KR101626804B1 - A transceiver without bias voltage acting in terahertz frequency - Google Patents

Abstract

The present invention is directed to a voltage-free transceiver operating in the terahertz (THz) band.
A voltage-free transceiver operating in the THz band according to the present invention comprises: a substrate; A transmitter (Tx) located on the substrate and transmitting THz waves and not using a bias voltage; And a receiver (Rx) located at a predetermined distance from the Tx and detecting a THz wave, wherein the Tx is constituted by a metal line having a constant thickness and a line width, and the Rx is a second active layer ; And a photoconductive antenna positioned on the second active layer.
According to the above-described configuration, the voltage-free transceiver operating in the THz band according to the present invention does not use a bias voltage, so that the signal-to-noise ratio is remarkably improved, the laser pulse having a low peak power can be used, Even when applied to equipment, it can be used safely.

Description

TECHNICAL FIELD [0001] The present invention relates to a voltage transceiver operating in a terahertz band,

The present invention relates to a voltage-free transceiver operating in the terahertz (THz) band, and more particularly to a voltage-free transceiver operating in a terahertz (THz) band by forming a THz wave transmitter (Tx) and a receiver To a voltage-free transceiver operating in a THz band capable of transmitting and detecting a THz wave within a frequency band.

The terahertz (THz) wave is an electromagnetic wave with a frequency in the range of 100GHz to 10THz between infrared and microwave. Recently, it has been recognized as a future radio resource by the development of advanced technology, Information Technology), BT (Bio Technology), and so on.

In particular, the THz wave propagates like a visible ray and transmits a variety of materials such as radio waves, so it is used not only for basic science such as physics, chemistry, biology, medicine, but also for detection of counterfeit bills, drugs, explosives, biochemical weapons, It is expected to be widely used in the fields of general industry, defense, security, etc. because it is possible to inspect structures non-destructively. Also, in the field of information communication, it is expected that THz technology will be widely used in 40Gbit / s wireless communication, high-speed data processing, and inter-satellite communication.

Such a THz wave can be divided into a continuous type and a pulse type according to the generation method. The pulse type THz wave is a method of generating a THz wave by irradiating a special semiconductor or optical crystal with a femtosecond (fs: ^10-15 seconds) pulse laser.

Fig. 1 is a view for explaining a method of generating a pulsed THz wave by irradiating a fs pulse laser to a photoconductive antenna.

1, the photoconductive antenna 100 includes a photoconductive epilayer or a hetero multiple epilayer formed on an insulator or a semi-insulating (SI) semiconductor substrate 110, (120) and a metal parallel transmission line (130) having a central protruding portion formed on the photoconductive thin film (120). Here, the portion projecting to the central region of the metal parallel transmission line 130 functions as a dipole antenna.

When the metal parallel transmission line 130 is intermittently excited using laser pulse light having a time width of 100 fs or less in a state of applying a bias voltage V _b of an appropriate size, A carrier of electrons and holes is generated and a current flows instantaneously through the metal parallel transmission line 130 and a THz wave proportional to the time differential value of the current is generated.

This is emitted to the thin film substrate THz wave 110 generated in the 120 direction, and this pulse width of the THz-wave radiation, such as the 1 picosecond (picosecond, ps: 10 ^-12 second) or less, or more general-purpose pulse laser 30fs The spectrum obtained by the Fourier transform has a wide band from zero to several THz frequencies.

In order to generate a strong THz wave on the back surface of the substrate 110, the fs laser excitation light is focused on the photoconductive antenna 130 through a focusing lens, and a hemispherical lens (hemi- collimation through a spherical lens.

However, in the conventional THz wave transmitting / receiving apparatus, since a THz wave can be generated or detected by an individual element in which a transmitter (Tx) and a receiver (Rx) equipped with respective photoconductive antennas are separated, And the size and application of the apparatus have been limited. An attempt has been made to integrate the Tx and Rx discrete elements on a single chip in order to compensate for this restriction, a significant increase in the methods conventional attempt has noise by the bias voltage (Fig. 1, V _b) for applying the THz generation (noise) And the signal-to-noise ratio is very low.

On the other hand, there is a THz transceiver that transmits and detects a THz wave by using a single device without using a bias voltage. However, in order to generate a THz wave with the THz wave transceiver, the repetition rate is several kilohertz (kHz) There is a problem in that a laser pulse having a high peak power is required to be used.

In addition, when such a conventional THz wave transmitting / receiving device is mounted on a medical device to be used for a human body, a safety problem due to voltage application may arise. In addition, when using a high-power pulse laser, There is a problem that can result.

