Monolithic integrated micron-sized light emitting diode chip and application thereof

Abstract

The invention provides a monolithic integrated micron-sized LED chip, which comprises a substrate and a plurality of micron-sized LED devices, each micron-sized LED device comprises an n-gallium nitride layer, an indium gallium nitride / gallium nitride multi-quantum well structure, a p-aluminum gallium nitride layer, a p-gallium nitride layer, a current diffusion layer and a passivation layer, the thickness of a quantum barrier is 0.5-5nm, and the thickness of the current diffusion layer is 0.5-5nm. The monolithic integrated micron-sized LED chip can be used for optical detection through the high-voltage bias circuit, the high-voltage bias circuit provides a reverse bias voltage of 0-200V, and the bandwidth of the high-voltage bias circuit is 10MHz-10GHz; the monolithic integrated micron-sized LED chip can be used for light emission, and the bandwidth of the monolithic integrated micron-sized LED chip is 10 MHz to 10 GHz. The monolithic integrated micron-sized LED chip disclosed by the invention has better photoelectric response characteristic and bandwidth characteristic under extremely high reverse bias voltage. The invention further provides application of the monolithic integrated micron-sized LED chip as a narrow-band photoelectric detector and application of the monolithic integrated micron-sized LED chip in high-speed visible light communication, and further provides a visible light communication device.

Description

Technical Field

[0001] The present invention relates to the field of photonic chip technology, and in particular to a monolithic integrated micron-level light emitting diode (Micro-LED) chip, the application of the monolithic integrated Micro-LED chip as a narrow-band photodetector, a visible light communication device, and the application of the monolithic integrated Micro-LED chip in high-speed visible light communication. Background Art

[0002] With the exponential growth of IoT devices and applications, traditional radio frequency (RF) communications are facing the problem of increasingly tight spectrum resources and will not be able to meet large-scale access and people's needs for high-speed wireless data rates. Visible light communication technology is a new type of wireless optical communication technology that can combine lighting and communication and has extremely broad application prospects and development space. Compared with traditional radio frequency, visible light communication has the advantages of unrestricted spectrum, high transmission rate, large communication capacity, safety and energy saving, and is an effective supplement to radio frequency technology. Visible light communication systems mainly use LED (Light Emitting Diode) as signal transmitters, but the bandwidth of commercial LEDs is only tens of MHz, which greatly limits the rate of visible light communication. In order to overcome this problem, researchers have proposed micron-level light-emitting diodes (Micro-LEDs), which have the advantages of high current density, high brightness, and small junction capacitance. Its modulation bandwidth can reach hundreds of MHz, greatly improving the communication rate. In addition, the receiving end of the current visible light communication system mostly uses commercial silicon-based photodetectors, but the spectral response range of silicon-based photodetectors is wide, which will introduce optical noise. Micro-LED can not only be used as a light emitting device in visible light communication systems, but also can be used as a photodetector to achieve photoelectric conversion without changing the structure and materials of quantum wells (MQWs). Micro-LED chip photodetectors have the advantages of wavelength selectivity, low dark current and high responsiveness. At the same time, Micro-LED also has the characteristics of self-power supply, and can still generate photocurrent without external power supply.

[0003] However, the prior art uses Micro-LED chips with single performance for visible light communication devices, which have high power consumption and cost, and low modulation bandwidth, which can only reach tens to hundreds of MHz, limiting the data rate of visible light communication devices. In addition, the prior art uses commercial silicon-based photodetectors as receivers of visible light communication systems, which will generate high optical noise, thereby limiting the data rate of visible light communication devices. Moreover, there are no reports in the prior art on the multifunctional application of single Micro-LED chips in visible light communication.

[0004] Therefore, it is of great significance to provide a monolithic integrated Micro-LED chip, a visible light communication device using a monolithic integrated Micro-LED chip, and the application of the monolithic integrated Micro-LED chip in high-speed visible light communication, as well as the application of the monolithic integrated Micro-LED chip as a narrow-band photodetector, in order to solve or at least alleviate at least one of the above-mentioned technical problems. Summary of the invention

[0005] In view of the above-mentioned technical problems, the present invention provides a monolithic integrated micron-sized light emitting diode (Micro-LED) chip, a visible light communication device, the application of a monolithic integrated Micro-LED chip as a narrow-band photodetector, and the application of a monolithic integrated Micro-LED chip in high-speed visible light communication, so as to solve or at least alleviate at least one technical problem existing in the above-mentioned Micro-LED chip and visible light communication device.

