CN113253489A - Terahertz multichannel modulator and preparation method thereof - Google Patents
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- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
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- G02F1/015—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/0009—Materials therefor
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
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- G02F1/0102—Constructional details, not otherwise provided for in this subclass
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- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
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Abstract
The invention discloses a terahertz multichannel modulator and a preparation method thereof, wherein the modulator comprises a substrate and an epitaxial layer, wherein a modulation array, a first Schottky electrode, a second Schottky electrode and an ohmic electrode are arranged on the epitaxial layer, a modulation array element comprises a structural unit, the structural unit is provided with a first opening and a second opening, and the first opening and the second opening are respectively provided with a first high electron mobility transistor and a second high electron mobility transistor; the grid electrodes of the first high electron mobility transistors in each row are connected to the first Schottky electrode through grid electrode feeder lines, and the grid electrodes of the second high electron mobility transistors in each row are connected to the second Schottky electrode through grid electrode feeder lines; the source and drain of each row of first high electron mobility transistors are connected to the ohmic electrode through a source-drain feeder line, and the source and drain of each row of second high electron mobility transistors are connected to the ohmic electrode through a source-drain feeder line. According to the scheme, the terahertz waves of a plurality of frequency points are modulated.
Description
Technical Field
The invention relates to the technical field of terahertz communication, in particular to a terahertz multichannel modulator and a preparation method thereof.
Background
The terahertz wave is an electromagnetic wave between microwave and infrared, the frequency range of the terahertz wave is 0.1-10 THz, and the terahertz wave shows many distinctive electromagnetic characteristics due to the unique frequency band position, so that the terahertz wave can be widely applied to the fields of biomedicine, safety inspection, wireless communication and the like. In recent years, the development of terahertz wireless communication technology is heading toward high speed and long distance, but the development thereof is limited to some extent due to the lack of high-performance key devices. The terahertz modulator is one of the key devices, and the improvement of the performance of the terahertz modulator plays a crucial role in the development of the terahertz communication technology, so that the terahertz modulator becomes a research hotspot in recent years. Since 2004, successive articles related to external terahertz modulators were published in numerous international top-level journal of science, and the contents of the articles include doped semiconductor substrates, phase change materials, graphene and the like, which are combined with metamaterials, and the modulation of terahertz waves propagating in free space is realized by using excitation modes such as external temperature, illumination, electric fields and the like, so that the modulators can be divided into temperature control, light control and electric control modulators. The electronic control modulator has the characteristic of easy integration and has important application in the field of terahertz communication. In 2006, H-T Chen et al propose an electronic control terahertz modulator based on an open resonant ring metamaterial structure, a metal metamaterial structure is in contact with a gallium arsenide substrate to form a Schottky diode structure, and a certain voltage is loaded between ohmic contact and the metal structure of the device, so that modulation of incident terahertz waves can be realized. In 2011, a research team of boston university provides a composite electronic control terahertz modulator based on an open resonator ring metamaterial structure and a HEMT, the concentration of two-dimensional electron gas in a channel of the HEMT is changed by adding grid voltage, the resonance strength of the metamaterial structure is changed, and then the terahertz wave is regulated and controlled. In 2015, a research team of electronics science and technology university provides a composite metamaterial structure based on an I-shaped metamaterial structure and an HEMT, and the modulation rate of the composite metamaterial structure can reach 1 GHz. In 2017, ZHENZHou et al propose a terahertz modulator based on a four-opening resonant ring metamaterial structure combined with an HEMT, and under the drive of-4V grid voltage, the modulation depth can reach 80%, and the modulation rate can reach 2.7 MHz. Although the modulator has higher modulation depth and modulation rate, the modulator has only one working channel, namely, only one independent frequency band can realize modulation. In the field of communications, in order to improve communication rate, communication capacity, and communication quality, it is often required to modulate signals in each communication band independently. Based on this, the aforementioned modulator has difficulty meeting the above-mentioned communication application requirements.
Disclosure of Invention
The invention aims to provide a terahertz multichannel modulator, which at least solves the technical problem that the communication rate, the communication capacity and the communication quality cannot be further improved because the existing terahertz modulator only has one working channel, namely only one independent frequency band can realize modulation.
