JP7284585B2 - terahertz element - Google Patents

Description

The present disclosure relates to terahertz devices.

2. Description of the Related Art In recent years, miniaturization of electronic devices such as transistors has progressed, and the size of electronic devices has become nano-sized, so a phenomenon called a quantum effect has been observed. Developments are underway with the aim of realizing ultrahigh-speed devices and devices with new functions that utilize this quantum effect. In such an environment, attempts are being made to perform high-capacity communication, information processing, imaging, measurement, etc., using a frequency region called the terahertz band (0.1 THz to 10 THz frequency band). . This frequency range has the characteristics of both light and radio waves, and if a device that operates in this frequency band is realized, in addition to the aforementioned imaging, large-capacity communication and information processing, physical properties, astronomy, biology, etc. It can be used for many purposes such as measurement in various fields of

Patent Literature 1 discloses a measuring device using terahertz waves. The measuring device described in Patent Document 1 includes generation means for generating terahertz waves and detection means for detecting terahertz waves. The generating means has a terahertz wave generating element, and the detecting means has a terahertz wave detecting element. According to this measuring device, the terahertz wave generated by the terahertz wave generation element is irradiated onto the measurement object, and the terahertz wave reflected or transmitted by the measurement object is detected by the terahertz wave detection element. Measurements (eg, imaging, characterization, etc.) are performed. In order to improve the measurement accuracy of such a measuring device, it is required to improve the detection accuracy of terahertz waves by, for example, a terahertz wave detection element.

JP 2015-87155 A

A main object of the present disclosure is to provide a terahertz element with improved detection accuracy of terahertz waves.

A terahertz device of the present disclosure includes a detection unit that detects terahertz waves, and the detection unit includes a semiconductor substrate, a first semiconductor layer arranged on the semiconductor substrate, and a semiconductor layer on the first semiconductor layer. a first active device comprising a first quantum well layer disposed thereon and a second semiconductor layer disposed over said first quantum well layer; and a first semiconductor formed on said semiconductor substrate and said first active device a first electrode connected to a layer; and a second electrode formed on the semiconductor substrate and connected to the second semiconductor layer, the second electrode being connected to the It is electrically connected to the first electrode only through a conduction path through the first quantum well layer, the detection unit has a nonlinear current-voltage characteristic, and the current-voltage characteristic is such that the first When a forward voltage is applied to the active element, the larger the voltage value of the forward voltage, the larger the current value flowing through the first active element.

According to the terahertz element of the present disclosure, detection accuracy of terahertz waves can be improved.

1 is a schematic diagram of a planar pattern of a terahertz element according to a first embodiment; FIG. FIG. 2 is an enlarged view of a main portion of a region II of FIG. 1; FIG. 3 is a schematic cross-sectional view of the terahertz element according to the first embodiment, which is a cross-section taken along line III-III of FIG. 2; FIG. 4 is an enlarged cross-sectional view of a part of FIG. 3 ; FIG. 4 is a diagram showing current-voltage characteristics of a detection unit; FIG. 10 is a schematic diagram of a planar pattern of a terahertz element according to a second embodiment; 3 is a schematic diagram of a cross section of an oscillator; FIG. FIG. 8 is an enlarged cross-sectional view of a part of FIG. 7; FIG. 10 is a schematic diagram of a planar pattern of a terahertz element according to a third embodiment; FIG. 11 is an enlarged cross-sectional view of a main part of a terahertz device according to a third embodiment;

Preferred embodiments of the terahertz device of the present disclosure will be described below with reference to the drawings. It should be noted that the terms "first", "second", etc. in this disclosure are merely used as labels and are not necessarily intended to impose a permutation on those objects.

In the present disclosure, unless otherwise specified, the terms “a certain entity A is formed on a certain entity B” and “a certain entity A is formed on a certain entity B” mean “a certain entity A is formed on a certain entity B”. It includes "being directly formed in entity B" and "being formed in entity B while another entity is interposed between entity A and entity B". Similarly, unless otherwise specified, ``an entity A is placed on an entity B'' and ``an entity A is located on an entity B'' mean ``an entity A is located on an entity B.'' It includes "directly placed on B" and "some entity A is placed on an entity B while another entity is interposed between an entity A and an entity B." Similarly, unless otherwise specified, ``an object A is located on an object B'' means ``an object A is adjacent to an object B and an object A is positioned on an object B. and "the thing A is positioned on the thing B while another thing is interposed between the thing A and the thing B". Similarly, unless otherwise specified, ``an object A is laminated on an object B'' and ``an object A is laminated on an object B'' means ``an object A is laminated on an object B.'' It includes "directly laminated on B" and "a thing A is laminated on a certain thing B while another thing is interposed between the thing A and the thing B".