[0006] In a first aspect, the present invention provides a monolithic integrated micron-sized light-emitting diode chip, comprising: a substrate and a plurality of micron-sized light-emitting diode devices distributed in an array on the substrate, each micron-sized light-emitting diode device comprising an n-GaN layer, an InGaN / GaN multi-quantum well structure, a p-AlGaN layer, a p-GaN layer and a current diffusion layer stacked in sequence, and a passivation layer located on the sides of the InGaN / GaN multi-quantum well structure, the p-AlGaN layer, the p-GaN layer and the current diffusion layer, the quantum barrier thickness in the InGaN / GaN multi-quantum well structure is 0.5-5nm, the monolithic integrated micron-sized light-emitting diode chip can be used for light detection through a high-voltage bias circuit, the high-voltage bias circuit can provide a reverse bias voltage of 0V-200V, and the detection bandwidth under different voltages is 10MHz-10GHz; the monolithic integrated micron-sized light-emitting diode chip can also be used for light emission, and the bandwidth when used for light emission is 10MHz-10GHz.

[0007] Optionally, the number of quantum well pairs in the InGaN / GaN multiple quantum well structure is 1-20.

[0008] Optionally, a first electrode layer is disposed on the surface of the current diffusion layer to form a p-contact layer; a second electrode layer is disposed on the surface of the n-GaN layer to form an n-contact layer, and the second electrode layer is spaced apart from the passivation layer.

[0009] Optionally, the first electrode layer is a Ti—Al—Ti—Au metal layer and / or the second electrode layer is a Ti—Al—Ti—Au metal layer.

[0010] Optionally, the size of each micrometer-sized light-emitting diode device is 1-100 micrometers.

[0011] In a second aspect, the present invention provides an application of a monolithically integrated micron-sized light-emitting diode chip as described above as a narrow-band photodetector, wherein the narrow-band photodetector exhibits wavelength selectivity and a spectral response full width at half maximum of 10-50nm.

[0012] In a third aspect, the present invention provides a visible light communication device, wherein a transmitting end, a relay end, or a receiving end of the visible light communication device adopts any one of the monolithically integrated micron-level light emitting diode chips as described above.

[0013] Optionally, a single micron-sized light emitting diode device is used as a transmitting end of the visible light communication apparatus, and a -3dB modulation bandwidth of the single micron-sized light emitting diode device is 10MHz to 10GHz.

[0014] Optionally, a single micron-sized light emitting diode device is used as a transmitting end of a visible light communication device, and the communication rate of the visible light communication device reaches 1-100 Gbps.

[0015] Optionally, a single micron-sized light emitting diode device is used as the receiving end of the visible light communication apparatus, and a -3dB modulation bandwidth of the single micron-sized light emitting diode device is 10MHz to 10GHz.

[0016] Optionally, a single micron-sized light emitting diode device is used as a receiving end of a visible light communication device, and the communication rate of the visible light communication device reaches 1-100 Gbps.

[0017] In a fourth aspect, the present invention provides an application of any monolithically integrated micron-sized light emitting diode chip as described above in high-speed visible light communication, wherein the bandwidth of the monolithically integrated micron-sized light emitting diode chip is greater than or equal to 100 MHz, and the communication rate of the high-speed visible light communication is greater than or equal to 10 Gbps.

[0018] Beneficial effects of the present invention: Different from the prior art, the monolithic integrated micron-scale light-emitting diode chip provided by the present invention can carry out functions such as light signal transmission, reception, modulation and processing, and also has a thinner quantum barrier thickness and a smaller number of quantum well pairs, which can reduce the transit time of photogenerated carriers, and thus can exhibit excellent photoelectric response characteristics and bandwidth under extremely high reverse bias. The monolithic integrated micron-scale light-emitting diode chip of the present invention provides a reverse high bias through a high-voltage bias circuit, which not only makes the absorption area of ​​the device almost exhausted, reduces the carrier diffusion time, but also increases the drift velocity of the carriers, reduces the transit time, and further increases the bandwidth. When the monolithic integrated micron-scale light-emitting diode chip of the present invention is used as a narrow-band photodetector, it exhibits wavelength selectivity at 368 to 416 nm, can achieve narrow-band spectral response, and the spectral response full width at half maximum (FWHM) is only 48 nm. Micro-LED narrow-band photodetectors can be widely used in fields such as color imaging and target recognition. Moreover, the monolithic integrated micron-scale light-emitting diode chip of the present invention can not only serve as the transmitting end and receiving end in the visible light communication system to achieve Gbps high-speed communication, but also serve as the relay end in the visible light communication system to expand the visible light communication range, reduce the probability of link interruption, and improve the reliability and security of the visible light communication system. In addition, it also effectively reduces the size and overall power consumption of the photon integrated system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. 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 the drawings without creative work.

