Van der Waals high-brightness on-chip integratable light emitting diode and preparation method thereof

Abstract

The invention discloses a Van der Waals high-brightness on-chip integratable light emitting diode and a preparation method thereof. The Van der Waals high-brightness on-chip integratable light emitting diode comprises a substrate, parallel opposite end electrodes, a charge transport material and an active material, the parallel opposite-end electrode is arranged above the substrate, the active material is positioned above one end of the parallel opposite-end electrode and forms electrical contact with one end of the parallel opposite-end electrode, and the active material and the parallel opposite-end electrode form a vertical overlapping area serving as a drain electrode; one end of the charge transmission material covers the vertical overlapping region, and the other end of the charge transmission material is in electrical contact with the other end of the parallel opposite-end electrode to serve as a source electrode; under the driving of forward bias voltage, electrons and holes are injected into the active material from the source electrode and the drain electrode respectively, and due to the high quantum yield of the active material under high carrier concentration and the collaborative optimization of carrier injection and blocking on the device structure, the device can realize extremely high peak brightness under high current density.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices, and specifically relates to a van der Waals high-brightness on-chip integrated light-emitting diode based on a quasi-infinite layer of Gamma-phase indium selenide and a preparation method thereof. Background Art

[0002] On-chip integrated light sources are one of the key active devices in building photonic integrated circuits, primarily responsible for achieving high-efficiency electro-optical conversion. Currently, three types of material systems face different challenges:

[0003] (1) Traditional light sources based on III-V semiconductor materials are limited by the high growth temperature and lattice matching required, and are difficult to be compatible with silicon-based CMOS processes.

[0004] (2) Although emerging perovskite materials can be prepared by solution spin coating and are therefore compatible with silicon-based processes, they are limited by low mobility, low thermal stability, low air stability, and performance loss after miniaturization. It is still challenging to achieve high-performance and highly reliable on-chip light sources based on perovskite materials.

[0005] (3) Van der Waals materials have become a potential system for constructing on-chip optoelectronic devices due to their unique advantages in on-chip integration and high adjustability. However, the peak brightness of current van der Waals light-emitting diodes does not meet the requirements of on-chip optical communications, sensing, computing and other applications. This is mainly due to the severe efficiency roll-off induced by exciton-exciton annihilation of active layer materials such as atomically thin transition metal chalcogenides and black phosphorus at high injection rates. Summary of the Invention

[0006] Purpose of the invention: In order to solve the problem of low peak brightness of current van der Waals light-emitting diodes, the present invention proposes a van der Waals high-brightness on-chip integrated light-emitting diode based on quasi-infinite layer gamma phase indium selenide and its preparation method.

[0007] Technical solution: In the first aspect, the present invention proposes a van der Waals high-brightness on-chip integrated light-emitting diode, comprising: a substrate, parallel opposite-end electrodes, a charge transport material, and an active material;

[0008] The parallel opposing electrodes are placed above the substrate, and the active material is located above one end of the parallel opposing electrodes and forms an electrical contact with the one end of the parallel opposing electrodes, and the two form a vertical overlapping region, which serves as a drain;

[0009] One end of the charge transport material covers the vertical overlap region, and the other end of the charge transport material forms an electrical contact with the other end of the parallel opposite electrode, serving as a source electrode;

[0010] Driven by a forward bias voltage, electrons and holes are injected into the active material from the source and drain, respectively, to achieve near-infrared luminescence with peak brightness.

[0011] Furthermore, the substrate is a semiconductor material having an oxide layer on the surface.

[0012] Furthermore, the distance between the parallel opposite electrodes is 20 μm to 40 μm, and the bias voltage applied to the parallel opposite electrodes is in the range of 1V to 5V.

[0013] Furthermore, the charge transport material is a thin layer of graphene with a thickness between 5 nm and 15 nm.

[0014] Furthermore, the active material is a quasi-infinite layer of Gamma-phase indium selenide, and its thickness is between 20 nm and 1000 nm.