The invention is realized by the following technical scheme:
the invention provides a terahertz multichannel modulator which comprises a semiconductor substrate and an epitaxial layer positioned on the semiconductor substrate, wherein a modulation array, a first Schottky electrode, a second Schottky electrode and an ohmic electrode are arranged on the epitaxial layer, the modulation array is formed by M multiplied by N modulation array elements in periodic arrangement, M is the longitudinal arrangement period number of the modulation array elements, N is the transverse arrangement period number of the modulation array elements, M is more than or equal to 3, N is more than or equal to 3, the modulation array elements comprise a structural unit, the structural unit is provided with a first opening and a second opening, and a first high electron mobility transistor and a second high electron mobility transistor are respectively arranged at the first opening and the second opening; wherein the content of the first and second substances,
the grid electrode of the first high electron mobility transistor of each row of modulation array elements is connected to the first Schottky electrode through a first grid electrode feeder line, and the grid electrode of the second high electron mobility transistor of each row of modulation array elements is connected to the second Schottky electrode through a second grid electrode feeder line;
and the source electrode and the drain electrode of the first high electron mobility transistor of each row of modulation array elements are connected to the ohmic electrode through a first source drain feeder line, and the source electrode and the drain electrode of the second high electron mobility transistor of each row of modulation array elements are connected to the ohmic electrode through a second source drain feeder line.
Further, the structural unit is a metamaterial structural unit.
Further, the constitutional unit is I type constitutional unit, the constitutional unit includes the montant of entablature, sheer pole and connection sheer pole, first opening and second opening are located the montant, first opening and second opening are cut into montant, well montant and lower montant with the montant, the entablature is first source leakage feeder, and the sheer pole is the second source leakage feeder, the source electrode and the drain electrode of first high electron mobility transistor are connected to ohmic electrode through last montant and last sheer pole, the source electrode and the drain electrode of second high electron mobility transistor are connected to ohmic electrode through montant and sheer pole down.
Further, the material of the semiconductor substrate is silicon carbide.
Further, the epitaxial layer is made of gallium nitride.
Furthermore, the material of the high electron mobility transistor is AlGaN/GaN, AlGaAs/GaAs, InGaAs/GaAs or InGaN/GaN.
Further, the first high electron mobility transistor has a size of 12 μm by 10 μm and a thickness of 0.001 to 0.01 μm, and the second high electron mobility transistor has a size of 27 μm by 10 μm and a thickness of 0.001 to 0.01 μm.
Furthermore, the line width of the grid feeder line is 1-3 μm, and the thickness is 0.2-1 μm.
Further, an insulating layer is arranged between the second grid feeder line and the first Schottky electrode.
The invention also provides a method for preparing the terahertz multichannel modulator, which comprises the following steps:
cleaning a substrate, namely respectively placing the SiC substrate in an ultrasonic cleaning machine filled with acetone and ethanol solution, cleaning organic matters on the surface of the SiC substrate, removing metal ions on the surface of the substrate by using hot acid, washing the surface of the substrate by using deionized water and drying the surface of the substrate by using a nitrogen gun;
growing an AlGaN/GaN heterojunction film, and preparing the AlGaN/GaN heterostructure film on the cleaned SiC substrate by using a metal organic compound vapor deposition method;
preparing an active region of the high-electron-mobility transistor, spinning photoresist on a substrate, carrying out photoetching development on the substrate by using a mask to determine the active region of the high-electron-mobility transistor, etching off an AlGaN/GaN film outside the active region of the high-electron-mobility transistor by using an inductively coupled plasma etching method in dry etching, and removing the residual photoresist on the substrate to obtain the active region of the high-electron-mobility transistor;
preparing a source electrode and a drain electrode of the high electron mobility transistor, and depositing composite metal layers of titanium/aluminum/nickel/gold on two sides of an active region in sequence to be used as the source electrode and the drain electrode of the high electron mobility transistor;