[0020] Figure 1 This is a schematic diagram of the structure of a monolithically integrated Micro-LED chip according to an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the structure of a Micro-LED device according to an embodiment of the present invention;

[0022] Figure 3 The bandwidth characteristics of the monolithically integrated Micro-LED chip of an embodiment of the present invention when used as a photodetector;

[0023] Figure 4 This is a current and voltage characteristic diagram of a monolithically integrated Micro-LED chip according to an embodiment of the present invention when used as a photodetector;

[0024] Figure 5A structural diagram of a visible light communication device when the monolithically integrated Micro-LED chip according to an embodiment of the present invention is used as a transmitting end of the visible light communication device;

[0025] Figure 6 A structural diagram of a visible light communication device when the monolithically integrated Micro-LED chip according to an embodiment of the present invention is used as a receiving end of the visible light communication device;

[0026] Figure 7 for Figure 6 The rate and bit error rate characteristic diagram obtained by performing a visible light communication experiment with a visible light communication device in;

[0027] Figure 8 This is a structural diagram of a visible light communication device when the monolithically integrated Micro-LED chip according to an embodiment of the present invention is used as a relay end of the visible light communication device.

[0028] The reference numerals in the specific implementation manner are as follows:

[0029] Monolithically integrated Micro-LED chip 100;

[0030] Substrate 11, micron-scale light-emitting diode device 12;

[0031] Visible light communication devices 200 , 300 , 400 . DETAILED DESCRIPTION

[0032] The technical solution of the embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0033] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0035] In the description of the present invention, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0036] In the description of the embodiments of the present invention, the orientations or positional relationships indicated by the technical terms "side" and "one side" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present invention and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present invention.

[0037] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0038] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present invention may be combined with other embodiments.

[0039] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0040] See also Figure 1 and 2The first embodiment of the present invention provides a monolithic integrated micron-sized light-emitting diode (Micro-LED) chip 100, which includes a substrate 11 and a plurality of Micro-LED devices 12 distributed in an array on the substrate 11. Each Micro-LED device 12 includes an n-GaN layer, an InGaN / GaN multi-quantum well structure, a p-AlGaN layer, a p-GaN layer, a current diffusion layer, and a passivation layer. The n-GaN layer, the InGaN / GaN multi-quantum well structure, the p-AlGaN layer, the p-GaN layer, and the current diffusion layer are stacked on one side of the substrate 11 in a direction away from the substrate 11, and the passivation layer is arranged on the side of the InGaN / GaN multi-quantum well structure, the p-AlGaN layer, the p-GaN layer, and the current diffusion layer.

[0041] The substrate 11 may be selected from, but not limited to, a sapphire substrate, a silicon substrate, a GaN substrate, a silicon carbide substrate or a flexible PET substrate, or may be selected from other lattice matching substrates. In this embodiment, the substrate 11 is a sapphire substrate.

[0042] The shapes of the multiple Micro-LED devices 12 can be selected according to actual needs, and can be, but not limited to, circular, square, polygonal, etc. In this embodiment, the multiple Micro-LED devices 12 are circular.

[0043] The sizes of multiple Micro-LED devices 12 are selected according to actual needs and can be equal or unequal. Reducing the size of the Micro-LED device 12 can reduce the junction capacitance and resistance of the device, thereby reducing the RC time constant and increasing the bandwidth; but too small a detector size will reduce the light coupling efficiency. Preferably, the size of each Micro-LED device 12 is 1 to 100 μm. More preferably, the size of each Micro-LED device 12 is 8 to 20 microns. In this embodiment, the size of the Micro-LED device 12 is 20 microns. The size of the Micro-LED device 12 is micron-level, so that the monolithic integrated Micro-LED chip 100 of the same size has more Micro-LED devices 12, improves the efficiency of the monolithic integrated Micro-LED chip 100, and reduces the size of the monolithic integrated Micro-LED chip 100, which is more conducive to meeting the requirements of miniaturization and low power consumption of Internet of Things technologies such as visible light communication.

[0044] The InGaN / GaN multi-quantum well structure includes multiple InGaN / GaN quantum wells superimposed on each other. The efficient radiation recombination in the InGaN / GaN multi-quantum well structure enables the monolithic integrated Micro-LED chip to output optical signals, thereby improving the luminescence performance of the monolithic integrated Micro-LED chip. Moreover, the InGaN / GaN multi-quantum well structure can improve the electro-optical conversion efficiency, and flexibly control the response to incident light of different wavelengths by adjusting the layer structure of the multi-quantum well structure. Preferably, the logarithm of the InGaN / GaN quantum wells in the InGaN / GaN multi-quantum well structure is 1-20. The InGaN / GaN multi-quantum well structure has a smaller number of quantum well logarithms, which can reduce the transit time of photogenerated carriers and increase the bandwidth.

[0045] The thickness of the quantum barrier in the InGaN / GaN multi-quantum well structure is 0.5-5nm. The ultra-thin quantum barrier thickness can reduce the transit time lifetime of carriers, which is beneficial to improving the bandwidth of the device. In this embodiment, the thickness of the quantum barrier in the InGaN / GaN multi-quantum well structure is 5nm.

[0046] Since both tunneling and thermal electron emission lifetimes decrease with decreasing barrier height, the Micro-LED device 12 with thinner barriers and greater reverse bias has a shorter escape lifetime and thus a higher bandwidth. The Micro-LED device 12 reduces the thickness of the quantum barriers in the InGaN / GaN multi-quantum well structure to reduce the escape lifetime of carriers, which is beneficial to improving the bandwidth of the Micro-LED detector when the monolithic integrated Micro-LED chip 100 is used for light detection.