Korean Registered Patent No. 10-1145778 (registered on May 07, 2012) Korean Patent Laid-Open No. 10-2009-0056764 (published on June 03, 2009)

The present invention is to provide a voltage-free transceiver operating in the THz band capable of transmitting and detecting THz waves in a single chip by integrating a THz transmitter (Tx) and a receiver (Rx) on a single chip .

It is another object of the present invention to provide a voltage-free transceiver that operates in the THz band, in which a bias voltage is not used, so that the signal-to-noise ratio is remarkably improved and a laser pulse having a low peak power can be used.

The present invention also provides a voltage-free transceiver that operates in the THz band, which can be used safely even when applied to medical equipment that needs to be applied to a human body.

The various problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

A voltage-free transceiver operating in the THz band according to the present invention comprises: a substrate; A transmitter (Tx) located on the substrate and transmitting a terahertz (THz) wave and not using a bias voltage; And a receiver (Rx) located at a predetermined distance from the Tx and detecting a THz wave, wherein the Tx is constituted by a metal line having a constant thickness and a line width, and the Rx is a second active layer active layer); And a photoconductive antenna positioned on the second active layer.

The receiver Rx may be formed of a heterogeneous thin film or a heteroepitaxial thin film including a multi quantum well (MQW layer).

The active layer may be composed of a first active layer grown at a normal temperature on a single chip and a second active layer of a low temperature growth (LTG).

Tx is a thin film of InGaAs grown at a normal temperature formed on the substrate; And a heterogeneously stacked thin film including MQWs formed on the substrate.

The upper and the side surfaces of the heteroepitaxial thin film may be provided with metal pads formed of a single-layer or multi-layer conductive material.

A first buffer layer or a second buffer layer may be further formed on the substrate.

The photoconductive antenna may be formed of a single-layered or multi-layered conductive material on the upper and side surfaces of the second active layer of Rx.

A voltage-free transceiver operating in the THz band according to the present invention can transmit and detect THz waves in a single chip by integrating a THz wave transmitter (Tx) and a receiver (Rx) on a single substrate.

Further, the voltage-free transceiver operating in the THz band according to the present invention does not use a bias voltage, so that the signal-to-noise ratio is remarkably improved and a laser pulse having a low peak power can be used.

Further, the voltage-free transceiver operating in the THz band according to the present invention can be safely used even when applied to a medical device which is intended for a human body.

It will be appreciated that embodiments of the technical idea of the present invention can provide various effects not specifically mentioned.

1 is a view for explaining a method of generating a pulsed THz wave by irradiating a fs laser to a photoconductive antenna in the prior art.
2 is a cross-sectional view of a voltage-free transceiver operating in the THz band in accordance with the present invention.
3 is a top view of a voltage-free transceiver operating in the THz band in accordance with the present invention.
4 is a cross-sectional view of a receiver Rx in a voltage-free transceiver operating in the THz band in accordance with the present invention.
5 to 7 are views for explaining a method of manufacturing a voltage-free transceiver operating in the THz band according to the present invention.
FIG. 8 is a graph showing a result of detection of a THz wave by a receiver Rx of a voltage-free transceiver operating in the THz band according to the present invention.
9 is a graph showing the relationship between a typical noise signal and a signal current (peak-to-peak) according to a laser output when a THz wave is generated by a photo-diode (pD) effect in a voltage- current.
10 is a schematic diagram for illustrating the pD effect in a voltage-free transceiver operating in the THz band according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity.

Terms such as top, bottom, top, bottom, or top, bottom, etc. are used to distinguish relative positions in components. For example, in the case of naming the upper part of the drawing as upper part and the lower part as lower part in the drawings for convenience, the upper part may be named lower part and the lower part may be named upper part without departing from the scope of right of the present invention .

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be construed as ideal or overly formal in meaning unless explicitly defined in the present application Do not.

Hereinafter, a preferred embodiment of a voltage-free transceiver operating in the THz band according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view of a voltage-free transceiver operating in the THz band according to the present invention, FIG. 3 is a plan view showing a voltage-free transceiver operating in the THz band according to the present invention, 5 is a view for explaining a method of manufacturing a voltage-free transceiver operating in a THz band according to the present invention, and Fig. 8 is a view for explaining a method of manufacturing a THz band according to the present invention, FIG. 9 is a graph showing a result of detection of a THz wave by a receiver Rx of a voltage-free transceiver operating in a band. FIG. 9 is a graph showing a photo-Dember (pD) in a voltage-free transceiver operating in the THz band according to the present invention. FIG. 10 is a graph showing a typical noise signal and a signal current (peak-to-peak current) according to a laser output when the THz wave is generated by the effect of the present invention. It is a schematic diagram for explaining an operation in the no-voltage pD effect transceiver.