ohmic contact is formed between the source electrode and the drain electrode, the source electrode and the drain electrode are placed in an N2 environment, rapid thermal annealing treatment is carried out on the source electrode and the drain electrode, the temperature in an annealing furnace is increased from normal temperature to 890 ℃ within 7s, the temperature is maintained for 20s, then the temperature is rapidly reduced to 25 ℃, and the source electrode and the drain electrode form ohmic contact with the two-dimensional electron gas channel;
preparing a metamaterial structure, sequentially depositing nickel with the thickness of 20nm and gold with the thickness of 150nm on the AlGaN/GaN heterojunction film to form the metamaterial structure, wherein the source electrode and the drain electrode of the high-electron-mobility transistor are covered on two sides of an opening of the metamaterial structure;
the preparation process of the grid feeder line is the same as that of the metamaterial structure.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the invention provides a terahertz multichannel modulator, which is an I-type metamaterial modulator based on a High Electron Mobility Transistor (HEMT). the HEMT with high-speed dynamic characteristics is designed at two openings of a metamaterial structure, the HEMTs at the two openings are respectively controlled by two electrodes, the concentration of two-dimensional electron gas in a channel of the HEMT is adjusted in a mode of externally applying grid voltage, the resonance mode of the metamaterial structure is changed, and further the terahertz waves of multiple frequency bands are regulated and controlled. The modulation depth of the modulator at the center frequency points of 0.12THz, 0.22THz and 0.34THz can reach 97.3 percent, 94.1 percent and 93.5 percent respectively. The modulator adopts a double-opening I-shaped metamaterial structure unit and 2 HEMT designs, namely each modulation array element comprises 2 HEMTs, so that the resonance intensity of the metamaterial structure unit is greatly enhanced, and a foundation is laid for realizing the modulator with high modulation depth and high modulation rate. More importantly, the on-off of the HEMTs at the two openings is controlled by an external voltage signal, the rapid and dynamic regulation and control of the terahertz waves propagated in the free space are realized, the rapid amplitude modulation can be effectively carried out on the terahertz waves of a plurality of frequency points, the multi-channel modulation is realized, and the modulation depth reaches more than 90%.
(2) The terahertz multichannel modulator provided by the invention has strong plasticity, the whole structure of the modulation array element is kept unchanged, the position of the modulation frequency point and the modulation bandwidth can be effectively adjusted by changing the parameters (such as the width of a metal strip) of the metamaterial structural unit, and the terahertz multichannel modulator can be flexibly designed according to the actual application requirement;
(3) the resonance unit of the terahertz multichannel modulator is of a metamaterial structure, is of a two-dimensional plane structure, can be realized through a micro-nano machining process, is mature in machining process and easy to machine, and avoids machining difficulty caused by a complex three-dimensional structure design scheme;
(4) the terahertz multichannel modulator provided by the invention is driven by external voltage, has small size and is easy to integrate, and the designed terahertz modulator is a transmission type terahertz modulator, compared with a reflection type modulator, the terahertz multichannel modulator is simple in operation and convenient to use;
(5) the terahertz multi-channel modulator provided by the invention can work in a free space at normal temperature and normal pressure, and has the advantages of low working voltage, high modulation depth and good practical application prospect.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic structural diagram of a terahertz multichannel modulator according to the present invention;
FIG. 2 is a schematic structural diagram of a modulation array element in a terahertz multichannel modulator according to the present invention;
FIG. 3 is a structural cross-sectional view of a modulation array element in the terahertz multi-channel modulator according to the present invention;
FIG. 4 is a graph of a transmission coefficient of a terahertz multichannel modulator of the present invention;