[0047] The material of the current diffusion layer can be a commonly used material of an existing current diffusion layer, and can be selected according to actual needs. In this embodiment, the current diffusion layer is an indium tin oxide (ITO) layer.

[0048] Preferably, a first electrode layer is deposited on the surface of the current diffusion layer to form a p-contact layer; and a second electrode layer is deposited on the surface of the n-GaN layer to form an n-contact layer. The second electrode layer is spaced apart from the passivation layer. The first electrode layer and the second electrode layer are preferably metal electrode layers. More preferably, the materials of the first electrode layer and the second electrode layer include but are not limited to copper (Cu), aluminum (Al), titanium (Ti), gold (Au), etc. In this embodiment, a Ti-Al-Ti-Au metal layer is deposited on the surface of the ITO layer as the first electrode layer; and a Ti-Al-Ti-Au metal layer is deposited on the surface of the n-GaN layer as the second electrode layer.

[0049] The monolithic integrated Micro-LED chip 100 provides a reverse high bias through a high voltage bias circuit, which not only makes the absorption area of ​​the device almost exhausted, reduces the carrier diffusion time, but also increases the drift speed of the carriers, reduces the transit time, and further increases the bandwidth. The monolithic integrated Micro-LED chip 100 can be used for light detection through a high voltage bias circuit, which can provide a reverse bias voltage of 0V-200V, and the detection bandwidth is 10MHz-10GHz under different voltages; the monolithic integrated Micro-LED chip 100 can also be used for light emission, and the bandwidth for light emission is 10MHz-10GHz.

[0050] See also Figure 3 , is the bandwidth characteristic of the monolithic integrated Micro-LED chip 100 for light detection. The bandwidth characteristic of the 20μm Micro-LED device 12 under different bias voltages was tested using a vector network analyzer (VNA, PicoVNA106). Figure 3 It can be seen that with the increase of bias voltage, the bandwidth of Micro-LED photodetector increases. Micro-LED photodetector can withstand extremely high bias voltage of -70V and exhibit ultra-high bandwidth characteristics under extremely high bias voltage. The maximum bandwidth can reach 2.7GHz under -70V bias voltage.

[0051] See also Figure 4 , which is a current and voltage characteristic diagram when a monolithic integrated Micro-LED chip 100 is used for light detection. The Micro-LED photodetector with a diameter of 20 μm was tested using Keithley 2614B, with no light and a power density of 26.5 W / cm 2 The current-voltage characteristics under the illumination condition. Figure 4 It can be seen that the dark current under zero bias is 10 -11 A level, -30V bias voltage dark current is 10 -8 A level. Under illumination conditions, the photocurrent of a single 20μm Micro-LED photodetector can reach 10 -4 A level. This indicates that when the monolithic integrated Micro-LED chip 100 of the present invention is used for light detection, the photoelectric conversion efficiency is relatively high.

[0052] Preferably, a slightly concave wafer bending condition is maintained during the growth of the InGaN / GaN multiple quantum well structure. The tensile stress generated by the bending can partially compensate for the compressive stress of the InGaN / GaN multiple quantum well structure, which is beneficial to reducing the quantum Stark effect (QCSE) of the Micro-LED device 12. The suppression of QCSE helps to enhance the overlap of electron wave functions and hole wave functions in the InGaN / GaN multiple quantum well structure region, which is beneficial to improving the modulation bandwidth and quantum efficiency of the Micro-LED device 12.

[0053] The passivation layer may be any commonly used passivation layer in a Micro-LED chip, for example, may be but not limited to silicon dioxide (SiO2), silicon nitride (SiN), etc. In this embodiment, the passivation layer is a SiO2 passivation layer.

[0054] In some embodiments, the monolithic integrated Micro-LED chip 100 is used as a narrow-band photodetector, and the narrow-band photodetector exhibits wavelength selectivity, and the spectral responsivity full width at half maximum (FWHM) can be, but is not limited to, 10-50nm. In an optional embodiment, the monolithic integrated Micro-LED chip 100 is used as a narrow-band photodetector, and the narrow-band photodetector exhibits wavelength selectivity at 368-416nm, and the FWHM is 48nm.

[0055] By introducing the InGaN / GaN multi-quantum well structure, the electro-optical conversion efficiency is improved, so that the monolithic integrated Micro-LED chip 100 can well realize the light detection function, and the multi-quantum well structure can also flexibly control the response to incident light of different wavelengths by adjusting the layer structure, thereby increasing the sensitivity and response speed of the photoelectric detection device. Moreover, with the increase of the reverse electric field, the drift velocity of the photogenerated carriers increases, the depletion layer becomes wider, the absorption zone is almost exhausted, the diffusion time of the carriers is cancelled, and the junction capacitance of the device is reduced, thereby increasing the modulation bandwidth of the photoelectric detection device, so that the photoelectric detection device has excellent photoelectric response characteristics under extremely high reverse bias. Avoid the technical problems in the prior art that the stimulated transition of electrons in ordinary pn junction photodetectors only occurs near the pn junction, the electro-optical conversion efficiency is very low, and the response speed is also relatively slow.

