Single Rh @ ZnO micron line heterojunction ultraviolet-enhanced light-emitting diode and preparation method and application thereof
Technical Field
The invention relates to a single Rh @ ZnO micron line heterojunction ultraviolet-enhanced light-emitting diode and a preparation method and application thereof, belonging to the technical field of semiconductor optoelectronic devices.
Background
The semiconductor ultraviolet light source has great application value in the fields of illumination, sterilization, medical treatment, biochemical detection, high-density information storage, secret communication and the like. Zinc oxide (ZnO) is an important II-VI semiconductor material, and has wide application in ultraviolet light-emitting diodes, laser diodes and other aspects due to the wide forbidden band width (3.7 eV), relatively high exciton confinement energy (60 meV), high crystallization quality and perfect optical resonant cavity. However, since the ZnO material itself has a large number of zinc interstitial and oxygen vacancy defects, p-type doping is difficult, and the light emitting efficiency is low because the effective injection rate of carriers is low and stability is poor. Therefore, there is a need for an ultraviolet-enhanced light emitting diode, a method for manufacturing the same, and an application of the same, which can improve the effective injection of electrons.
Disclosure of Invention
The invention aims to solve the technical problem that the invention provides a single Rh @ ZnO micron line heterojunction ultraviolet-enhanced light-emitting diode, wherein an n-Rh @ ZnO single micron line of the light-emitting diode and a p-GaN substrate form an effective heterojunction structure, the I-V characteristic of the heterojunction shows the characteristic of a rectifier diode, and the single Rh @ ZnO micron line heterojunction presents efficient and stable ultraviolet light emission under forward bias, so that the enhancement of the ultraviolet-enhanced light-emitting diode is realized, and the application of the LED in the field of ultraviolet light sources is promoted.
Meanwhile, the invention provides a preparation method of a single Rh @ ZnO microwire heterojunction ultraviolet-enhanced light emitting diode, which selects P-GaN as a P-type substrate, the P-type substrate and a ZnO material construct an effective heterojunction structure, and meanwhile, by utilizing the superior ultraviolet surface plasmon near field enhancement characteristic and the field locality of a metal Rh nano structure, a one-dimensional enhanced resonant cavity is constructed on the surface of ZnO by spin-coating ultraviolet Rh nano particles, so that the effective injection of electrons is improved, and the construction of the ultraviolet-enhanced light emitting diode is realized.
Meanwhile, the invention provides application of the single Rh @ ZnO micron line heterojunction ultraviolet-enhanced light-emitting diode in light-emitting devices, light detection and biosensing.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the single Rh @ ZnO micron line heterojunction ultraviolet enhanced light emitting diode comprises a p-GaN substrate, wherein a Ni/Au electrode is evaporated on one side of the upper surface of the p-GaN substrate, an n-Rh @ ZnO single micron line is arranged on the other side of the upper surface of the p-GaN substrate, and an ITO conductive electrode covers the upper surface of the n-Rh @ ZnO single micron line.
Preferably, ultraviolet Rh nano-particles are spin-coated on the surface of the ZnO micron line in the n-Rh @ ZnO single micron line.
Further preferably, the ZnO microwire is a hexagonal ZnO microwire with good crystalline quality; the ultraviolet Rh nanoparticles are Rh nanoparticles with an LSPR absorption peak of 370 nm.
Preferably, the length, the width and the height of the p-GaN substrate are respectively 1.9-2.0cm, 1.7-1.8 cm and 2-10 micrometers; the length and width of the ITO conductive electrode are 1.0-1.2 cm and 1.7-1.8 cm; the thickness of the Ni/Au electrode is 30-50 nm, and ohmic contact is formed between the Ni/Au electrode and the p-GaN substrate; the length of the n-Rh @ ZnO single micron line is 0.8-1.0 cm.
