Bismuth telluride / bismuth oxygen selenium heterojunction photoelectric detector and preparation method thereof

Abstract

The invention discloses a bismuth telluride / bismuth oxygen selenium heterojunction photoelectric detector and a preparation method thereof, and belongs to the technical field of preparation of semiconductor materials and photoelectric detectors. According to the invention, Bi2Te3 and Bi2O2Se, which are grown by a chemical vapor deposition method, are vertically stacked together through an improved two-dimensional material transfer process, so that the Bi2Te3 / Bi2O2Se heterojunction is formed. A Bi2Te3 layer and a Bi2O2Se layer are deposited on the surface of the Bi2Te3 layer, then gold electrodes are deposited on the Bi2Te3 layer and the Bi2O2Se layer through electron beam evaporation, the two-end photoelectric detector is prepared, compared with a Bi2O2Se-based photoelectric detector, the dark current of the prepared detector is reduced by one order of magnitude, the responsivity and the specific detection rate are improved by one order of magnitude, the switch ratio is improved by 100 times, and the photoelectric detection performance is comprehensively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor materials and optoelectronic detector preparation, and particularly relates to a bismuth telluride / bismuth oxy selenide heterojunction optoelectronic detector and a preparation method thereof. Background Art

[0002] In recent years, Bi 2 O 2 Se has emerged as a two-dimensional semiconductor material with excellent performance. It not only has excellent air stability but also has an ultra-high carrier mobility (exceeding 20000 cm 2 V -1 s -1 ) at 2K, which makes it applicable to high-speed and low-power optoelectronic detector applications. However, the high mobility easily causes a relatively high dark current, simultaneously reducing the on-off ratio of the detector, increasing the static power consumption of a single optoelectronic detector, and restricting the application of array and integrated optoelectronic detectors. Therefore, suppressing the excessively high dark current of Bi 2 O 2 Se-based optoelectronic detectors is the key to their application.

[0003] Individual Bi 2 O 2 Se material detectors have problems such as a limited response range, a large dark current, and a low detectivity. The performance of its optoelectronic detectors can be further improved by constructing a van der Waals heterojunction. The built-in electric field of the heterojunction can form a high-energy potential barrier at the interface, effectively blocking the transport of dark-state carriers, thereby reducing the dark current of the device. At the same time, based on the layered ultrathin structural characteristics of two-dimensional materials and the advantage of no dangling bonds on the surface, various van der Waals heterostructures can be formed by combining and stacking different two-dimensional materials, or two-dimensional materials can be compounded with zero-dimensional, one-dimensional, or three-dimensional materials to form mixed-dimensional heterostructures. These heterostructures combined by van der Waals interactions provide a convenient means for the performance regulation and optimization of two-dimensional materials, and are of great significance for the development and research of new two-dimensional material devices. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of high dark current, low on-off ratio, and low specific detectivity of Bi 2 O 2 Se-based optoelectronic detectors, and to provide a bismuth telluride / bismuth oxy selenide heterojunction optoelectronic detector and a preparation method thereof.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A bismuth telluride / bismuth oxy selenide heterojunction optoelectronic detector, wherein the optoelectronic detector includes a Bi 2 O 2 Se layer, Bi2 Te 3 layer and two gold electrodes, the Bi 2 O 2 Se layer and the Bi 2 Te 3 layers are vertically stacked by two-dimensional material transfer technology to form a Bi 2 Te 3 / Bi 2 O 2 Se heterostructure.

[0007] Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector has a dark current on the order of 10 -13 A at the 0-bias state. The Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector has a switching ratio greater than 10 3 and a specific detectivity greater than 10 11 Jones.

[0008] Furthermore, the thickness of the Bi 2 O 2 Se layer is 5 - 10 nm.

[0009] Furthermore, the thickness of the gold electrodes is 50 - 100 nm.

[0010] Furthermore, the Bi 2 O 2 Se layer and the Bi 2 Te 3 layers are grown on a mica substrate by chemical vapor deposition.

[0011] Furthermore, the two gold electrodes are respectively located on the Bi 2 O 2 Se layer and the Bi 2 Te 3 layers.

[0012] A preparation method of the above bismuth telluride / bismuth oxy selenide heterojunction photodetector, the method comprising the following steps:

[0013] Step 1, grow a Bi 2 O 2 Se layer on a mica substrate by chemical vapor deposition;

[0014] Step 2, transfer the Bi 2 Te 3 layer to the Bi2 O 2 Above the Se layer, form Bi 2 Te 3 / Bi 2 O 2 Se heterostructure;

[0015] Step 3: Use electron beam evaporation method to deposit gold electrodes on the Bi 2 Te 3 layer and the Bi 2 O 2 Se layer respectively, and obtain a Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector.