in the figure: 1. a semiconductor substrate; 2. an epitaxial layer; 3. a Schottky electrode; 4. an ohmic electrode; 5. a high electron mobility transistor; 6. a gate feed line; 7. a source drain feeder line; 8. an insulating layer; 9. a modulation array; 10. modulating array elements; 11. a drain electrode; 12. a source electrode; 13. and a gate.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example one
Referring to fig. 1 to 4, the invention provides a terahertz multichannel modulator, including a semiconductor substrate 1 and an epitaxial layer 2 on the semiconductor substrate 1, where the epitaxial layer 2 is provided with a modulation array 9, a first schottky electrode 3, a second schottky electrode 3, and an ohmic electrode 4, the modulation array 9 is formed by M × N modulation array elements 10 in a periodic arrangement, where M is a longitudinal arrangement period number of the modulation array elements 10, N is a transverse arrangement period number of the modulation array elements 10, M is greater than or equal to 3, N is greater than or equal to 3, the modulation array elements 10 include a structural unit, the structural unit is provided with a first opening and a second opening, and the first opening and the second opening are respectively provided with a first high electron mobility transistor 5 and a second high electron mobility transistor 5; wherein the content of the first and second substances,
the gates 13 of the first high electron mobility transistors 5 of each row of modulation elements 10 are connected to the first schottky electrode 3 by a first gate feed 6 for powering the gates 13 of the first high electron mobility transistors 5; the gates 13 of the second high electron mobility transistors 5 of each row of modulation elements 10 are connected to the second schottky electrode 3 by a second gate feed 6 for supplying power to the gates 13 of the second high electron mobility transistors 5;
the source electrode 12 and the drain electrode 11 of the first high electron mobility transistor 5 of each row of modulation array elements 10 are connected to the ohmic electrode 4 through the first source-drain feeder 7, and are used for supplying power to the source electrode 12 and the drain electrode 11 of the first high electron mobility transistor 5; the source 12 and the drain 11 of the second high electron mobility transistor 5 of each row of modulation elements 10 are connected to the ohmic electrode 4 by a second source-drain feed line 7 for supplying power to the source 12 and the drain 11 of the second high electron mobility transistor 5.
The basic structure of the high electron mobility transistor 5 is a modulation doped heterojunction. The metamaterial structure, the Schottky electrode 3, the ohmic electrode 4, the grid feeder line 6 and the source-drain feeder line 7 can be made of Ti, Ni or Au. In addition, Al, Ag, Cu may be used. In fig. 2, px and py are unit periods, h is a substrate thickness, w is a source-drain feed line 7 width, w1 is a gate feed line 6 width, and g1 and g2 are a first opening and a second opening, respectively;
the invention provides a terahertz multichannel modulator, which is an I-type metamaterial modulator based on a High Electron Mobility Transistor (HEMT) 5, wherein the HEMT with high-speed dynamic characteristics is designed at two openings of a metamaterial structure, the HEMTs at the two openings are respectively controlled by two electrodes, the concentration of 2DEG (two-dimensional electron gas) in a channel of the HEMT is adjusted by adding a grid 13 voltage, the resonance mode of the metamaterial structure is changed, and further the regulation and control of terahertz waves of multiple frequency bands are realized. When no voltage is applied to the modulator, the modulator generates resonance at 0.12THz, and the modulation depth is 97.3%; when a voltage is applied to the HEMT at the first opening g1, the modulator resonates at 0.22THz with a modulation depth of 94.1%, and when a voltage is simultaneously applied to the HEMT at the first opening g1 and the second opening g2, the modulator resonates at 0.34THz with a modulation depth of 93.5%. The modulator adopts a double-opening I-shaped metamaterial structure unit and 2 HEMT designs, namely each modulation array element 10 comprises 2 HEMTs, so that the resonance intensity of the metamaterial structure unit is greatly enhanced, and a foundation is laid for realizing the modulator with high modulation depth and high modulation rate. More importantly, the on-off of the HEMTs at the two openings is controlled by an external voltage signal, the rapid and dynamic regulation and control of the terahertz waves propagated in the free space are realized, the rapid amplitude modulation can be effectively carried out on the terahertz waves of a plurality of frequency points, the multi-channel modulation is realized, and the modulation depth reaches more than 90%.