1 to 4 show a terahertz device according to a first embodiment of the present disclosure. The terahertz element A1 of the first embodiment includes a detection section 1 that detects terahertz waves. The detection section 1 includes a semiconductor substrate 11 , an active element 12 , a first electrode 13 , a second electrode 14 and an insulating layer 15 .

FIG. 1 is an example of a schematic diagram of a planar pattern of the terahertz element A1. FIG. 2 is an enlarged view of a main part of area II in FIG. FIG. 3 is a cross section taken along line III-III in FIG. 2 and is an example of a schematic cross-sectional view of the terahertz element A1. FIG. 4 is an enlarged cross-sectional view of a part of FIG. 3 . 1, 2 and 4, the insulating layer 15 is omitted. Note that the configuration of the terahertz element A1 shown in FIGS. 1 to 4 is an example.

The semiconductor substrate 11 is a semi-insulating substrate made of a semiconductor material. A constituent material of the semiconductor substrate 11 is, for example, InP (indium phosphide).

Active element 12 is typically a resonant tunneling diode (RTD). The active element 12 may be composed of a diode or a transistor other than the RTD. Examples of such diodes and transistors include TUNNETT (Tunnel Transit Time) diodes, IMPATT (Impatt: Impact Ionization Avalanche Transit Time) diodes, GaAs-based field effect transistors (FETs), and GaN-based FETs. , High Electron Mobility Transistor (HEMT), or Heterojunction Bipolar Transistor (HBT). Active elements 12 are formed on a semiconductor substrate 11 . Active element 12 is electrically connected to first electrode 13 and second electrode 14 .

An example for realizing the active element 12 will be described with reference to FIG. The active element 12 is formed by laminating a plurality of semiconductor layers. As shown in FIG. 4, an InGaAs layer 121a is arranged on the semiconductor substrate 11 . The InGaAs layer 121a is heavily doped with an n-type impurity. An InGaAs layer 122a is arranged on the InGaAs layer 121a. The InGaAs layer 122a is doped with an n-type impurity. An InGaAs layer 123a is arranged on the InGaAs layer 122a. The InGaAs layer 123a is not doped with impurities. An AlAs layer 124a is arranged on the InGaAs layer 123a, an InGaAs layer 125 is arranged on the AlAs layer 124a, and an AlAs layer 124b is arranged on the InGaAs layer 125. FIG. An InGaAs layer 123b is arranged on the AlAs layer 124b. The InGaAs layer 123b is not doped with impurities. An InGaAs layer 122b is arranged on the InGaAs layer 123b. The InGaAs layer 122b is doped with an n-type impurity. An InGaAs layer 121b is arranged on the InGaAs layer 122b. The InGaAs layer 121b is heavily doped with n-type impurities. A second electrode 14 is arranged on the InGaAs layer 121b.

The AlAs layer 124a, the InGaAs layer 125 and the AlAs layer 124b constitute the RTD portion of the active element 12. FIG. The InGaAs layer 125 is a quantum well layer, and the AlAs layers 124a and 124b are tunnel barrier layers, respectively. The InGaAs layer 125 is relatively thicker than the AlAs layers 124a, 124b. The indium content in the InGaAs layer 125 is relatively higher than the indium content in the other layers containing indium (the InGaAs layers 121a to 123a and 121b to 123b).

Although not shown, unlike FIG. 4, an InGaAs layer heavily doped with n-type impurities may be interposed between the InGaAs layer 121b and the second electrode . This can improve the contact between the second electrode 14 and the InGaAs layer 121b. An InGaAs layer not doped with impurities may be interposed between the InGaAs layer 121 a and the semiconductor substrate 11 .