[0015] In a second aspect, the present invention provides a method for preparing a van der Waals high-brightness on-chip integrated light-emitting diode, comprising the following steps:

[0016] Step 1: Cleaning the substrate to obtain a cleaned substrate;

[0017] Step 2: Spin-coating photoresist on the cleaned substrate, and sequentially patterning the photoresist and thermal evaporation to prepare parallel opposite-end electrodes on the cleaned substrate;

[0018] Step 3: Select quasi-infinite layer Gamma phase indium selenide and thin layer graphene;

[0019] Step 4: Using a dry transfer process using polydimethylsiloxane as a medium, the quasi-infinite layer of gamma-phase indium selenide and the thin-layer graphene are sequentially micro-transferred to the target location, such that the quasi-infinite layer of gamma-phase indium selenide is located above and electrically contacts one end of the parallel opposing electrode, forming a vertically overlapping region, and one end of the thin-layer graphene covers the vertically overlapping region, with the other end of the thin-layer graphene forming an electrical contact with the other end of the parallel opposing electrode;

[0020] Step 5: Anneal the device prepared in step 4 in an N2 atmosphere to obtain a van der Waals high-brightness on-chip integrated light-emitting diode.

[0021] Furthermore, the substrate is a semiconductor material having an oxide layer on the surface.

[0022] Furthermore, the distance between the parallel opposite electrodes is 20 μm to 40 μm, and the bias voltage applied to the parallel opposite electrodes is in the range of 1V to 5V.

[0023] Furthermore, the parallel opposite-end electrodes include: 5 nm titanium and 50 nm gold.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention discloses a high-performance on-chip light-emitting diode based on layered van der Waals materials, comprising: gamma-phase indium selenide, few-layer graphene, and two unconnected gold electrodes; wherein the indium selenide serves as an active layer (light-emitting layer), and the few-layer graphene and the gold electrodes serve as source and drain contacts; under forward bias voltage drive, electrons and holes are injected into the active layer by the graphene and the gold, respectively. Thanks to the high quantum yield under high carrier concentration in the active layer and the coordinated optimization of carrier injection and blocking in the device structure, the device can achieve extremely high peak brightness at high current density;

[0026] (2) The high-brightness on-chip integrated light-emitting diode based on quasi-infinite layer gamma-phase indium selenide proposed in the present invention has the characteristics of high brightness, high efficiency, high stability, low cost, easy preparation and easy on-chip integration, providing a new solution for micro-scale light-emitting diodes and having practical application potential in large-area arrays;

[0027] (3) The high-brightness on-chip integrated light-emitting diode based on quasi-infinite layer gamma-phase indium selenide proposed in the present invention can be applied to on-chip communication, computing, sensing and other application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of a van der Waals high-brightness on-chip integrated light-emitting diode based on thin-layer graphene-quasi-infinite layer Gamma-phase indium selenide-titanium / gold proposed by the present invention;

[0029] Figure 2 The thickness-dependent photoluminescence quantum yield of Gamma-phase InSe thin film varies with the generation rate;

[0030] Figure 3 The electroluminescence spectrum of the van der Waals high-brightness on-chip integrated light-emitting diode of the present invention is dependent on the driving current;

[0031] Figure 4 Bright field optical microscopic images and electroluminescent images of the van der Waals high-brightness on-chip integrable light-emitting diode of the present invention in the turned-off and turned-on states;

[0032] Figure 5 Graph showing the variation of the external quantum yield (red line) and radiance (blue line) of the van der Waals high-brightness on-chip integrated light-emitting diode of the present invention with the injected current density;

[0033] Figure 6Images showing the brightness and voltage stability of a high-brightness van der Waals on-chip integrated light-emitting diode based on thin-layer graphene-quasi-infinite layer gamma-phase indium selenide-titanium / gold.

[0034] Figure 7 The figure is a comparison chart of the changes in radiance of reported near-infrared perovskite light-emitting diodes, organic light-emitting diodes, quantum dot light-emitting diodes, van der Waals light-emitting diodes and the van der Waals high-brightness on-chip integrated light-emitting diode of the present invention as a function of injection current density. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will now be further described with reference to the accompanying drawings and embodiments.

[0036] Example 1:

[0037] like Figure 1 As shown, this embodiment discloses a high-brightness on-chip integrated light-emitting diode based on a quasi-infinite layer of gamma-phase indium selenide, which mainly includes: a substrate 1, parallel opposite-end electrodes 2, a charge transport material 3, and an active material 4; the parallel opposite-end electrodes 2 are placed above the substrate 1, the active material 4 is above one end of the parallel opposite-end electrodes 2 and forms a good electrical contact, one end of the charge transport material 3 covers the vertical overlapping area formed by the active material 4 and the parallel opposite-end electrodes 2, and the other end forms a good electrical contact with the parallel opposite-end electrodes 2 not covered with the active material 4. Figure 1 Reference numeral 5 in FIG. 5 denotes an electroluminescent light beam to be measured.