[0016] Furthermore, in Step 1, the chemical vapor deposition method is specifically:

[0017] (1) Use Bi 2 Se 3 and Bi 2 O 3 powders as growth sources, 100 - 120 sccm argon as the growth carrier gas, and a single - temperature - zone tube furnace as the growth equipment. Place the Bi 2 O 3 powder in the central temperature zone and heat it to 585 - 595 °C;

[0018] (2) Place the Bi 2 Se 3 powder 18 - 20 cm upstream from the central temperature zone in the quartz tube, and place the mica substrate 18 - 20 cm downstream from the center in the quartz tube;

[0019] (3) Control the growth time to be 30 - 60 min.

[0020] Furthermore, in Step 2, use PDMS to directly pick up the Bi 2 Te 3 layer from the PMMA during transfer.

[0021] Furthermore, in Step 3, the beam current for depositing the gold electrode is 90 - 120 mA.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention uses two two - dimensional materials to build a Bi 2 Te 3 / Bi 2 O 2 Se heterojunction, forming a van der Waals contact at the interface, which is beneficial to the interfacial transport of carriers and improves the photoelectric response of the detector.

[0024] 2. The present invention constructs a Bi 2 Te 3 / Bi 2 O 2 Se heterojunction to form an interfacial potential barrier, suppressing the dark current of the device. The Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector has a dark current of only on the order of 10 -13 A at zero bias.

[0025] 3. The Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector of the present invention has a switching ratio greater than 10 3 at a bias of 1V. Compared with the Bi 2 O 2 Se-based photodetector, it is increased by about 100 times, and the specific detectivity is higher than 10 11 Jones. Compared with the Bi 2 O 2 Se-based photodetector, it is increased by one order of magnitude.

[0026] 4. The Bi 2 Te 3 / Bi 2 O 2 Se heterojunction of the present invention is prepared by an improved two-dimensional material transfer method. Bi 2 Te 3 is directly picked up from PMMA using viscoelastic PDMS, and then subsequent steps are carried out, avoiding the problem of incomplete degumming and interfacial contamination caused by the degumming process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic structural diagram of the Bi 2 Te 3 / Bi 2 O 2 Se heterojunction of the present invention;

[0028] Figure 2 FIG. is a schematic process flow diagram of the transfer of the Bi 2 Te 3 / Bi 2 O 2 Se heterojunction prepared in Example 1;

[0029] Figure 3 FIG. is the Bi 2 Te 3 / Bi 2 O 2 Optical microscope image of the Bi 2 O 2 / Bi 2 O 2 Se heterojunction photodetector;

[0030] Figure 4 The Bi 2 Te 2 / Bi 2 O 2 Se heterojunction prepared in Example 1; 2 Te 3 / Bi 2 O 2 Raman spectrum of the Bi 2 Te 3 / Bi 2 O 3 Se heterojunction;

[0031] Figure 5 The Bi 2 Te 3 / Bi 2 O 3 Se heterojunction photodetector prepared in Example 1; 2 Te 3 / Bi 2 O 2 I-V curve of the Bi 2 Te 3 / Bi 2 O 3 Se heterojunction photodetector;

[0032] Figure 6 The Bi 2 Te 3 / Bi 2 O 3 Se heterojunction photodetector prepared in Example 1; 2 Te 3 / Bi 2 O 2 I-t curve of the Bi 2 Te 2 / Bi 2 O 2 Se heterojunction photodetector;

[0033] Figure 7 The Bi 2 O 2 Se-based photodetector prepared in Comparative Example 1; the dark state I-V curve of the Bi 2 O 2 Se-based photodetector and the dark state I-V curve of the Bi 2 Te 3 / Bi 2 O 3 Se heterojunction photodetector prepared in Example 1; 2 O 2 Se-based photodetector dark state I-V curve and the Bi 2 Te 3 / Bi 2 O 3 Se heterojunction photodetector prepared in Example 1; 2 Te 3 / Bi 2 O 2 Comparison chart of the dark state I-V curves; Figure 8 The Bi 2 O 2 Se-based photodetector prepared in Comparative Example 1; 2 O 2 I-t curve of the Bi 2 O 2 Se-based photodetector. Detailed implementation manners

[0034] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0035] Example 1:

[0036] A Bi 2 Te 3 / Bi 2 O 3 Se heterojunction, comprising a two-dimensional Bi 2 Te 3 layer and a two-dimensional Bi 2 O 2 layer; 2 Te 3 / Bi 2 O 2 Se heterojunction, including a two-dimensional Bi 2 Te 3 layer and a two-dimensional Bi 2 O 2 layer; 2 Te 3 layer and a two-dimensional Bi 2 O 2 layer; 2 O2 The Se layer, both of which are grown on a mica substrate by chemical vapor deposition and stacked to form a van der Waals heterojunction through an improved two-dimensional material transfer technique. The transfer process is as follows: Figure 2 As shown, two electrodes are deposited by electron beam evaporation technology to prepare a Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector.