Although not shown, unlike FIGS. 3 and 4, a back reflector metal layer may be disposed on the surface of the semiconductor substrate 11 opposite to the surface on which the active elements 12 are disposed.

In this embodiment, the active element 12 is an example of the "first active element" described in the claims. The InGaAs layer 121a, the InGaAs layer 125 and the InGaAs layer 121b are examples of the "first semiconductor layer", the "first quantum well layer" and the "second semiconductor layer" described in the claims.

The first electrode 13 and the second electrode 14 are terminals of the terahertz element A1. The first electrode 13 is formed on the semiconductor substrate 11 and partly disposed on the InGaAs layer 121a. The second electrode 14 is formed on the semiconductor substrate 11 and partly arranged on the InGaAs layer 121b. As shown in FIG. 3, the second electrode 14 is not in contact with the InGaAs layer 121a, and the insulating layer 15 is interposed between it and the InGaAs layer 121a. The first electrode 13 and the second electrode 14 are arranged apart from each other.

The first electrode 13 and the second electrode 14 each have a metal laminate structure. The laminated structure of each of first electrode 13 and second electrode 14 is, for example, a structure in which Au (gold), Pd (palladium) and Ti (titanium) are laminated. Alternatively, the laminated structure of each of the first electrode 13 and the second electrode 14 is a structure in which Au and Ti are laminated. Both the first electrode 13 and the second electrode 14 can be formed by a vacuum deposition method, a sputtering method, or the like.

The first electrode 13 includes an antenna section 131 , a feeder section 132 and a pad electrode section 133 . The second electrode 14 includes an antenna portion 141 , a feeder portion 142 and a pad electrode portion 143 . The terahertz element A1 has an integrated antenna structure composed of the antenna section 131 and the antenna section 141 . In the example shown in FIG. 1, the antenna section 131 and the antenna section 141 constitute a dipole antenna. The antenna formed by the antenna section 131 and the antenna section 141 is not limited to a dipole antenna, and may be another antenna such as a slot antenna, a bowtie antenna, or a ring antenna. Feeder section 132 is connected to antenna section 131 (dipole antenna) and pad electrode section 133 , and feeder section 142 is connected to antenna section 141 (dipole antenna) and pad electrode section 143 . Note that the first electrode 13 may not include the feeder portion 132 and the pad electrode portion 133 . Also, the second electrode 14 may not include the feeder portion 142 and the pad electrode portion 143 .

The insulating layer 15 is formed of, for example, a SiO ₂ film, a Si ₃ N ₄ film, a SiON film, a HfO ₂ film, an Al ₂ O ₃ film, or a multilayer film thereof. The insulating layer 15 covers the side walls of the laminated structure (active element 12) shown in FIG. The insulating layer 15 is interposed between the InGaAs layer 121a and the second electrode 14 to insulate them. The insulating layer 15 can be formed by a chemical vapor deposition (CVD) method, a sputtering method, or the like.

FIG. 5 shows the current-voltage characteristics of the detector 1. FIG. In FIG. 5, the horizontal axis represents the voltage VRTD applied between the first electrode 13 and the second electrode 14 when the forward voltage is applied to the active element 12, and the vertical _axis represents , the current I _RTD flowing between the first electrode 13 and the second electrode 14 when a forward voltage is applied to the active element 12 . In this embodiment, when a forward voltage is applied to the active element 12, the first electrode 13 is on the high potential side and the second electrode 14 is on the low potential side. Conversely, when a forward voltage is applied to the active element 12, the second electrode 14 may be on the high potential side and the first electrode 13 may be on the low potential side.

In FIG. 5, a characteristic line L1 (indicated by a solid line) indicates current-voltage characteristics of the detection section 1 when a forward voltage is applied to the active element 12. In FIG. As indicated by the characteristic line L1, the current-voltage characteristics of the detector 1 have the following characteristics when a forward voltage is applied to the active element 12. FIG. It is non-linear. Also, the larger the value of the voltage V _RTD applied to the active element 12, the larger the value of the current I _RTD flowing through the active element 12. FIG. That is, the value of current I _RTD monotonously increases as the value of voltage V _RTD increases. Furthermore, there is no negative resistance region. The negative resistance region is a region in which the value of current I _RTD decreases as the value of voltage V _RTD increases. The current-voltage characteristics of the detection unit 1 when a reverse voltage is applied to the active element 12 may or may not have a negative resistance region.