[0056] In some embodiments, the monolithic integrated Micro-LED chip 100 is used in high-speed visible light communication, the bandwidth of the monolithic integrated micron-level light emitting diode chip is greater than or equal to 100 MHz, and the communication rate of the high-speed visible light communication is greater than or equal to 10 Gbps. In some optional embodiments, the monolithic integrated Micro-LED chip 100 is used in high-speed visible light communication, the bandwidth of the monolithic integrated micron-level light emitting diode chip is greater than or equal to 100 MHz and less than or equal to 10 GHz, and the communication rate of the high-speed visible light communication is greater than or equal to 10 Gbps and less than or equal to 100 Gbps.

[0057] See also Figure 5 The second embodiment of the present invention provides a visible light communication device 200, the transmitting end of which adopts a monolithic integrated Micro-LED chip 100. The visible light communication device 200 includes a signal modulation unit, a signal generation unit, a signal mixing unit, a micro-LED light source, a lens series, a photodetector, a signal receiving unit and a signal processing unit. Among them, the micro-LED light source is a monolithic integrated Micro-LED chip 100, including all the technical features of the monolithic integrated Micro-LED chip 100 described in the first embodiment, which will not be repeated here.

[0058] The signal modulation unit may adopt, but is not limited to, an intensity modulation (IM) and direct detection (DD) non-coherent system. The signal modulation method includes, but is not limited to, OOK modulation (on-off keying modulation technology), OFDM modulation (orthogonal frequency division multiplexing modulation technology), PAM modulation, etc.

[0059] The signal generating unit may be, but is not limited to, a waveform generator and a digital-to-analog converter (DAC) of various signals. The signal generating unit generates an electrical signal using a modulated digital signal to complete the digital-to-analog conversion. The generated AC signal will be combined with the DC signal to drive a single Micro-LED device on the monolithic integrated Micro-LED chip 100. Preferably, the signal generating unit sends a symbol rate (baud rate) of 0 to 10 Gbaut / s.

[0060] The signal mixing unit has multiple ports for mixing single or multiple modulated signals and DC signals; among them, the "RF" port inputs the analog signal generated by the digital-to-analog conversion unit, the "DC" port inputs the DC signal, and the output port is connected to the monolithic integrated Micro-LED chip 100 to output a driving signal combining the above two.

[0061] The signal mixing unit may be, but is not limited to, a T-type bias tee, and may also be other types of multi-port signal mixing devices.

[0062] The lens series includes but is not limited to the collimating lens of the micro-LED light source at the transmitting end and the focusing lens of the photodetector at the receiving end, which can be used to collimate the light beam to minimize the light spot reaching the photodetector, thereby maximizing the received light power.

[0063] The photodetector preferably uses a high-sensitivity photodetector to receive light signals and convert them into electrical signals. The photodetector includes but is not limited to avalanche photodiodes, PIN photodiodes, photomultiplier tubes, Schottky photodiodes, and the like.

[0064] The signal receiving unit is an analog-to-digital converter (ADC), which is used to receive the electrical signal obtained by the photodetector, complete analog-to-digital conversion, obtain signal waveform information, and export the received data file. The signal receiving unit can be various types of high-speed oscilloscopes, signal quality analyzers, and other analog-to-digital converters.

[0065] The signal processing unit includes a post-equalizer and a demodulation unit. The post-equalizer uses an equalization algorithm to process the distorted received signal and compensate for the non-ideality of the channel transmission in order to restore the original data. The demodulation unit restores the input data after the equalizer according to the demodulation algorithm of different modulation methods, and obtains information such as the bit error rate and signal-to-noise ratio of the signal through calculation.

[0066] The working principle of the visible light communication device 200 of this example is as follows: when the system components are completely normal, a complete optical path is built, and then the original binary data is encoded and modulated by a signal modulation unit, and the modulated signal is combined with a DC signal to drive a single Micro-LED device 12 on the monolithic integrated Micro-LED chip 100; at the receiving end, a photodetector is used to receive the optical signal and convert it into an electrical signal, and the signal processing unit equalizes the collected data and then demodulates and decodes it to achieve data recovery. In addition, in the visible light communication device 200, the monolithic integrated Micro-LED chip 100 is operated within a limited range, and in order to optimize the received optical signal, a collimating lens and a focusing lens are used to maximize the received optical power.

[0067] It can be understood that when the monolithically integrated Micro-LED chip 100 is used as the transmitting end of the visible light communication device, the structure of the visible light communication device is not limited to the structure of the visible light communication device 200, and can be any visible light communication device in the prior art. As long as the transmitting end adopts the monolithically integrated Micro-LED chip 100, other components in the visible light communication device can adopt common components in the prior art.