FIG. 4 is a spectrum of transmission coefficients of the modulator in different open states. In fig. 4, the curves of the triangular symbols represent transmission curves in which the first opening g1 and the second opening g2 are closed, corresponding to the HEMT being not energized; the circled-symbol curve represents the transmission curve for the HEMT under the first opening g1 being energized and the HEMT under the second opening g2 being de-energized, with the first opening g1 open and the second opening g2 closed; the plot of the square symbols represents the transmission curves for two HEMTs powered on with the first opening g1 and the second opening g2 open. When no gate 13 voltage is applied to the HEMT, the modulator resonates at 0.12THz with a transmission coefficient of 0.022, as shown by the black curve with triangles in fig. 4. When a gate 13 voltage is applied to the HEMT at the first opening g1, the modulator resonates at 0.22THz with a transmission coefficient of 0.052 as shown by the rounded black curve in fig. 4. When the gate 13 voltage is applied to the HEMT at the first opening g1 and the second opening g2 simultaneously, the modulator resonates at 0.34THz with a transmission coefficient of 0.060 as shown in fig. 4 with a square black curve. The terahertz waves of three frequency bands can be regulated and controlled by changing the voltage of the grid 13 of the HEMT at the two openings of the modulator. Using the formula MD ═ Toff-Ton)/Toff(ToffIs the transmission coefficient at the time of closing the modulator opening, TonTransmission coefficient for the modulator opening open), the modulation depth of the modulator at 0.12THz, 0.22THz and 0.34THz can be calculated to be 97.3%, 94.1% and 93.5%, respectively.
As a specific implementation manner, an insulating layer 8 is disposed between the second gate feeding line 6 and the first schottky electrode 3, and the insulating layer 8 is benzocyclobutene (BCB).
As a specific embodiment, the structural unit is a metamaterial structural unit. The constitutional unit is I type constitutional unit, the constitutional unit includes horizontal pole, sheer pole and the montant of connecting the sheer pole from top to bottom, first opening and second opening are located the montant, first opening and second opening are cut into montant, well montant and lower montant with the montant, the horizontal pole is first source-drain feeder 7, and the sheer pole is second source-drain feeder 7, first high electron mobility transistor 5's source 12 and drain electrode 11 are connected to ohmic electrode 4 through last montant and last horizontal pole, second high electron mobility transistor 5's source 12 and drain electrode 11 are connected to ohmic electrode 4 through montant and sheer pole down.
In a specific embodiment, the material of the semiconductor substrate 1 is silicon carbide (SiC), the dielectric constant is 9.8, and the thickness h is 100-. Besides, the semiconductor substrate 1 may be made of high-resistance silicon or sapphire. The epitaxial layer 2 is made of gallium nitride. The material of the high electron mobility transistor 5 is AlGaN/GaN, AlGaAs/GaAs, InGaAs/GaAs or InGaN/GaN. The first high electron mobility transistor 5 has a size of 12 μm by 10 μm and a thickness of 0.001 to 0.01 μm, and the second high electron mobility transistor 5 has a size of 27 μm by 10 μm and a thickness of 0.001 to 0.01 μm. The line width of the grid feeder line 6 is 1-3 μm, and the thickness is 0.2-1 μm. The double-opening metamaterial structure unit, the Schottky electrode 3, the ohmic electrode 4, the grid feeder line 6 and the source-drain feeder line 7 can be made of titanium Ti, nickel Ni or gold Au. The line width of the grid feeder line 6 is 2 microns, the line width of the source drain feeder line 7 is 10 microns, and the thickness is 0.2 microns. The period px of the structural unit of the double-opening type I metamaterial is 200 mu m, and py is 210 mu m. The length of the upper transverse rod and the lower transverse rod is 200 μm, the length l1 of the upper vertical rod is 41 μm, the length l2 of the middle vertical rod is 52 μm, the length l3 of the lower vertical rod is 81 μm, the opening size g1 is g2 is 8 μm, and the thickness t is 0.2 μm.