The characteristic line L1 includes a first curved portion L11 and a second curved portion L12. In the first curved portion L11, the larger the value of the forward voltage _VRTD , the smaller the differential coefficient of the characteristic line L1. In the second curve portion L12, the larger the value of the forward voltage _VRTD , the larger the differential coefficient of the characteristic line L1. In the current-voltage characteristics of the detection section 1, there is a boundary point P1 where the first curve portion L11 and the second curve portion L12 are switched. The voltage value at the second curved portion L12 is greater than the voltage value at the first curved portion L11. The first curved portion L11 and the second curved portion L12 are continuous via a boundary point P1. Therefore, in the characteristic line L1 of FIG. 5, in the state where the forward voltage is applied to the active element 12, the boundary point P1 becomes the first curved portion L11 when the value of the voltage V _RTD is small. When the value of the voltage V _RTD is in a large range, the second curve portion L12 is formed. In other words, if the value of the voltage V _RTD at the boundary point P1 is V1, the current-voltage characteristic shown in the first curved portion L11 is obtained when the forward voltage is 0 or more and less than V1, and when the forward voltage is greater than V1. The current-voltage characteristics are shown in the second curve portion L12.

Next, the effects of the terahertz element A1 according to the first embodiment will be described.

The terahertz element A1 includes the detection section 1 having the current-voltage characteristic indicated by the characteristic line L1 in FIG. The current-voltage characteristic of the detection unit 1 is nonlinear, and when a forward voltage is applied to the active element 12, the current value increases as the voltage value increases. In a terahertz element that is different from the present disclosure and has a current-voltage characteristic indicated by the characteristic line L2 in FIG. , which oscillates terahertz waves. It should be noted that the larger the ΔV and ΔI (see FIG. 5) in the negative resistance region, the more advantageous the oscillation of the terahertz wave. However, when operated in the negative resistance region, parasitic oscillation occurs between external circuits. This parasitic oscillation causes noise when detecting terahertz waves, and may destabilize the detection operation. On the other hand, in the current-voltage characteristics of the terahertz element A1, when a forward voltage is applied to the active element 12, the current value increases as the voltage value increases, so there is no negative resistance region as described above. Therefore, the aforementioned parasitic oscillation can be suppressed. Therefore, the terahertz element A1 can prevent the detection operation of the terahertz wave from becoming unstable, thereby improving the detection accuracy of the terahertz wave.

According to the terahertz element A1, the first electrode 13 and the second electrode 14 are electrically connected only through the conduction path through the InGaAs layer 125 (quantum well layer) of the active element 12. FIG. The inventors of the present application have found that the above-described terahertz element, which is different from the present disclosure and has the current-voltage characteristic indicated by the characteristic line L2 in FIG. I came up with the idea of arranging resistance elements (not shown) in parallel. However, in such a method, in the conduction between the first electrode 13 and the second electrode 14, in addition to the path through the InGaAs layer 125 (quantum well layer) of the active element 12, A path is formed. In the conduction path via this resistance element, current flows through the resistance element, which causes power loss. Further, in the method of suppressing parasitic oscillation using a resistive element, there is a possibility that the detection operation becomes unstable due to variations in the resistance value of the resistive element used. On the other hand, since the terahertz element A1 does not have a conductive path via a resistive element, the aforementioned power loss can be suppressed. In addition, since the terahertz element A1 does not use a resistive element, it is possible to suppress instability of the detection operation due to variations in the resistance value of the resistive element.

6 to 8 show a terahertz device according to a second embodiment of the present disclosure. The terahertz element B1 of the second embodiment performs a terahertz wave detection operation and a terahertz wave oscillation operation. A terahertz device B1 includes a detection section 1, an oscillation section 2, and a support substrate 3. FIG.

FIG. 6 is an example of a schematic diagram of a planar pattern of the terahertz element B1. FIG. 7 is an example of a schematic diagram of a cross section of the oscillation section 2 of the terahertz element B1. FIG. 8 is an example of a schematic cross-sectional view of the terahertz element B1, and corresponds to the enlarged cross-sectional view of the essential part of FIG.