[0068] A single micron-sized light emitting diode device in the monolithic integrated Micro-LED chip 100 of the present invention is used as the transmitting end of a visible light communication device. The -3dB modulation bandwidth of the single micron-sized light emitting diode device is 10MHz to 10GHz, and the communication rate of the visible light communication device reaches 1-100Gbps.

[0069] See also Figure 6The third embodiment of the present invention provides a visible light communication device 300, and the receiving end of the visible light communication device 300 adopts a monolithic integrated Micro-LED chip 100. The visible light communication device 300 includes a signal modulation unit, a signal generation unit, a first amplifier, a first DC bias circuit, a laser diode, a lens, an objective lens, a monolithic integrated Micro-LED chip 100, a second DC bias circuit, a second amplifier, a signal receiving unit, and a signal receiving unit. The monolithic integrated Micro-LED chip 100 includes all the technical features of the monolithic integrated Micro-LED chip 100 described in the first embodiment, which will not be repeated here.

[0070] The signal modulation unit and the signal generation unit may include but are not limited to a waveform generator, a voice signal, a video signal, etc. The working principle of the visible light communication device 300 is as follows: the signal modulation unit and the signal generation unit are used to provide a communication signal source, which is amplified by the first amplifier and mixed with the DC signal in the first DC bias circuit; the laser diode is used as the transmitting end to send visible light; a lens and an objective lens are used between the laser diode and the monolithic integrated Micro-LED chip 100 to collimate the emitted light and focus the received light; the light is incident on the monolithic integrated Micro-LED chip 100 for light reception, and the optical signal is converted into an electrical signal; the rear end of the monolithic integrated Micro-LED chip 100 is connected to the second DC bias circuit to provide a negative bias voltage for the monolithic integrated Micro-LED chip 100; the electrical signal is sent to the signal receiving unit through the second amplifier, and the signal receiving unit can be but is not limited to an oscilloscope, a signal quality analyzer, and other digital-to-analog converters; the signal processing unit demodulates the signal received by the monolithic integrated Micro-LED chip 100.

[0071] In this embodiment, a 405nm laser diode is used as a light transmitter for visible light communication; an orthogonal frequency division multiplexing (OFDM) modulation scheme is adopted, and the modulated signal is amplified by a first amplifier and then mixed with a DC signal in a first DC bias circuit, and the modulated emission light is transmitted by the laser diode through a free space distance of 0.3m; the receiving end adopts a single Micro-LED device 12 with a diameter of 20μm on a monolithic integrated Micro-LED chip 100 for light reception; a second DC bias circuit is connected to the rear end of the monolithic integrated Micro-LED chip 100, and a Keithley 2614B current source is used to provide a negative bias voltage for the Micro-LED, and a bias voltage of -70V is used for the monolithic integrated Micro-LED chip 100; the signal receiving unit and the signal processing unit use an oscilloscope to detect the signal received by the monolithic integrated Micro-LED chip 100, and restore the input data by demodulating the code, and obtain information such as the bit error rate and signal-to-noise ratio of the signal through calculation.

[0072] It can be understood that Micro-LED devices 12 of different sizes in the monolithic integrated Micro-LED chip 100 can all be used as receiving ends, and are not limited to the single Micro-LED device 12 of 20μm in this embodiment. For example, single Micro-LED devices 12 of other sizes such as 8μm, 10μm, 12μm, 15μm in diameter can all be used as receiving ends.

[0073] The negative bias voltage provided to the monolithic integrated Micro-LED chip 100 is not limited to -70V in this embodiment, and can be selected according to actual needs. For example, the receiving end of the visible light communication device uses a monolithic integrated Micro-LED chip 100, and the negative bias voltage provided to the monolithic integrated Micro-LED chip 100 can be -200 to 0V.

[0074] A single micron-sized light emitting diode device in the monolithic integrated Micro-LED chip 100 of the present invention is used as the receiving end of the visible light communication device. The -3dB modulation bandwidth of the single micron-sized light emitting diode device is 10MHz to 10GHz, and the communication rate of the visible light communication device can reach 1-100Gbps.

[0075] See also Figure 7 , showing the rate and bit error rate characteristics obtained when a single 20μm Micro-LED device 12 is used as a receiving end in a visible light communication device. The bit error rate characteristics at different transmission rates are tested. When the bit error rate is lower than the forward error correction threshold of 3.8×10 -3 When a single Micro-LED device 12 is used as a receiving end, the maximum rate that can be obtained is 12.8 Gbps, which can achieve Gbps high-speed communication.

[0076] It can be understood that when the monolithic integrated Micro-LED chip 100 is used as the receiving end of the visible light communication device, the structure of the visible light communication device is not limited to the structure of the visible light communication device 300, and can be any visible light communication device in the prior art. As long as the receiving end adopts the monolithic integrated Micro-LED chip 100, other components in the visible light communication device can adopt common components in the prior art.