The terahertz multi-channel modulator provided by the invention has strong plasticity, the whole structure of the modulation array element 10 is kept unchanged, the position of a modulation frequency point and the modulation bandwidth can be effectively adjusted by changing the parameters (such as the width of a metal strip) of a metamaterial structural unit, and the terahertz multi-channel modulator can be flexibly designed according to the actual application requirement;
the resonance unit of the terahertz multichannel modulator is of a metamaterial structure, is of a two-dimensional plane structure, can be realized through a micro-nano machining process, is mature in machining process and easy to machine, and avoids machining difficulty caused by a complex three-dimensional structure design scheme;
the terahertz multichannel modulator provided by the invention is driven by external voltage, has small size and is easy to integrate, and the designed terahertz modulator is a transmission type terahertz modulator, compared with a reflection type modulator, the terahertz multichannel modulator is simple in operation and convenient to use;
the terahertz multi-channel modulator provided by the invention can work in a free space at normal temperature and normal pressure, and has the advantages of low working voltage, high modulation depth and good practical application prospect.
Example two
The invention also provides a method for preparing the terahertz multichannel modulator, which comprises the following steps:
cleaning a substrate, namely respectively placing the SiC substrate in an ultrasonic cleaning machine filled with acetone and ethanol solution, cleaning organic matters on the surface of the SiC substrate, removing metal ions on the surface of the substrate by using hot acid, washing the surface of the substrate by using deionized water and drying the surface of the substrate by using a nitrogen gun;
growing an AlGaN/GaN heterojunction film, and preparing the AlGaN/GaN heterostructure film on the cleaned SiC substrate by using a metal organic compound vapor deposition method;
preparing an active region of the high electron mobility transistor 5, spinning photoresist on a substrate, carrying out photoetching development on the substrate by using a mask to determine the active region of the high electron mobility transistor 5, etching off an AlGaN/GaN film outside the active region of the high electron mobility transistor 5 by using an inductively coupled plasma etching method in dry etching, and removing the residual photoresist on the substrate to obtain the active region of the high electron mobility transistor 5;
preparing a source electrode 12 and a drain electrode 11 of the high electron mobility transistor 5, and depositing composite metal layers of titanium/aluminum/nickel/gold on two sides of an active region in sequence to be used as the source electrode 12 and the drain electrode 11 of the high electron mobility transistor 5;
ohmic contact is formed between the source electrode 12 and the drain electrode 11, the source electrode and the drain electrode are placed in an N2 environment, rapid thermal annealing treatment is carried out on the source electrode and the drain electrode, the temperature in an annealing furnace is increased from normal temperature to 890 ℃ within 7s, the temperature is maintained for 20s, then the temperature is rapidly reduced to 25 ℃, and the source electrode 12 and the drain electrode 11 form ohmic contact with the two-dimensional electron gas channel;
preparing a metamaterial structure, sequentially depositing nickel with the thickness of 20nm and gold with the thickness of 150nm on the AlGaN/GaN heterojunction film to form the metamaterial structure, wherein the source electrode 12 and the drain electrode 11 of the high electron mobility transistor 5 are covered on two sides of an opening of the metamaterial structure;
the preparation process of the gate feeder 6 is the same as the preparation process of the metamaterial structure.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A terahertz multichannel modulator is characterized by comprising a semiconductor substrate and an epitaxial layer located on the semiconductor substrate, wherein a modulation array, a first Schottky electrode, a second Schottky electrode and an ohmic electrode are arranged on the epitaxial layer, the modulation array is formed by M multiplied by N modulation array elements in periodic arrangement, M is the longitudinal arrangement period number of the modulation array elements, N is the transverse arrangement period number of the modulation array elements, M is not less than 3, N is not less than 3, the modulation array elements comprise a structural unit, the structural unit is provided with a first opening and a second opening, and the first opening and the second opening are respectively provided with a first high electron mobility transistor and a second high electron mobility transistor; wherein the content of the first and second substances,
the grid electrode of the first high electron mobility transistor of each row of modulation array elements is connected to the first Schottky electrode through a first grid electrode feeder line, and the grid electrode of the second high electron mobility transistor of each row of modulation array elements is connected to the second Schottky electrode through a second grid electrode feeder line;
and the source electrode and the drain electrode of the first high electron mobility transistor of each row of modulation array elements are connected to the ohmic electrode through a first source drain feeder line, and the source electrode and the drain electrode of the second high electron mobility transistor of each row of modulation array elements are connected to the ohmic electrode through a second source drain feeder line.