The preparation method of the single Rh @ ZnO micron line heterojunction ultraviolet-enhanced light-emitting diode comprises the following steps:
s01, annealing and cleaning the p-GaN substrate to ensure the p-GaN substrate to be clean and flat;
s02, preparing the Ni/Au electrode on one side of the p-GaN substrate;
s03, preparing the n-Rh @ ZnO single micron line;
s04, cleaning the ITO conductive electrode and keeping the ITO conductive electrode clean and flat;
s05, placing the n-Rh @ ZnO single micron line obtained in the S03 on the p-GaN substrate obtained in the S02, placing the cleaned ITO conductive electrode on the n-Rh @ ZnO single micron line and fixing to form a p-GaN/n-Rh @ ZnO heterojunction structure, namely, the construction of the single Rh @ ZnO micron line heterojunction ultraviolet-enhanced light-emitting diode is realized.
Preferably, in S01, firstly, the p-GaN substrate is placed in a high-temperature furnace at the temperature of 750-850 ℃ for annealing for 2-2.5 h; then, the mixture is respectively washed by acetone, ethanol and deionized water for a plurality of times and dried for standby.
Preferably, in S02, most of the p-GaN substrate is covered with a mask plate, and the Ni/Au electrode is evaporated on the front surface of the exposed end of the p-GaN substrate by an electron beam evaporation method.
Preferably, in S03, Rh nanoparticles with an LSPR absorption peak of 370nm are spin-coated on the surface of a hexagonal n-ZnO microwire with good crystallization quality, and then the hexagonal n-ZnO microwire is placed in an oven at 100-120 ℃ to be heated for 1-1.5 h, so that the Rh nanoparticles and the n-ZnO microwire are fully combined, and the n-Rh @ ZnO microwire composite structure is prepared, wherein the concentration of the Rh nanoparticles is 0.1-0.2 g/mL, and the solvent is alcohol. Measured by absorption spectrum, the corresponding absorption peak is 0.8-0.1 (a.u.).
Preferably, the p-GaN substrate has a hole concentration of 1.4 × 1019~2.0×1019/cm3Hole mobility of 10-100 cm2V.s; the electron concentration of the n-ZnO micron line is 1 multiplied by 1017~1×1019/cm3Electron mobility of 5-100 cm2/V·s。
The application of the single Rh @ ZnO micron line heterojunction ultraviolet enhanced light emitting diode in light emitting devices, optical detection and biosensing is provided.
The invention has the following beneficial effects:
1. according to the invention, an effective heterojunction structure is formed by a single n-ZnO microwire with high crystallization quality and p-GaN, and the unique ultraviolet surface plasmon characteristic of metal Rh is utilized to confine the maximum range of photon energy in a nanoscale microstructure, so that long-range transmission of photon energy and effective injection of electrons are realized, and thus the Rh @ ZnO microwire heterojunction ultraviolet-enhanced light-emitting diode is constructed.
2. In the invention, the Ni/Au electrode and the p-GaN substrate form ohmic contact and are used as the anode of the heterojunction; the ITO conductive electrode is in good contact with the n-Rh @ ZnO single microwire and serves as a cathode of a heterojunction, and therefore the Rh @ ZnO microwire heterojunction ultraviolet-enhanced light-emitting diode is constructed.
3. According to the invention, by designing the Rh @ ZnO composite structure and constructing the n-Rh @ ZnO/p-GaN heterojunction structure, under the condition of forward bias, obvious ultraviolet enhancement is realized. According to the invention, by spin coating metal Rh nanoparticles with ultraviolet surface plasmon characteristics and utilizing Rh ultraviolet surface plasmon resonance characteristics, the problem of ZnO micron linear heterojunction-based ultraviolet luminescence is greatly improved, and the construction of a single ZnO micron linear heterojunction-based ultraviolet-enhanced light-emitting diode is realized.
Drawings
FIG. 1 is a schematic structural diagram of a single Rh @ ZnO microwire heterojunction ultraviolet-enhanced light-emitting diode of the present invention;
FIG. 2 is an I-V characteristic curve of a single Rh @ ZnO microwire heterojunction ultraviolet-enhanced light-emitting diode of the present invention;
FIG. 3 is a photograph of luminescence of a comparative example n-ZnO/p-GaN heterojunction (a) and an n-Rh @ ZnO/p-GaN heterojunction (b) of the present invention;
FIG. 4 is a graph comparing the luminescence spectra of the comparative example n-ZnO/p-GaN heterojunction and the inventive n-Rh @ ZnO/p-GaN heterojunction at the same injection current (1.2 mA).