[0037] The preparation method of the Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector in this embodiment includes the following steps:

[0038] Step 1: Weigh 0.2 g of Bi 2 Se 3 and 0.4 g of Bi 2 O 3 powder as the growth source. Place the Bi 2 O 3 powder in the central temperature zone of the vacuum tube furnace, place the Bi 2 Se 3 powder 20 cm upstream from the center of the quartz tube, and place the mica substrate 18 cm downstream from the center of the quartz tube;

[0039] Step 2: Set the growth temperature program: the central temperature is 585 °C, the heating time is 50 min, and the holding time is 1 h. Pass 200 sccm of argon gas through the quartz tube for 10 min to clean it to avoid the influence of air residue on the growth process. Then adjust the argon gas flow rate to 100 - 120 sccm as the carrier gas, and keep the reaction chamber pressure at 120 Pa to prepare Bi 2 O 2 Se;

[0040] Step 3: Spin-coat PMMA with a mass fraction of 6% on the Bi 2 Te 3 sample. Place the sample spin-coated with PMMA on a heating table and bake it at 80 °C for 5 min to cure the PMMA. Then, due to the different wetting characteristics of PMMA and the mica substrate, use deionized water to assist in peeling off PMMA / Bi 2 Te 3 ;

[0041] Step 4: Pick up Bi 2 Te 3 from PMMA with viscoelastic PDMS. Subsequently, use a two-dimensional material transfer platform to align Bi 2 Te 3 with the target Bi2 O 2 Se sample, and lower the robotic arm to make Bi 2 Te 3 and Bi 2 O 2 Se come into full contact. Then heat the transfer platform to 80 °C and keep it for 15 min, and then lift the robotic arm to obtain Bi 2 Te 3 / Bi 2 O 2 Se heterojunction;

[0042] Step Five: Place the Bi 2 Te 3 / Bi 2 O 2 Se heterojunction into a tube furnace and anneal it at 150 °C for 1 h under an argon atmosphere, aiming to enhance the bonding between the Bi 2 Te 3 layer and the Bi 2 O 2 Se layer;

[0043] Step Six: Adopt the method of electron beam evaporation, keep the pressure in the cavity below 4.5×10 -4 Pa, and evaporate the gold electrode to obtain the Bi 2 Te 3 / Bi 2 O 2 Se heterojunction photodetector.

[0044] The samples prepared above were characterized by optical microscopy and Raman spectroscopy, as shown in detail in Figure 3 and 4 . The prepared Bi 2 O 2 Se / Bi 2 Te 3 heterojunction is stacked by hexagonal Bi 2 Te 3 and square Bi 2 O 2 Se, the geometric shapes of both are complete, and there are no obvious contaminants on the surface. It can be clearly observed from Figure 4 the Raman vibration peaks corresponding to Bi 2 Te 3 and Bi 2 O 2 Se. The full width at half maximum is small and the characteristic peaks are obvious, indicating that Bi 2 Te 3 and Bi 2 O 2 Se have good crystallinity and high purity. For the prepared Bi 2 O 2Se / Bi 2 Te 3 The optoelectronic performance of the heterojunction device was tested. A voltage was applied to the Bi 2 O 2 Se end, and the Bi 2 Te 3 end was grounded. The Bi 2 O 2 Se / Bi 2 Te 3 I-V characterization of the heterojunction is as shown in Figure 5 Bi 2 O 2 Se / Bi 2 Te 3 The I-V curve of the Bi -13 Se / Bi Figure 6 2 O 2 Se / Bi 2 3 Teheterojunction shows obvious rectifying characteristics, with a rectification ratio of about 20 (|V| = 4V) and an ultra-low dark current of 10 2 at 0V bias. As the incident light power increases, the photocurrent of the device also increases. Figure 6 11 Figure

[0045] To confirm the improvement of the Bi 2 Te 3 / Bi 2 O 2 Se heterojunction on the optoelectronic detection performance such as dark current, on-off ratio and specific detectivity of the photodetector, a Bi 2 O 2 Se-based photodetector was prepared for comparison. See Comparative Example 1 for details.