2. The terahertz multichannel modulator of claim 1, wherein the structural unit is a metamaterial structural unit.
3. The terahertz multichannel modulator of claim 1 or 2, wherein the structural unit is an I-type structural unit, the structural unit includes an upper cross bar, a lower cross bar, and a vertical bar connecting the upper and lower cross bars, the first opening and the second opening are located on the vertical bar, the first opening and the second opening cut the vertical bar into an upper vertical bar, a middle vertical bar, and a lower vertical bar, the upper cross bar is a first source-drain feeder line, the lower cross bar is a second source-drain feeder line, a source and a drain of the first hemt are connected to the ohmic electrode through the upper vertical bar and the upper cross bar, and a source and a drain of the second hemt are connected to the ohmic electrode through the lower vertical bar and the lower cross bar.
4. The terahertz multichannel modulator of claim 1, wherein the material of the semiconductor substrate is silicon carbide.
5. The terahertz multichannel modulator of claim 1, wherein the material of the epitaxial layer is gallium nitride.
6. The terahertz multichannel modulator of claim 1, wherein the material of the high electron mobility transistor is AlGaN/GaN, AlGaAs/GaAs, InGaAs/GaAs, or InGaN/GaN.
7. The terahertz multi-channel modulator of claim 1, wherein the first high electron mobility transistor is 12 μ ι η by 10 μ ι η in size and 0.001-0.01 μ ι η thick, and the second high electron mobility transistor is 27 μ ι η by 10 μ ι η in size and 0.001-0.01 μ ι η thick.
8. The terahertz multichannel modulator of claim 1, wherein the gate feed line has a line width of 1-3 μ ι η and a thickness of 0.2-1 μ ι η.
9. The terahertz multichannel modulator of claim 1, wherein an insulating layer is disposed between the second gate feed line and the first schottky electrode.
10. A method of preparing the terahertz multichannel modulator of claim 1, comprising:
cleaning a substrate, namely respectively placing the SiC substrate in an ultrasonic cleaning machine filled with acetone and ethanol solution, cleaning organic matters on the surface of the SiC substrate, removing metal ions on the surface of the substrate by using hot acid, washing the surface of the substrate by using deionized water and drying the surface of the substrate by using a nitrogen gun;
growing an AlGaN/GaN heterojunction film, and preparing the AlGaN/GaN heterostructure film on the cleaned SiC substrate by using a metal organic compound vapor deposition method;
preparing an active region of the high-electron-mobility transistor, spinning photoresist on a substrate, carrying out photoetching development on the substrate by using a mask to determine the active region of the high-electron-mobility transistor, etching off an AlGaN/GaN film outside the active region of the high-electron-mobility transistor by using an inductively coupled plasma etching method in dry etching, and removing the residual photoresist on the substrate to obtain the active region of the high-electron-mobility transistor;
preparing a source electrode and a drain electrode of the high electron mobility transistor, and depositing composite metal layers of titanium/aluminum/nickel/gold on two sides of an active region in sequence to be used as the source electrode and the drain electrode of the high electron mobility transistor;
ohmic contact is formed between the source electrode and the drain electrode, the source electrode and the drain electrode are placed in an N2 environment, rapid thermal annealing treatment is carried out on the source electrode and the drain electrode, the temperature in an annealing furnace is increased from normal temperature to 890 ℃ within 7s, the temperature is maintained for 20s, then the temperature is rapidly reduced to 25 ℃, and the source electrode and the drain electrode form ohmic contact with the two-dimensional electron gas channel;
preparing a metamaterial structure, depositing nickel with the thickness of 20nm and gold with the thickness of 150nm on the A1GaN/GaN heterojunction film in sequence to form the metamaterial structure, wherein the two sides of an opening of the metamaterial structure cover a source electrode and a drain electrode of the high-electron-mobility transistor;
the preparation process of the grid feeder line is the same as that of the metamaterial structure.
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| CN115084842B (en) * | 2022-06-29 | 2024-05-14 | 四川太赫兹通信有限公司 | Terahertz is automatically controlled coding antenna unit and terahertz is automatically controlled coding antenna now |
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