The oscillator 2 oscillates terahertz waves. The oscillation section 2 includes a semiconductor substrate 21, an active element 22, a first electrode 23, a second electrode 24 and an insulating layer 25, as shown in FIG. The semiconductor substrate 21 can be configured similarly to the semiconductor substrate 11 . Active device 22 may be configured similarly to active device 12 . First electrode 23 and second electrode 24 may be configured similarly to first electrode 13 and second electrode 14, respectively. Accordingly, the first electrode 23 includes an antenna portion 231 , a feeder portion 232 and a pad electrode portion 233 , and the second electrode 24 includes an antenna portion 241 , a feeder portion 242 and a pad electrode portion 243 . The antenna units 231 and 241 can be configured similarly to the antenna units 131 and 141, respectively. Feeder sections 232 and 242 may be configured similarly to feeder sections 132 and 142, respectively. The pad electrode portions 233 and 243 may be configured similarly to the pad electrode portions 133 and 143, respectively. The insulating layer 25 can be configured similarly to the insulating layer 15 . 6 and 8, the insulating layer 25 is omitted.

Active device 22, like active device 12, is typically an RTD. The active element 22 may be composed of a diode or a transistor other than the RTD. Examples of such diodes and transistors include tannet diodes, impud diodes, GaAs-based FETs, GaN-based FETs, high electron mobility transistors, heterojunction bipolar transistors, and the like. Active elements 22 are formed on a semiconductor substrate 21 . Active element 22 is electrically connected to first electrode 23 and second electrode 24 .

As with the active element 12, the active element 22 is formed by laminating a plurality of semiconductor layers. As shown in FIG. 8, an InGaAs layer 221a is arranged on the semiconductor substrate 21 . The InGaAs layer 221a is heavily doped with an n-type impurity. An InGaAs layer 222a is arranged on the InGaAs layer 221a. The InGaAs layer 222a is doped with an n-type impurity. An InGaAs layer 223a is arranged on the InGaAs layer 222a. The InGaAs layer 223a is not doped with impurities. An AlAs layer 224a is arranged on the InGaAs layer 223a, an InGaAs layer 225 is arranged on the AlAs layer 224a, and an AlAs layer 224b is arranged on the InGaAs layer 225. FIG. The AlAs layer 224a, the InGaAs layer 225 and the AlAs layer 224b constitute the RTD section. The InGaAs layer 225 is a quantum well layer, and both the AlAs layers 224a and 224b are tunnel barrier layers. An InGaAs layer 223b is arranged on the AlAs layer 224b. The InGaAs layer 223b is not doped with impurities. An InGaAs layer 222b is arranged on the InGaAs layer 223b. The InGaAs layer 222b is doped with an n-type impurity. An InGaAs layer 221b is arranged on the InGaAs layer 222b. The InGaAs layer 221b is heavily doped with n-type impurities. A second electrode 24 is arranged on the InGaAs layer 221b.

The AlAs layer 224a, the InGaAs layer 225, and the AlAs layer 224b constitute the RTD portion of the active element 22. FIG. The InGaAs layer 225 is a quantum well layer, and the AlAs layers 224a and 224b are tunnel barrier layers, respectively. The InGaAs layer 225 is relatively thicker than the AlAs layers 224a, 224b. The indium content in the InGaAs layer 225 is relatively higher than the indium content in the other layers containing indium (the InGaAs layers 221a to 223a and 221b to 223b).

The InGaAs layer 125 is formed thicker than the InGaAs layer 225 . That is, the quantum well layers of active device 12 are thicker than the quantum well layers of active device 22 . For example, the thickness of the InGaAs layer 125 is about 110% or more of the thickness of the InGaAs layer 225 and about the critical thickness of the InGaAs layer 125 or less.

The InGaAs layer 125 has a higher indium content than the InGaAs layer 225 . That is, the indium content in the quantum well layers of active device 12 is greater than the indium content in the quantum well layers of active device 22 . For example, the indium content in the InGaAs layer 125 is about 105-117% of the indium content in the InGaAs layer 225 .

In this embodiment, the active element 22 is an example of the "second active element" described in the claims. Also, the InGaAs layer 225 is an example of the "second quantum well layer" described in the claims.

