0129] Step b: Transfer Sb2Te3 material

[0130] Sb2Te3 material was transferred onto the substrate in step a using a dry transfer method.

[0131] In this embodiment, the thickness of the Sb2Te3 material layer is 20 nm;

[0132] Step c: Prepare ReS2 material on Sb2Te3 material

[0133] ReS2 material was transferred using a dry transfer method, and part of it was placed on top of Sb2Te3 material.

[0134] The overlap region (i.e., the junction region) between the Sb2Te3 and ReS2 materials is 90 μm. 2 ;

[0135] The thickness of the ReS2 material layer is 80 nm;

[0136] Step d: Photolithography and Development

[0137] Photolithography and development are performed on the Sb2Te3 material and the ReS2 material at the ends away from their overlapping portion;

[0138] The photolithography steps are as follows:

[0139] 1. Spreading: Low speed stage 100-1000 r / s, 2-15 s; High speed stage 1000-4000 r / s, 10-40 s;

[0140] 2. Pre-baking: 80-150 ℃, 60-150 s;

[0141] 3. Photolithography: Exposure time 2-12 s;

[0142] The developing step takes 30-120 seconds.

[0143] Step e: Coating and adhesive removal (lift-off)

[0144] Coating: Ti / Au metal electrodes were deposited using thermal evaporation.

[0145] Remove glue: Soak in acetone for 2-8 hours.

[0146] In this embodiment, the thickness of the Ti / Au metal electrode is 20 / 70 nm.

[0147] Step f: By changing the bias voltage, the band arrangement of the heterojunction broadband polarization-sensitive photodetector based on Sb2Te3 / ReS2 prepared in step e is adjusted, and the band arrangement undergoes a type II to type III transition.

Claims

1. A heterojunction-type broadband polarization-sensitive photodetector, characterized in that: On the substrate, the left end of the two-dimensional polarization material overlaps the right end of the two-dimensional narrow bandgap material, forming a junction region. Metal electrodes are respectively provided at the left end of the two-dimensional narrow bandgap material and the right end of the two-dimensional polarization material; The energy bands of the two-dimensional narrow bandgap material are matched with those of the two-dimensional polarization material.

2. The heterojunction broadband polarization-sensitive photodetector according to claim 1, characterized in that: Both the narrow bandgap material layer and the polarization-sensitive material layer have a thickness of 10-100 nm; the metal electrode has a thickness of 10-20 / 50-100 nm and a junction area of ​​20-150 μm. 2 .

3. A heterojunction broadband polarization-sensitive photodetector according to claim 2, characterized in that: The substrate is SiO2 / Si, and the metal electrode is a Ti / Au metal electrode.

4. A heterojunction broadband polarization-sensitive photodetector according to claim 3, characterized in that: By applying a bias voltage to the heterojunction broadband polarization-sensitive photodetector, the band arrangement can be controlled, causing a transition from type II to type III band arrangement.

5. A heterojunction broadband polarization-sensitive photodetector according to claim 1, 2, 3 or 4, characterized in that: The narrow bandgap material is Bi2Te3, Bi2Se3, PtSe2 or Sb2Te3.

6. A heterojunction broadband polarization-sensitive photodetector according to claim 5, characterized in that: The two-dimensional polarizing material is GeSe, GeTe, ReS2, or ReSe2.

7. A heterojunction broadband polarization-sensitive photodetector according to claim 6, characterized in that: The narrow bandgap material is Bi2Te3, and the two-dimensional polarization material is GeSe.

8. A heterojunction broadband polarization-sensitive photodetector according to claim 7, characterized in that: The Bi2Te3 material layer has a thickness of 76 nm, and the GeSe layer has a thickness of 57 nm; the junction area is 39 μm. 2 The thickness of the Ti / Au metal electrode is 5 / 80 nm.

9. A heterojunction broadband polarization-sensitive photodetector according to claim 6, characterized in that: The narrow bandgap material is Bi2Te3 and the two-dimensional polarization material is GeTe; or the narrow bandgap material is Bi2Se3 and the two-dimensional polarization material is ReSe2; or the narrow bandgap material is PtSe2 and the two-dimensional polarization material is ReS2; or the narrow bandgap material is Sb2Te3 and the two-dimensional polarization material is ReS2.

10. The method for fabricating a heterojunction broadband polarization-sensitive photodetector according to claim 1, characterized in that, Includes the following steps: a. Prepare the substrate, clean it with acetone, isopropanol and deionized water respectively, and dry the substrate with a nitrogen gun; b. Transfer the two-dimensional narrow bandgap material onto the substrate from step a; c. A portion of the transferred two-dimensional polarized material is placed above a two-dimensional narrow bandgap material to form a junction region; d. Prepare metal electrodes.

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