[0038] In this embodiment, the substrate 1 is a semiconductor material such as silicon with a 300nm oxide layer on the surface, and the oxide layer serves as an insulating layer. The parallel opposing electrodes 2 are made of a material with good conductivity such as gold and titanium, and the distance between the two unconnected parallel opposing electrodes is 20μm to 40μm. The bias voltage applied to the parallel opposing electrodes 2 ranges from 1V to 5V. The charge transfer material 3 is a thin layer of graphene or a few-layer graphene with a thickness between 5nm and 15nm; the active material 4 is a high-brightness and high-efficiency material. In this embodiment, a quasi-infinite layer of gamma-phase indium selenide is used, and its thickness is between 20nm and 1000nm. The active material 4 serves as the active layer (light-emitting layer).

[0039] The working principle of this embodiment is as follows: for the parallel opposite electrodes 2, the end in contact with the active material 4 is the drain, and the end in contact with the charge transport material 3 is the source. Under the forward bias voltage, electrons and holes are injected into the active material 4 from the source and drain respectively. Figure 2The active material 4 shown exhibits high quantum yields at high carrier concentrations at various thicknesses, and the device structure exhibits coordinated optimization of carrier injection and blocking, enabling the device to achieve extremely high peak brightness at high current densities. Therefore, the light-emitting diode proposed in this embodiment has the characteristics of high brightness, high efficiency, high stability, and ease of fabrication, making it suitable for the fabrication of high-brightness micro-sized light-emitting arrays.

[0040] Example 2:

[0041] This embodiment discloses a high-brightness, on-chip, integratable light-emitting diode based on quasi-infinite layers of gamma-phase indium selenide. The diode comprises a silicon substrate, a charge transport material composed of thin-layer graphene, an active material composed of quasi-infinite layers of gamma-phase indium selenide, and parallel opposing electrodes. The quantum yield of the quasi-infinite layers of gamma-phase indium selenide used is as high as 32.7%. Both the quasi-infinite layers of gamma-phase indium selenide and the thin-layer graphene used in this embodiment are prepared by mechanical exfoliation. The parallel opposing electrodes are spaced 35 μm apart.

[0042] The steps for preparing a high-brightness on-chip integrable light-emitting diode based on a quasi-infinite layer of gamma-phase indium selenide proposed in this embodiment include:

[0043] Step 1: A silicon wafer with a 300nm oxide layer on its surface was rinsed with acetone and isopropyl alcohol for 1 minute using a wash bottle. Organic matter remaining on the surface of the silicon wafer was removed by spraying with an air gun connected to a nitrogen cylinder. The silicon wafer was further cleaned with oxygen plasma at a power of 50W, a flow rate of 50sccm, and a duration of 5 minutes.

[0044] Step 2: Parallel electrodes are 5 nm of titanium and 50 nm of gold, which are made by conventional laser direct write lithography and thermal evaporation. That is, photoresist is spin-coated on the substrate, the photoresist is patterned by ultraviolet exposure, development, and fixing, and a pair of electrodes (3) are formed on the substrate by thermal evaporation. After preparation, the substrate is further cleaned according to the parameters of step 1.

[0045] Step 3: Use fluorescence microscopy and optical microscopy to select suitable quasi-infinite layer gamma-phase indium selenide and thin-layer graphene samples on PDMS for use in step 4; specifically, use blue tape to peel off the quasi-infinite layer gamma-phase indium selenide from the indium selenide block.

[0046] Step 4: Using polydimethylsiloxane (PDMS) as a medium for dry transfer process, the quasi-infinite layer of Gamma phase indium selenide and thin layer of graphene are sequentially micro-transferred to the target position to form Figure 1 stacking method; heated to 70°C during the micro-transfer process.

[0047] Step 5: Anneal the fabricated device at 120° C. in a N 2 atmosphere for 30 minutes to ensure good contact between interfaces.

[0048] Figure 3 The electroluminescence spectra of a high-brightness on-chip integrated light-emitting diode based on a quasi-infinite layer of gamma-phase indium selenide were shown at different drive currents. The device turned on at voltages above 1.1V, and the brightness increased dramatically with increasing drive current. Figure 4 Bright-field optical microscopy images and electroluminescence images of the device at different driving voltages are shown. As the driving voltage increases, the vertical overlapping area of the few-layer graphene / quasi-infinite layer gamma-phase indium selenide / opposite electrode shows more uniform high-brightness surface luminescence.