[0077] See also Figure 8The fourth embodiment of the present invention provides a visible light communication device 400, wherein the relay end of the visible light communication device 400 adopts a monolithic integrated Micro-LED chip 100. The visible light communication device 400 includes a signal modulation unit, a signal generation unit, a signal mixing unit, a laser diode, a lens series 1, a monolithic integrated Micro-LED chip 100, a DC bias circuit, an amplifier, a lens series 2, a photodetector, a signal receiving unit, and a signal processing unit.

[0078] The signal modulation unit may adopt, but is not limited to, an intensity modulation (IM) and direct detection (DD) non-coherent system, and the signal modulation method includes, but is not limited to, OOK modulation, OFDM modulation, PAM modulation, and the like.

[0079] The signal generating unit may be, but is not limited to, a waveform generator and a digital-to-analog converter (DAC) of various signals. The signal generating unit generates an electrical signal using a modulated digital signal to complete digital-to-analog conversion, and the generated AC signal is combined with a DC signal to drive the Micro-LED device.

[0080] Preferably, the signal generating unit sends a symbol rate (baud rate) of 0 to 10 Gbaut / s.

[0081] The signal mixing unit has multiple ports for mixing single or multiple modulated signals and DC signals; the "RF" port inputs the analog signal generated by the digital-to-analog conversion unit, the "DC" port inputs the DC signal, and the output port is connected to the laser diode to output a driving signal combining the above two.

[0082] The signal mixing unit may be, but is not limited to, a T-type bias tee, and may also be other types of multi-port signal mixing devices.

[0083] The lens series 1 includes but is not limited to the collimating lens of the laser diode at the transmitting end and the focusing lens of the monolithic integrated micro-LED chip 100 at the receiving end, which can be used to focus the light beam to minimize the light spot reaching the monolithic integrated micro-LED chip 100, thereby maximizing the received light power.

[0084] Lens series 2 includes but is not limited to the collimating lens of the monolithically integrated Micro-LED chip 100 and the focusing lens of the receiving end photodetector, which can be used to collimate the light beam to minimize the light spot reaching the photodetector, thereby maximizing the received light power.

[0085] The photodetector preferably uses a high-sensitivity photodetector to receive light signals and convert them into electrical signals. The photodetector includes but is not limited to avalanche photodiodes, PIN photodiodes, photomultiplier tubes, Schottky photodiodes, and the like.

[0086] The signal receiving unit is an analog-to-digital converter (ADC), which is used to receive the electrical signal obtained by the photodetector, complete analog-to-digital conversion, obtain signal waveform information, and export the received data file. The signal receiving unit can be various types of high-speed oscilloscopes, signal quality analyzers, and other analog-to-digital converters.

[0087] The signal processing unit includes a post-equalizer and a demodulation unit. The post-equalizer uses an equalization algorithm to process the distorted received signal and compensate for the non-ideality of the channel transmission in order to restore the original data. The demodulation unit restores the input data after the equalizer according to the demodulation algorithm of different modulation methods, and obtains information such as the bit error rate and signal-to-noise ratio of the signal through calculation.

[0088] The working principle of the visible light communication device 400 of this embodiment is as follows: first, a laser diode is used as the transmitting end, and then the original binary data is coded and modulated, and the modulated signal is combined with the DC signal to drive the laser diode; at the relay end, a single Micro-LED device 12 on the monolithic integrated Micro-LED chip is used as a photodetector to receive the optical signal and convert it into an electrical signal, and the collected signal is amplified by an amplifier, and then combined with the DC signal to drive another single Micro-LED device 12 on the monolithic integrated Micro-LED chip 100; at the receiving end, a photodetector is used to receive the optical signal and convert it into an electrical signal, and the collected data is post-processed, and then demodulated and decoded to realize data recovery. In addition, in this system, in order to optimize the received optical signal, a lens and an objective lens are used to maximize the received optical power.

[0089] It can be understood that when the monolithic integrated Micro-LED chip 100 is used as a relay end of a visible light communication device, the structure of the visible light communication device is not limited to the structure of the visible light communication device 400, and can be any visible light communication device in the prior art. As long as the relay end adopts the monolithic integrated Micro-LED chip 100, other components in the visible light communication device can adopt common components in the prior art.