Oscillator 2 has a current-voltage characteristic indicated by characteristic line L2 in FIG. 5, for example. Therefore, the current-voltage characteristic of the oscillator 2 has a negative resistance region. A bias voltage having a voltage value in the negative resistance region is applied to the first electrode 23 and the second electrode 24 of the oscillation section 2 .

A support substrate 3 supports the detection section 1 and the oscillation section 2 . Semiconductor substrates 11 and 21 are arranged on the support substrate 3 . Support substrate 3 is made of Si (silicon), for example. That is, the support substrate 3 is a Si substrate. Support substrate 3 may be doped with Fe (iron), for example.

The terahertz element B1 includes the detection section 1, like the terahertz element A1. The detection unit 1 has the current-voltage characteristic indicated by the characteristic line L1 in FIG. 5, as described above. Therefore, like the terahertz element A1, the terahertz element B1 can prevent the operation of detecting terahertz waves from becoming unstable, so that the detection accuracy of the terahertz waves can be improved.

The terahertz element B1 includes a detection section 1 that detects terahertz waves and an oscillation section 2 that oscillates terahertz waves. Therefore, the terahertz element B1 functions both as a terahertz wave detection device and as a terahertz wave oscillation device.

9 and 10 show a terahertz device according to a third embodiment of the present disclosure. The terahertz element C1 of the third embodiment does not include the support substrate 3 and differs in the structures of the detection section 1 and the oscillation section 2 from the terahertz element B1.

FIG. 9 is a schematic diagram of a planar pattern of the terahertz element C1. FIG. 10 is an enlarged cross-sectional view of the main part of the terahertz element C1. The schematic diagram of the cross section shown in FIG. 10 corresponds to FIGS. 4 and 8. FIG.

The terahertz element C1 does not have the support substrate 3 as described above. The terahertz element C1 includes a semiconductor substrate 4 instead of the semiconductor substrate 11 of the detection section 1 and the semiconductor substrate 21 of the oscillation section 2 .

The semiconductor substrate 4, like the semiconductor substrates 11 and 21, is a semi-insulating substrate made of a semiconductor material. A constituent material of the semiconductor substrate 4 is, for example, InP. On the semiconductor substrate 4, an InGaAs layer 121a of the detection section 1 and an InGaAs layer 221a of the oscillation section 2 are arranged. The InGaAs layer 121 a and the InGaAs layer 221 a are separated from each other on the semiconductor substrate 4 . In other words, the detection section 1 excluding the InGaAs layer 121a and the oscillation section 2 excluding the InGaAs layer 221a are arranged on the semiconductor substrate 4 and separated from each other. The semiconductor substrate 4 is obtained by integrally forming the semiconductor substrate 11 of the detecting section 1 and the semiconductor substrate 21 of the oscillating section 2 .

The terahertz element C1 includes the detection section 1, like the terahertz element A1. The detection unit 1 has the current-voltage characteristic indicated by the characteristic line L1 in FIG. 5, as described above. Therefore, like the terahertz element A1, the terahertz element C1 can prevent the operation of detecting terahertz waves from becoming unstable, so that the detection accuracy of the terahertz waves can be improved.

Like the terahertz element B1, the terahertz element C1 includes a detection section 1 and an oscillation section 2. FIG. Therefore, the terahertz element C1 functions both as a terahertz wave detection device and as a terahertz wave oscillation device, similarly to the terahertz element B1.

The terahertz device according to the present disclosure is not limited to the above-described embodiments. The specific configuration of each part of the terahertz device of the present disclosure can be changed in various ways.