[0049] Figure 5 The graph shows the variation of the external quantum yield (red line) and radiance (blue line) of the van der Waals high-brightness on-chip integrated light-emitting diode electroluminescence as a function of the injection current density. The device's external quantum yield can reach up to 6.4% and there is no significant efficiency roll-off under the premise of high injection current density. At the same time, the device can achieve a maximum power of 19500W sr -1 m -2 High radiance injection and high brightness emission. Figure 6 The device was demonstrated to have an initial irradiance of 297W sr -1 m -2 and a constant injection current density of 1.45×10 5 mAcm -2 According to the stability test results under 3D scanning, the device can operate stably for more than 50 hours without significant changes in driving voltage and radiance.

[0050] Figure 7 A comparison of the radiance of reported near-infrared perovskite light-emitting diodes, organic light-emitting diodes, quantum dot light-emitting diodes, van der Waals light-emitting diodes, and high-brightness van der Waals on-chip integrated light-emitting diodes as a function of injection current density is presented. This device achieves the highest external quantum yield at high injection current density and exhibits no significant efficiency roll-off at even higher injection densities.

Claims

1. A van der Waals high-brightness on-chip integrated light-emitting diode, characterized in that: include: substrate, parallel opposing electrodes, charge transport material, and active material; The parallel opposing electrodes are placed above the substrate, and the active material is located above one end of the parallel opposing electrodes and forms an electrical contact with the one end of the parallel opposing electrodes, and the two form a vertical overlapping region, which serves as a drain; One end of the charge transport material covers the vertical overlap region, and the other end of the charge transport material forms an electrical contact with the other end of the parallel opposite electrode, serving as a source electrode; Driven by a forward bias voltage, electrons and holes are injected into the active material from the source and drain, respectively, to achieve near-infrared luminescence with high peak brightness.

2. The van der Waals high-brightness on-chip integrable light-emitting diode according to claim 1, characterized in that: The substrate is a semiconductor material with an oxide layer on the surface.

3. The van der Waals high-brightness on-chip integrable light-emitting diode according to claim 1, characterized in that: The distance between the parallel opposite-end electrodes is 20 μm to 40 μm, and the bias voltage applied to the parallel opposite-end electrodes is in the range of 1V to 5V.

4. The van der Waals high-brightness on-chip integrable light-emitting diode according to claim 1, characterized in that: The charge transport material is a thin layer of graphene with a thickness ranging from 5 nm to 15 nm.

5. The van der Waals high-brightness on-chip integrable light-emitting diode according to claim 1, characterized in that: The active material is a quasi-infinite layer of Gamma phase indium selenide, and the thickness thereof is between 20 nm and 1000 nm.

6. A method for preparing a high-brightness van der Waals on-chip integrated light-emitting diode, characterized by: The following steps are involved: Step 1: Cleaning the substrate to obtain a cleaned substrate; Step 2: Spin-coating photoresist on the cleaned substrate, and sequentially patterning the photoresist and thermal evaporation to prepare parallel opposite-end electrodes on the cleaned substrate; Step 3: Select quasi-infinite layer Gamma phase indium selenide and thin layer graphene; Step 4: Using a dry transfer process using polydimethylsiloxane as a medium, the quasi-infinite layer of gamma-phase indium selenide and the thin-layer graphene are sequentially micro-transferred to the target location, such that the quasi-infinite layer of gamma-phase indium selenide is located above and electrically contacts one end of the parallel opposing electrode, forming a vertically overlapping region, and one end of the thin-layer graphene covers the vertically overlapping region, with the other end of the thin-layer graphene forming an electrical contact with the other end of the parallel opposing electrode; Step 5: Anneal the device prepared in step 4 in an N2 atmosphere to obtain a van der Waals high-brightness on-chip integrated light-emitting diode.

7. The method for preparing a high-brightness van der Waals on-chip integrated light-emitting diode according to claim 6, characterized in that: The substrate is a semiconductor material with an oxide layer on the surface.

8. The method for preparing a high-brightness van der Waals on-chip integrated light-emitting diode according to claim 6, characterized in that: The distance between the parallel opposite-end electrodes is 20 μm to 40 μm, and the bias voltage applied to the parallel opposite-end electrodes is in the range of 1V to 5V.

9. The method for preparing a high-brightness van der Waals on-chip integrated light-emitting diode according to claim 6, characterized in that: The parallel opposite-end electrodes include 5 nm of titanium and 50 nm of gold.

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