The voltage-free transceiver operating in the THz band according to the present invention is configured to transmit and detect a THz wave by integrating a THz transmitter (Tx) 400 and a receiver (Rx) 500 on a single substrate 200 , It is a device that can transmit and detect THz waves in a single chip rather than an individual device. 2 to 10, a voltage-free transceiver operating in the THz band according to the present invention includes a substrate 200, a Tx 400 formed on the substrate 200, and an Rx 500.

The substrate 200 is a substrate for forming the Tx 400 and the Rx 500 in a subsequent process, and may be a semi-insulating semiconductor or an insulator. The substrate 200 may be an insulator substrate capable of forming SI-GaAs or SI-InP, and other Tx or Rx upper layer structures.

In the voltage-free transceiver operating in the THz band according to the present invention, a first buffer layer 300a may be further formed on the substrate 200. [ The first buffer layer 300a may be formed of InP or indium gallium arsenide (InGaAs). For example, the first buffer layer 300a serves as a buffer to easily grow an InGaAs thin film or the like, which is an active layer formed in a subsequent process, on the substrate 200.

The Tx 400 may be disposed on the substrate 200 or the first active layer 410 and may be provided to transmit a THz wave. The Tx 400 may be formed of a metal line having a predetermined thickness and line width, and may be formed of gold (Au), titanium (Ti), or a lamination thereof.

In the present invention, the line width of the metal line of the Tx 400 (that is, the line width of the Tx 400 with respect to the direction parallel to the first active layer 410) may be 10 to 300 탆. It is preferable that the thickness of the Tx 400 (i.e., the thickness of the Tx 400 with respect to the direction perpendicular to the first active layer 410) is 100 nm to 500 nm for Au and 10 nm to 50 nm for Ti .

The Tx 400 generates a THz wave using a photo-demodulator (pD) effect. The first active layer 410 may be formed of an InGaAs-based homo-thin film or a hetero-laminated thin film including the same, for example, an InGaAs / InAlAs multi- Quantum well (MQW) structures.

Metal pads (not shown) may be formed on the top and side surfaces of the first active layer 410. The metal pad may be formed of a single layer or a multilayer conductive material, and the conductive material may be formed of the same material as the metal line of Tx.

In the non-voltage transceiver operating in the THz band according to the present invention, the transmitter 400 generates a THz wave using the pD effect. Referring to FIG. 10, the pD effect is generated by applying a laser pulse (-) and holes (+) are generated when the electron _beam is _{irradiated on the} surface of the _substrate , and a dipole moment ( P _Dember ) as shown in FIG. 10 410) is formed in a plane perpendicular to the thin film (410) plane and is a THz wave generator in parallel, when irradiating the laser pulse on one side of the metal pad, as shown in FIG. 10 (b) P _Dember the thin film (410) plane and And a THz wave is generated in a direction perpendicular to the thin film 410 surface.

The Rx 500 is located on the second active layer 510 and is spaced apart from the Tx 400 by a predetermined distance. The Rx 500 detects a THz wave transmitted to a voltage-free transceiver operating in the THz band according to the present invention. .

For example, the Tx 400 and the Rx 500 may be configured such that the horizontal distance is 10 占 퐉 to 500 占 퐉 apart. The Rx 500 is located on the second active layer 510 formed on the first active layer 410.

The second active layer 510 may be composed of a low-temperature grown (LTG) InGaAs type homo-thin film or a heteroepitaxial thin film, and the first active layer 410 and the second active layer 510 may include a 2 buffer layer 300b can be inserted.

The photoconductive antenna 520 may be provided to detect a THz wave transmitted to a voltage-free transceiver operating in the THz band according to the present invention. A metal pad (not shown) may be formed on the upper and side surfaces of the second active layer 510 of the photoconductive antenna 520. The metal pad may be formed of a conductive material of a single layer or a laminate, and the conductive material may be formed of the same material as Rx.

The photoconductive antenna 520 may include a metal parallel transmission line 524 having a central protrusion 526 and an electrode pad 522 formed symmetrically at both ends of the metal parallel transmission line 524.

Here, the protrusion 526 formed in the central region of the metal parallel transmission line 524 serves as a dipole antenna. The electrode pad 522 formed at both ends of the metal parallel transmission line 524 may be connected to a wire for electrical connection with an external measuring instrument.

Hereinafter, a method of manufacturing a voltage-free transceiver operating in a THz band according to the present invention will be described in detail with reference to the accompanying drawings.

