High-stability micro / nano plasma device

Abstract

The invention provides a high-stability micro / nano plasma device, and belongs to the technical field of millimeter wave terahertz devices. The device comprises an insulating substrate, a wide bandgap semiconductor anode, an ohmic contact electrode, an ion impact barrier layer and a wide bandgap semiconductor cathode, the micro / nano plasma device is of a horizontal structure, and a wide bandgap semiconductor anode is arranged in a right region above the insulating substrate; a wide bandgap semiconductor cathode with a convex structure is arranged in a left side area above the insulating substrate; ohmic contact electrodes are arranged above the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode. A nano / micron air channel is arranged between the cathode and the anode of the wide bandgap semiconductor; and the ion impact barrier layer is arranged between the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode. The wide bandgap semiconductor is used as the electrode, electron emission is enhanced, the ion impact resistance of the electrode is improved, the barrier layer is introduced, ion impact on the electrode is reduced, the stability of the device is remarkably improved, and the service life of the device is remarkably prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of millimeter wave terahertz devices and the technical field of ultrafast devices and high-power devices, and in particular relates to a micro / nanoplasma device with high stability. Background Art

[0002] Micro- / nanoplasmonic devices are plasma devices with air gaps ranging from submicrometers to hundreds of nanometers, capable of operating at room temperature under atmospheric pressure. As a new type of plasma device, micro- / nanoplasmonic devices not only inherit the advantages of traditional plasma devices in terms of extremely high current density, high-temperature resistance, and ionizing radiation resistance, but also integrate semiconductor micro- / nanoprocessing, enabling device miniaturization, high integration, and large-scale batch production. Their basic operating principle is to control the generation and dissipation of plasma. When the voltage between electrodes exceeds the breakdown voltage of the air gap, electron collisions within the gap generate micro- / nanoplasma. The high field in the gap allows for rapid electron transport, enabling ultrafast switching from the off-state to the conducting state, resulting in extremely fast switching speeds and output power. These characteristics make these devices highly promising for applications in pulsed power electronics, ultra-wideband radar, and biomedicine.

[0003] Although micro- / nanoplasmonic devices have garnered widespread attention and demonstrated significant advantages in performance, such as output power and switching speed, they still face challenges in practical application, such as high ion impact energy and electrode damage caused by excessively high turn-on voltages. Currently, there are two mainstream solutions. One is to reduce the device's air gap, lowering the turn-on voltage and reducing the ion impact energy; the other is to use harder metals, such as tungsten (W), and appropriately increase the electrode thickness. However, micro- / nanoplasmonic devices have traditionally used metal electrodes (high conductivity). Both reducing the gap and increasing the thickness of the metal face manufacturing difficulties and increased costs. Summary of the Invention

[0004] The present invention aims to provide a highly stable micro- / nanoplasma device with a gap ranging from hundreds of nanometers to micrometers. This method, which does not rely on expensive nanofabrication equipment, is cost-effective, has high yield, and can be mass-produced on large-area wafers. Through structural design and electrode material selection, the device achieves even higher stability, extending its service life and promoting its practical application. This approach addresses the technical issues in prior art micro- / nanoplasma devices, such as high ion impact energy resulting from excessively high turn-on voltages, electrode damage, and short device life.

[0005] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0006] A high-stability micro / nanoplasma device, comprising an insulating substrate, a wide-bandgap semiconductor anode, an ohmic contact electrode, an ion impact barrier layer, and a wide-bandgap semiconductor cathode;

[0007] The micro / nanoplasma device has a horizontal structure. A wide bandgap semiconductor anode is arranged in the right area above the insulating substrate, and the wide bandgap semiconductor anode serves as the anode; a wide bandgap semiconductor cathode with a raised structure is arranged in the left area above the insulating substrate, and the wide bandgap semiconductor cathode serves as the cathode; an ohmic contact electrode is arranged above the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode; a nano / micrometer air channel is provided between the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode; and an ion impact barrier is arranged between the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode.