[0046] Comparative Example 1:

[0047] Bi 2 O 2 The Se-based photodetector includes a Bi 2 O 2 Se layer grown on a mica substrate and gold electrodes at both ends. The preparation process includes the following steps:

[0048] Step 1: Weigh 0.2 g of Bi2 Se 3 and 0.4 g of Bi 2 O 3 powder as the growth source, place the Bi 2 O 3 powder in the central temperature zone of a vacuum tube furnace, place the Bi 2 Se 3 powder 20 cm upstream from the center of the quartz tube, and place the mica substrate 18 cm downstream from the center of the quartz tube;

[0049] Step 2. Set the growth temperature program: the central temperature is 585 °C, the heating time is 50 min, and the holding time is 1 h; introduce 200 sccm of argon to clean the quartz tube for 10 min, adjust the argon flow rate to 100 sccm, and maintain the reaction chamber pressure at 120 Pa to prepare Bi 2 O 2 Se;

[0050] Step 3. Use the electron beam evaporation method to evaporate the gold electrode while keeping the chamber pressure below 4.5×10 -4 Pa to obtain a Bi 2 O 2 Se-based photodetector.

[0051] Perform I-V and I-t tests on the prepared Bi 2 O 2 Se-based photodetector, see details in Figure 7 and 8 . Compare the dark I-V curves of the above two photodetectors. As Figure 7 shown, under forward bias, the dark current of the Bi 2 O 2 Se / Bi 2 Te 3 heterojunction is significantly lower than that of the Bi 2 O 2 Se nanosheets. At a bias voltage of 1.5 V, the dark current of the Bi 2 O 2 Se / Bi 2 Te 3 heterojunction photodetector is 0.28 nA, while the dark current of the Bi 2 O 2 Se-based photodetector is 2.51 nA, indicating that the heterojunction effectively reduces the dark current by one order of magnitude. From the I-t test results of the Bi 2 O 2 Se-based device, its responsivity can be calculated to be 0.14 A / W, the specific detectivity is 1.21×10 10 Jones, and the on-off ratio is 22. Comparing the photodetection performance of the two devices, it can be found that: compared with Bi2 O 2 Se-based photodetector, Bi 2 Te 3 / Bi 2 O 2 The performance of the Se / Bi 2 O heterojunction photodetector has been comprehensively improved.

[0052] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A bismuth telluride / bismuth oxygen selenide heterojunction photodetector, characterized in that: The photodetector includes a Bi2O2Se layer, a Bi2Te3 layer and two gold electrodes. The Bi2O2Se layer and the Bi2Te3 layer are vertically stacked by a two-dimensional material transfer technology to form a Bi2Te3 / Bi2O2Se heterostructure.

2. The bismuth telluride / bismuth oxygen selenide heterojunction photodetector according to claim 1, characterized in that: The Bi2O2Se layer has a thickness of 5 to 10 nm.

3. The bismuth telluride / bismuth oxygen selenide heterojunction photodetector according to claim 1, characterized in that: The thickness of the gold electrode is 50 to 100 nm.

4. The bismuth telluride / bismuth oxygen selenide heterojunction photodetector according to claim 1, characterized in that: The Bi2O2Se layer and the Bi2Te3 layer are grown on a mica substrate by chemical vapor deposition.

5. The bismuth telluride / bismuth oxygen selenide heterojunction photodetector according to claim 1, characterized in that: Two gold electrodes are located on the Bi2O2Se layer and the Bi2Te3 layer respectively.

6. A method for preparing the bismuth telluride / bismuth oxygen selenium heterojunction photodetector according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: Step 1: growing a Bi2O2Se layer on a substrate by chemical vapor deposition; Step 2: Transfer the Bi2Te3 layer to the top of the Bi2O2Se layer through a two-dimensional material transfer process to form a Bi2Te3 / Bi2O2Se heterostructure; Step 3: Use electron beam evaporation method to evaporate gold electrodes on the Bi2Te3 layer and the Bi2O2Se layer respectively to obtain a Bi2Te3 / Bi2O2Se heterojunction photodetector.

7. The method for preparing the bismuth telluride / bismuth oxygen selenium heterojunction photodetector according to claim 6, characterized in that: In step 1, the chemical vapor deposition method is specifically: (1) Using Bi2Se3 and Bi2O3 powders as growth sources, 100-120 sccm argon as growth carrier gas, and a single-temperature zone tubular furnace as the growth equipment, the Bi2O3 powder is placed in the central temperature zone and heated to 585-595°C; (2) The Bi2Se3 powder is placed 18 to 20 cm upstream of the quartz tube from the central temperature zone, and the mica substrate is placed 18 to 20 cm downstream of the quartz tube from the center; (3) Control the growth time to 30 to 60 minutes.

8. The method for preparing the bismuth telluride / bismuth oxygen selenium heterojunction photodetector according to claim 6, characterized in that: In step 2, PDMS is used to directly pick up the Bi2Te3 layer from PMMA during transfer.

9. The method for preparing the bismuth telluride / bismuth oxygen selenium heterojunction photodetector according to claim 6, characterized in that: In step 3, the beam current for depositing the gold electrode is 90-120 mA.

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