First, a substrate 200 is provided as shown in FIG. The substrate 200 may be an insulator or a semi-insulating semiconductor substrate 200, and may be formed of an insulating material such as SI-GaAs or SI-InP or sapphire.

Next, a first buffer layer 300a may be formed on the substrate 200. Referring to FIG. The first buffer layer 300a may be formed of an InGaAs-based material.

A first active layer 410 may be formed on the first buffer layer 300a and the first active layer 410 may be formed on the first buffer layer 300a using an InGaAs- (For example, InGaAs / InAlAs MQW). A second buffer layer 300b may be formed on the first active layer 410 to electrically isolate the second active layer 510 from the second active layer.

A second active layer 510 may be formed on the second buffer layer 300b and the second active layer 510 may be formed on the second buffer layer 300b by using a low temperature growth (LTG) Thin film or a heterostructured thin film (for example, LTG-InGaAs / InAlAs MQW).

The second active layer 510 and the second buffer layer 300b may be partially removed to expose the first active layer 410 at the portion where the Tx 400 is formed. For example, the second buffer layer 300b and the second active layer 510 may be removed by photolithography using chemical etching or dry etching.

Next, a Tx 400 may be formed on the exposed first active layer 410, and a photoconductive antenna 520 functioning as an Rx 500 may be formed on the second active layer 510. The Tx 400 may be formed of a metal line having a constant thickness and line width, and may be formed of a metal such as Au or Ti. The photoconductive antenna 520 is formed to be spaced apart from the Tx 400 by a predetermined distance and a first active layer 410 and a first buffer layer 300a are formed between the Tx 400 and the Rx 500, Can be removed.

The Tx 400 and the photoconductive antenna 520 may be configured to have a predetermined shape. For example, the Tx 400 and the photoconductive antenna 520 may include metal lines of the Tx 400, electrode pads 522 ), The metal parallel transmission line 524 and the central projection 526 can be patterned by standard lithography methods.

The non-voltage transceiver finally manufactured in the above procedure is shown in FIGS. 6 and 7. FIG. The thicknesses of the first and second buffer layers 300a and 300b and the first and second active layers 410 and 510 are very thin in comparison with the substrate 200 in the actual specifications, As shown in Fig.

Experimental Example  One

8 illustrates a second active layer 510 forming a receiver (Rx) 500 in a voltage-free transceiver operating in the THz band according to the present invention as a low temperature grown (LTG) InGaAs thin film and an InGaAs / InAlAs-MQW layer And THz wave using the deposited Rx (500).

Referring to FIG. 8, it can be seen that the LTG-MQW can detect a signal about 10 times larger than that of the LTG-MQW.

Experimental Example  2

9 is a graph showing a noise change after generating a THz wave by a p-D effect with a voltage-free transceiver operating in the THz band according to the present invention.

Referring to FIG. 9, it can be seen that even when the output of the laser pulse is increased in order to generate a strong THz wave, the intensity of the noise hardly changes.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that one embodiment described above is illustrative in all aspects and not restrictive.

200; Substrate 300a; The first buffer layer
300b; A second buffer layer 400; transmitter
410; First active layer 510 Second active layer
520; A photoconductive antenna 522; Electrode pad
524; Metal parallel transmission line 526; Center protrusion

Claims (7)

Board;
A transmitter (Tx) located on the substrate and generating and transmitting a terahertz (THz) wave and not using a bias voltage; And
And a receiver (Rx) positioned on the substrate and spaced apart from the Tx by a predetermined distance to detect a THz wave,
In the above Tx,
A first active layer located on the substrate; And
A metal line having a constant thickness and line width,
The Rx,
A second active layer located on the substrate; And
And a photoconductive antenna positioned on the second active layer.
Single-chip voltage-free transceiver operating in the THz band.
The method according to claim 1,
Wherein the receiver (Rx) is formed of a homogeneous thin film or a heterostructured thin film comprising MQW.
The method according to claim 1,
Wherein the active layer is composed of a first active layer grown at a normal temperature on a single chip and a second active layer of a low temperature growth (LTG) layer.
The method according to claim 1,
In the above Tx,
A thin film of InGaAs grown on the substrate at a normal temperature; And
Lt; RTI ID = 0.0 > (MQW) < / RTI > formed on the substrate.
5. The method of claim 4,
Chip transceiver operating in the THz band, characterized in that a metal pad is formed on the top and sides of the hetero-laminated thin film, the pad being formed of a single layer or multiple layers of conductive material.
delete 3. The method of claim 2,
Wherein the photoconductive antenna is provided with a metal pad which is formed of a single layer or a multi-layer conductive material on the upper portion and the side surface of the heteroepitaxial thin film including the MQW.

Images