[0008] Furthermore, the wide bandgap semiconductor cathode includes a wide bandgap semiconductor cathode raised portion and a wide bandgap semiconductor cathode flat portion; the wide bandgap semiconductor cathode raised portion includes an upper surface of the raised portion, a lower surface of the raised portion and a bottom angle of the raised portion; the width of the upper surface of the raised portion is smaller than the width of the lower surface of the raised portion.

[0009] Furthermore, the scale of the nano / micro air channel is 100nm-10μm.

[0010] Furthermore, the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode as wide bandgap semiconductor electrodes are composed of doped wide bandgap semiconductor materials, including gallium nitride, silicon carbide, and diamond; the wide bandgap semiconductor electrodes are n-type doped.

[0011] Furthermore, the material of the ion impact blocking layer includes an insulating material and a semiconductor material, and the height of the ion impact blocking layer is the same as or slightly higher than the wide bandgap semiconductor electrode.

[0012] Furthermore, the ohmic contact electrode material includes gold, tungsten, copper, and aluminum.

[0013] Compared with the prior art, the present invention has the following beneficial technical effects:

[0014] 1) The present invention uses wide-bandgap semiconductors as the anode and cathode of the device, resulting in a lower work function, enhanced electron emission, significantly lowered device turn-on voltage, reduced ion impact energy, improved electrode resistance to ion impact, and increased device lifespan. Furthermore, wide-bandgap semiconductors inherently possess a high Mohs hardness, making them more resistant to ion impact than metal materials, further extending device lifespan.

[0015] 2) Compared to traditional metal electrode preparation processes, the semiconductor process described in the present invention can achieve smaller electrode gap sizes and thicker wide-bandgap semiconductor electrode materials, thereby significantly reducing the device's turn-on voltage and increasing its service life. On the other hand, unlike the difficulty in controlling stress in metal electrode preparation processes, film preparation methods such as epitaxial growth or physical vapor deposition in the semiconductor process can precisely control growth conditions, fundamentally solving the problem of stress accumulation in metal electrode preparation. Due to the use of semiconductor micro / nano manufacturing processes, the device not only provides excellent electrical performance but also is seamlessly compatible with existing integrated circuit processes, reducing production costs.

[0016] 3) This invention proposes to reduce ion impact on the electrodes by introducing an ion impact barrier and designing and optimizing the cathode structure. This significantly reduces damage to the cathode and anode from ions generated by collisions, protecting the integrity and performance stability of the electrodes and thereby extending the service life of the device electrodes. This design strategy provides reliable guarantees for the long-term stable operation of micro- and nanoplasma devices and significantly improves their reliability and lifespan in practical applications.

[0017] 4) The electrodes used in the present invention are all made of semiconductor materials, which are compatible with semiconductor processes, can achieve smaller air gaps and thicker electrodes, and have the advantages of good repeatability, high integration, and large-scale batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in describing the embodiments of the present invention. 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 these drawings without paying any creative labor.

[0019] Figure 1 This is a schematic front view of a high-stability micro / nanoplasma device according to the present invention.

[0020] Figure 2 This is a schematic top view of the high-stability micro / nanoplasma device of the present invention.

[0021] Figure 3 This is a schematic diagram of the raised portion of the high-stability micro / nanoplasmonic device of the present invention.

[0022] Explanation of the marks in the figure: 11-insulating substrate; 12-wide bandgap semiconductor anode; 13-ohmic contact electrode; 14-ion impact blocking layer; 15-wide bandgap semiconductor cathode raised portion; 16-micro / nano air channel; 17-wide bandgap semiconductor cathode flat portion; 18-upper surface of the raised portion; 19-lower surface of the raised portion; 20-bottom angle of the raised portion. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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 efforts are within the scope of protection of the present invention.

[0024] Semiconductor materials offer processing advantages as electrodes, particularly with the development of wide-bandgap semiconductors such as GaN (gallium nitride) and SiC (silicon carbide), making them feasible for use as electrodes in micro- and nanoplasmonic devices. Compared to silicon and metals, wide-bandgap semiconductors have lower electron affinity and higher Mohs hardness. This not only facilitates electron emission and reduces the device's turn-on voltage, but also allows for higher breakdown voltage and thermal stability, significantly improving electrode life. Furthermore, semiconductor-compatible processes can be utilized to fabricate smaller gaps and thicker electrodes at lower cost. Furthermore, rationally designing the device structure, appropriately reducing the cathode area, and adding a barrier layer to reduce the number of ions striking the device cathode can also improve device stability and life.