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting.
Example 1:
as shown in figure 1, a single Rh @ ZnO micron-line heterojunction ultraviolet-enhanced light-emitting diode adopts a p-GaN substrate 1, the size is 1.9 multiplied by 1.7cm, the thickness is 2-10 um, and the hole concentration is 1.4 multiplied by 1019~2.0 ×1019/cm3Hole mobility of 10-100 cm2V.s; the thickness of the Ni/Au electrode 3 on the p-GaN substrate 1 is 36 nm; the electron concentration of the n-ZnO micron line is 1 multiplied by 1017~1×1019/cm3Electron mobility of 5-100 cm2V.s; the length of the n-ZnO micron line is 0.8cm, the concentration of the adopted Rh nano-particles is 0.15g/mL, and the ITO conductive electrode 4The dimensions were 1.0cm by 1.7 cm.
Specifically, the single Rh @ ZnO nanowire heterojunction ultraviolet-enhanced light emitting diode of the embodiment includes a p-GaN substrate 1, a Ni/Au electrode 3 is evaporated on one side of the upper surface of the p-GaN substrate 1, an n-Rh @ ZnO single nanowire 2 is placed on the other side of the upper surface of the p-GaN substrate 1, and an ITO conductive electrode 4 covers the upper surface of the n-Rh @ ZnO single nanowire 2.
Ultraviolet Rh nano-particles are coated on the surface of the ZnO micron line in the n-Rh @ ZnO single micron line 2 in a spinning mode.
The ZnO micron line is a hexagonal ZnO micron line with good crystallization quality; the ultraviolet Rh nanoparticles are Rh nanoparticles with an LSPR absorption peak of 370 nm.
Example 2:
the preparation method of the single Rh @ ZnO micron line heterojunction ultraviolet-enhanced light-emitting diode comprises the following steps:
s01, annealing and cleaning the p-GaN substrate 1 to ensure the p-GaN substrate to be clean and flat;
s02, preparing the Ni/Au electrode 3 on one side of the p-GaN substrate 1;
s03, preparing the n-Rh @ ZnO single micron line 2;
s04, cleaning the ITO conductive electrode 4 and keeping the ITO conductive electrode clean and flat;
s05, placing the n-Rh @ ZnO single micron line 2 obtained in the S03 on the p-GaN substrate 1 obtained in the S02, and placing and fixing the cleaned ITO conductive electrode 4 on the n-Rh @ ZnO single micron line 2 to form a p-GaN/n-Rh @ ZnO heterojunction structure, namely, the construction of the single Rh @ ZnO micron line heterojunction ultraviolet enhanced light emitting diode is realized.
In S01, firstly, the p-GaN substrate 1 is placed in a high-temperature furnace at 800 ℃ for annealing for 2 h; then, the mixture is respectively washed by acetone, ethanol and deionized water for a plurality of times and dried for standby.
In S02, a mask plate is used to cover most of the p-GaN substrate 1, only a small portion of one end is exposed, the Ni/Au electrode 3 is evaporated on the front surface of the exposed end of the p-GaN substrate 1 by an electron beam evaporation method, and the conduction state between the Ni/Au electrode 3 and the p-GaN substrate 1 is tested to determine ohmic contact.
In S03, the prepared Rh nanoparticles are cleaned and dispersed in alcohol, absorption spectrum (1a.u.) is combined to determine corresponding concentration (0.15g/mL) for later use, Rh nanoparticles with an LSPR absorption peak of 370nm are spin-coated on the surface of a hexagonal n-ZnO microwire with good crystallization quality (selected under an optical microscope), and then the hexagonal n-ZnO microwire is placed in a 100 ℃ oven to be heated for 1h, so that the Rh nanoparticles and the n-ZnO microwire are fully combined, and a stable n-Rh @ ZnO microwire composite structure, namely n-Rh @ ZnO single microwire 2, is prepared.