[0090] The monolithic integrated Micro-LED chip provided by the present invention can not only carry the functions of light signal emission, reception, modulation and processing, but also can show excellent photoelectric response characteristics and modulation bandwidth under extremely high reverse bias. The monolithic integrated Micro-LED chip provided by the present invention can be used for light detection through a high-voltage bias circuit, and the high-voltage bias circuit can provide a reverse bias voltage of 0V-200V, and the detection bandwidth is 10MHz-10GHz under different voltages; the monolithic integrated micron-level light-emitting diode chip can also be used for light emission, and the bandwidth for light emission is 10MHz-10GHz. The thickness of the quantum barrier in the monolithic integrated Micro-LED chip of the present invention is 0.5-5nm, and the ultra-thin quantum barrier thickness can reduce the transit time lifetime of the carriers, which is beneficial to improve the bandwidth of the device. When the monolithic integrated Micro-LED chip of the present invention is used as a narrow-band photodetector, the narrow-band photodetector exhibits wavelength selectivity and can achieve narrow-band spectral response, and the spectral response half-maximum full width (FWHM) is only 10-50nm. Micro-LED narrow-band photodetectors can be widely used in fields such as color imaging and target recognition. Moreover, when the monolithic integrated Micro-LED chip is used in high-speed visible light communication, the bandwidth of the monolithic integrated micron-level light-emitting diode chip is greater than 100MHz, and the communication rate of high-speed visible light communication is greater than or equal to 10Gbps. The monolithic integrated Micro-LED chip of the present invention can not only be used as the transmitting end and the receiving end in the visible light communication system to achieve high-speed communication up to 100Gbps, but also can be used as a relay end in the visible light communication system to expand the coverage of visible light communication, reduce the probability of link interruption, and improve the reliability and security of the visible light communication system. In addition, the size of each Micro-LED device is in the micron level, which effectively reduces the size and overall power consumption of the photonic integrated system.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A monolithically integrated micron-scale light-emitting diode chip, characterized in that: include: A substrate and a plurality of micron-sized light-emitting diode devices distributed in an array on the substrate, each of the micron-sized light-emitting diode devices comprising an n-GaN layer, an InGaN / GaN multi-quantum well structure, a p-AlGaN layer, a p-GaN layer and a current diffusion layer stacked in sequence, and a passivation layer located on the sides of the InGaN / GaN multi-quantum well structure, the p-AlGaN layer, the p-GaN layer and the current diffusion layer, the quantum barrier thickness in the InGaN / GaN multi-quantum well structure is 0.5-5nm, the monolithic integrated micron-sized light-emitting diode chip can be used for light detection through a high-voltage bias circuit, the high-voltage bias circuit can provide a reverse bias voltage of 0V-200V, and the detection bandwidth under different voltages is 10MHz-10GHz; the monolithic integrated micron-sized light-emitting diode chip can also be used for light emission, and the bandwidth when used for light emission is 10MHz-10GHz.

2. The monolithically integrated micron-sized light-emitting diode chip according to claim 1, characterized in that: The number of quantum well pairs in the InGaN / GaN multiple quantum well structure is 1-20.

3. The monolithically integrated micron-sized light emitting diode chip according to claim 1, characterized in that: A first electrode layer is arranged on the surface of the current diffusion layer to form a p-contact layer; a second electrode layer is arranged on the surface of the n-GaN layer to form an n-contact layer, and the second electrode layer is arranged spaced apart from the passivation layer.

4. The monolithically integrated micron-sized light emitting diode chip according to claim 3, characterized in that: The first electrode layer is a Ti—Al—Ti—Au metal layer and / or the second electrode layer is a Ti—Al—Ti—Au metal layer.

5. The monolithically integrated micron-sized light-emitting diode chip according to any one of claims 1 to 4, characterized in that: The size of each micrometer-sized light-emitting diode device is 1-100 micrometers.

6. An application of the monolithically integrated micron-sized light-emitting diode chip according to any one of claims 1 to 5 as a narrow-band photodetector, characterized in that: The narrow-band photodetector exhibits wavelength selectivity, and the full width at half maximum of the spectral response is 10-50nm.

7. A visible light communication device, characterized in that: The transmitting end, the relay end, or the receiving end of the visible light communication device adopts the monolithic integrated micron-level light emitting diode chip as described in any one of claims 1-5.

8. The visible light communication device according to claim 7, characterized in that: A single micron-sized light emitting diode device is used as a transmitting end of a visible light communication device, and a -3dB modulation bandwidth of the single micron-sized light emitting diode device is 10MHz to 10GHz.

9. The visible light communication device according to claim 7 or 8, characterized in that: A single micron-sized light emitting diode device is used as a transmitting end of a visible light communication device, and the communication rate of the visible light communication device reaches 1-100 Gbps.

10. The visible light communication device according to claim 7, characterized in that: A single micron-sized light emitting diode device is used as the receiving end of the visible light communication device, and the -3dB modulation bandwidth of the single micron-sized light emitting diode device is 10MHz to 10GHz.

11. The visible light communication device according to claim 7 or 10, characterized in that: A single micron-sized light emitting diode device is used as the receiving end of the visible light communication device, and the communication rate of the visible light communication device reaches 1-100 Gbps.

12. An application of the visible light communication device according to claim 7 in high-speed visible light communication, characterized in that: The bandwidth of the monolithically integrated micron-sized light-emitting diode chip is greater than or equal to 100 MHz, and the communication rate of the high-speed visible light communication is greater than or equal to 10 Gbps.

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