[0025] The present invention utilizes the advantages of wide bandgap semiconductor materials to propose a highly stable micro / nanoplasmonic device, such as Figure 1-3 As shown, the micro / nanoplasma device includes an insulating substrate 11, a wide bandgap semiconductor anode 12, an ohmic contact electrode 13, an ion impact barrier 14, and a wide bandgap semiconductor cathode.

[0026] The wide bandgap semiconductor cathode includes a wide bandgap semiconductor cathode raised portion 15 and a wide bandgap semiconductor cathode flat portion 17. The wide bandgap semiconductor cathode raised portion 15 includes a raised upper surface 18, a raised lower surface 19, and a raised bottom corner 20. The width of the raised upper surface 18 is smaller than the width of the raised lower surface 19.

[0027] The micro / nanoplasmonic device has a horizontal structure. A wide-bandgap semiconductor anode 12 is located on the right side of an insulating substrate 11, serving as the anode. A wide-bandgap semiconductor cathode with a raised structure is located on the left side of the insulating substrate 11, serving as the cathode. An ohmic contact electrode 13 is located above the wide-bandgap semiconductor cathode and anode. A nano / micrometer air channel is located between the wide-bandgap semiconductor cathode and anode, with a channel size of 100 nm to 10 μm.

[0028] The wide bandgap semiconductor cathode and wide bandgap semiconductor anode serve as wide bandgap semiconductor electrodes and are composed of doped wide bandgap semiconductor materials, including but not limited to gallium nitride, silicon carbide, and diamond. The manufacturing method is to first perform photolithographic patterning, and then use processes including but not limited to dry etching and photolithographic stripping to obtain the wide bandgap semiconductor electrode; the wide bandgap semiconductor cathode has a raised portion, and the bottom angle of the raised portion is an acute angle or a right angle. The wide bandgap semiconductor electrode can be n-type doped to provide more electrons for field emission, further reduce the operating voltage of the device, reduce the energy of ion impact, and increase the service life of the device. The wide bandgap semiconductor cathode uses a raised structure to reduce the degree of damage to the device cathode by reducing the ion impact area, while reducing the device capacitance and improving the device response speed.

[0029] Materials for the ion impact barrier layer include, but are not limited to, insulating materials and semiconductor materials. The fabrication method involves first patterning the ion impact barrier layer using photolithography, followed by processes including, but not limited to, dry etching and photolithographic stripping to obtain the ion impact barrier layer. The ion impact barrier layer may be positioned, but is not limited to, near the left electrode, near the right electrode, or between the two electrodes. The height of the ion impact barrier layer may be the same as or slightly higher than that of the wide-bandgap semiconductor electrode. The structure of the ion impact barrier layer may include, but is not limited to, triangular, trapezoidal, rectangular, and mesh shapes.

[0030] Ohmic contact electrode materials include, but are not limited to, gold, tungsten, copper, and aluminum. Fabrication involves photolithographic patterning followed by a process including, but not limited to, dry etching and photolithographic lift-off to produce a metal electrode. The metal electrode's function is to form an ohmic contact with the wide-bandgap semiconductor electrode, preventing Schottky contact from forming when the device is connected to an external circuit, which could affect device performance.

[0031] The length of the nano / micrometer air channel ranges from hundreds of nanometers to micrometers, which is much smaller than the length of the air channel of a conventional plasma device (millimeter to meter length). The small-scale air channel allows the device to have a high field under low voltage conditions, and the influence of field emission can no longer be ignored. At this time, a large number of electrons are provided by field emission, which solves the problem that electrons do not have enough distance to undergo collision ionization and the probability of electron avalanche formation is greatly reduced. The working mechanism of the device is the combined effect of secondary electron emission, avalanche effect and field emission. The device operates at atmospheric pressure, and when a voltage is applied between the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode, the wide bandgap semiconductor cathode performs field emission. At this scale, gas breakdown is mainly determined by the field emission process.

[0032] The high-stability micro / nanoplasma device proposed in the present invention is described below with reference to a specific embodiment.