In S04, a whole ITO conductive electrode 4 is cut into a plurality of pieces with a size of 1.0cm × 1.7cm, ultrasonically cleaned with acetone, ethanol and deionized water for a plurality of times, and dried for use.
In this embodiment, the new ITO conductive electrode 4 is cleaned with acetone, alcohol (i.e., ethanol), and deionized water; and the used ITO conductive electrode 4 needs to be ultrasonically cleaned for a plurality of times by trichloroethylene, acetone, ethanol and deionized water and then dried for standby, namely the cleaning effect of the old ITO conductive electrode 4 and the trichloroethylene is better.
In S05, operating under an optical microscope, transferring the hexagonal n-Rh @ ZnO single microwire 2 after the Rh nanoparticles are spin-coated in S03 onto a p-GaN substrate 1 by using tweezers, then placing a cleaned ITO conductive electrode 4 on the n-Rh @ ZnO single microwire 2, fixing two ends by using a clamp, and ensuring that the n-Rh @ ZnO single microwire 2 is well contacted with the p-GaN substrate 1 and the n-Rh @ ZnO single microwire 2 is well contacted with the ITO conductive electrode 4, namely constructing the n-Rh @ ZnO/p-GaN heterojunction ultraviolet enhanced light emitting diode.
Next, the above-mentioned steps S01, S02 were repeated, and an n-ZnO/p-GaN heterojunction light emitting diode without spin-coating Rh nano-particles was prepared in the same manner as a comparative example, i.e., an n-ZnO/p-GaN heterojunction.
The rectification properties of n-ZnO/p-GaN and n-Rh @ ZnO/p-GaN heterojunction light-emitting diodes are researched, light-emitting videos of the n-ZnO/p-GaN heterojunction light-emitting diodes and the n-Rh @ ZnO/p-GaN heterojunction light-emitting diodes under different injection currents are shot, light-emitting spectrums are measured, and compared with light-emitting photos and light-emitting spectrums of Rh nanoparticles before and after spin coating, as shown in figures 2, 3 and 4, the light-emitting intensities of the two heterojunction light-emitting diodes are increased along with the increase of the injection currents, the light-emitting intensities of the n-Rh @ ZnO/p-GaN heterojunction ultraviolet-enhanced light-emitting diodes after spin coating of Rh nanoparticles are obviously enhanced more, the light-emitting center wavelength is 392nm in the spectrum, the half-height width is 34nm, and the light.
Example 3:
the application of the single Rh @ ZnO micron line heterojunction ultraviolet enhanced light emitting diode in light emitting devices, optical detection and biosensing is provided.
Example 4:
this example differs from example 2 only in that:
a single Rh @ ZnO micron line heterojunction ultraviolet enhanced light emitting diode adopts a p-GaN substrate 1, the size is 2.0 multiplied by 1.8cm, and the thickness of a Ni/Au electrode 3 on the p-GaN substrate 1 is 50 nm; the length of the n-ZnO micron line is 1.0cm, the concentration of the adopted Rh nano-particles is 0.1g/mL, and the size of the ITO conductive electrode 4 is 1.2cm multiplied by 1.8 cm.
A preparation method of a single Rh @ ZnO micron-line heterojunction ultraviolet-enhanced light-emitting diode is characterized in that in S01, a p-GaN substrate 1 is placed in a high-temperature furnace at 750 ℃ to be annealed for 2.5 hours. In S03, the obtained product is placed in an oven at 120 ℃ and heated for 1.5h after spin coating.
Example 5:
this example differs from example 2 only in that:
the thickness of the Ni/Au electrode 2 is 30nm, and the concentration of the adopted Rh nano-particles is 0.2 g/mL.
A preparation method of a single Rh @ ZnO micron-line heterojunction ultraviolet-enhanced light-emitting diode is characterized in that in S01, a p-GaN substrate 1 is placed in a high-temperature furnace at 850 ℃ to be annealed for 2.2 hours. In S03, the obtained product is placed in a 110 ℃ oven to be heated for 1.2h after spin coating.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.