[0033] In this embodiment, the substrate is an insulating sapphire substrate, with an n-type GaN thin film formed on top. The left region serves as a 200nm-thick cathode, with a raised portion angled at 45°. The right region serves as a 200nm-thick anode. An ohmic contact electrode composed of Ti / Pt / Au thin films is placed on the GaN film. A 200nm-thick Al2O3 ion impact barrier is placed between the two electrodes. A micro / nano air channel is formed between the Al2O3 ion impact barrier and the GaN film. The channel length is determined by the photolithography scale; in this embodiment, the device gap is 3µm.

[0034] The device operates as follows: the ohmic contact electrode on the n-type GaN film with the raised portion is grounded, and a positive bias is applied to the ohmic contact electrode on the other side of the n-type GaN film. When the electric field strength in the gap reaches the field emission threshold, the n-type GaN electrode with the raised portion emits a large number of electrons into the air channel through field emission. Because the air gap exceeds the electron mean free path, Townsend avalanche multiplication occurs during electron transport, further increasing the electron concentration. Under the influence of the strong electric field, the ions generated by the collision will collide with the cathode. Due to the presence of the barrier layer, only a portion of the ions will strike the cathode, generating secondary electron emission. Because the cathode is a wide-bandgap semiconductor material with inherent resistance to ion impact, the number of electrons generated by the secondary electron emission effect is small. However, within the nanometer and submicron gaps, the cathode field emission effect can emit a large number of electrons to compensate, ultimately completing the breakdown of the air and forming a low-temperature, stable plasma at atmospheric pressure. The intensity of the field emission in this embodiment is determined by the cathode raised portion, the gap distance, and the doping concentration of the GaN material. The smaller the gap, the sharper the cathode protrusion, the greater the field strength within the gap, and the stronger the field emission effect. The higher the GaN doping concentration, the lower the work function, the higher the material conductivity, the lower the electric field required for field emission, and the lower the micro / nanoplasma turn-on voltage.

[0035] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A high-stability micro / nanoplasmonic device, characterized in that: The micro / nanoplasma device comprises an insulating substrate, a wide bandgap semiconductor anode, an ohmic contact electrode, an ion impact barrier layer, and a wide bandgap semiconductor cathode; The micro / nanoplasma device has a horizontal structure. A wide bandgap semiconductor anode is arranged in the right area above the insulating substrate, and the wide bandgap semiconductor anode serves as the anode; a wide bandgap semiconductor cathode with a raised structure is arranged in the left area above the insulating substrate, and the wide bandgap semiconductor cathode serves as the cathode; an ohmic contact electrode is arranged above the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode; a nano / micrometer air channel is provided between the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode; and an ion impact barrier is arranged between the wide bandgap semiconductor cathode and the wide bandgap semiconductor anode.

2. The high-stability micro / nanoplasma device according to claim 1, characterized in that: The wide bandgap semiconductor cathode includes a wide bandgap semiconductor cathode convex portion and a wide bandgap semiconductor cathode flat portion; the wide bandgap semiconductor cathode convex portion includes an upper surface of the convex portion, a lower surface of the convex portion and a bottom angle of the convex portion; the width of the upper surface of the convex portion is smaller than the width of the lower surface of the convex portion.

3. The high-stability micro / nanoplasma device according to claim 1, characterized in that: The scale of nano / micrometer air channels is 100nm-10μm.

4. The high-stability micro / nanoplasma device according to claim 1, characterized in that: The wide bandgap semiconductor cathode and the wide bandgap semiconductor anode serve as wide bandgap semiconductor electrodes and are composed of doped wide bandgap semiconductor materials, including gallium nitride, silicon carbide, and diamond; the wide bandgap semiconductor electrodes are n-type doped.

5. The high-stability micro / nanoplasma device according to claim 1, characterized in that: The material of the ion impact blocking layer includes insulating material and semiconductor material. The height of the ion impact blocking layer is the same as or slightly higher than the wide bandgap semiconductor electrode.

6. The high-stability micro / nanoplasmonic device according to claim 1, characterized in that: Ohmic contact electrode materials include gold, tungsten, copper, and aluminum.

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