The terahertz device according to the present disclosure includes embodiments related to the following notes.
[Appendix 1]
Equipped with a detection unit that detects terahertz waves,
The detection unit is
a semiconductor substrate;
a first semiconductor layer overlying the semiconductor substrate, a first quantum well layer overlying the first semiconductor layer, and a second semiconductor layer overlying the first quantum well layer; a first active device comprising;
a first electrode formed on the semiconductor substrate and connected to the first semiconductor layer;
a second electrode formed on the semiconductor substrate and connected to the second semiconductor layer;
and
the second electrode is conductive to the first electrode only through a conductive path through the first quantum well layer;
The detection unit has a nonlinear current-voltage characteristic,
In the current-voltage characteristics, when a forward voltage is applied to the first active element, the larger the voltage value of the forward voltage, the larger the current flowing through the first active element. terahertz element.
[Appendix 2]
In the characteristic line of the current-voltage characteristic, a first curve portion in which the differential coefficient of the characteristic line decreases as the voltage value of the forward voltage increases, and the differentiation of the characteristic line increases as the voltage value of the forward voltage increases. 2. The terahertz device according to appendix 1, further comprising a second curved portion with a larger coefficient.
[Appendix 3]
The terahertz device according to appendix 2, wherein the current-voltage characteristic includes a boundary point at which the first curved portion and the second curved portion are switched.
[Appendix 4]
The terahertz device according to appendix 2 or appendix 3, wherein the voltage value at the second curved portion is higher than the voltage value at the first curved portion.
[Appendix 5]
The terahertz element according to any one of appendices 1 to 4, wherein the first electrode and the second electrode have an antenna structure for detecting terahertz waves.
[Appendix 6]
The first active element is any one of a resonant tunneling diode, a tannet diode, an impatt diode, a GaAs-based field effect transistor, a GaN-based field effect transistor, a high electron mobility transistor, or a heterojunction bipolar transistor. 6. The terahertz device according to any one of 1 to Supplementary Note 5.
[Appendix 7]
It is further equipped with an oscillator that oscillates terahertz waves,
The oscillation unit includes a second active element different from the first active element,
7. The terahertz device according to any one of Appendixes 1 to 6, wherein the second active device includes a second quantum well layer different from the first quantum well layer.
[Appendix 8]
8. The terahertz device according to appendix 7, wherein the first quantum well layer is thicker than the second quantum well layer.
[Appendix 9]
9. The terahertz device according to appendix 8, wherein the thickness of the first quantum well layer is 110% or more of the thickness of the second quantum well layer, and the critical film thickness of the first quantum well layer or less.
[Appendix 10]
both the first quantum well layer and the second quantum well layer contain indium;
The terahertz device according to any one of appendices 7 to 9, wherein the indium content in the first quantum well layer is higher than the indium content in the second quantum well layer.
[Appendix 11]
11. The terahertz device according to appendix 10, wherein the indium content in the first quantum well layer is 105 to 117% of the indium content in the second quantum well layer.
[Appendix 12]
The second active element is any one of a resonant tunneling diode, a tannet diode, an impatt diode, a GaAs-based field effect transistor, a GaN-based field effect transistor, a high electron mobility transistor, or a heterojunction bipolar transistor. 12. The terahertz device according to any one of items 7 to 11.

A1, B1, C1: terahertz element 1: detection unit 11: semiconductor substrate 12: active elements 121a to 123a, 121b to 123b: InGaAs layers 124a, 124b: AlAs layer 125: InGaAs layer 13: first electrode 131: antenna unit 132: feeder portion 133: pad electrode portion 14: second electrode 141: antenna portion 142: feeder portion 143: pad electrode portion 15: insulating layer 2: oscillation portion 21: semiconductor substrate 22: active elements 221a-223a, 221b- 223b: InGaAs layers 224a, 224b: AlAs layer 225: InGaAs layer 23: first electrode 24: second electrode 25: insulating layer 3: support substrate 4: semiconductor substrate L1: characteristic line L11: first curve portion L12: Second curve portion L2: Characteristic line P1: Boundary point

Claims (13)

Equipped with a detection unit that detects terahertz waves,
The detection unit is
a semiconductor substrate;
a first semiconductor layer overlying the semiconductor substrate, a first quantum well layer overlying the first semiconductor layer, and a second semiconductor layer overlying the first quantum well layer; a first active device comprising;
a first electrode formed on the semiconductor substrate and connected to the first semiconductor layer;
a second electrode formed on the semiconductor substrate and connected to the second semiconductor layer;
the second electrode is conductive to the first electrode only through a conductive path through the first quantum well layer;
The detection unit has a nonlinear current-voltage characteristic,
In the current-voltage characteristics of the detection unit , when a forward voltage is applied to the first active element, the current value flowing through the first active element decreases as the voltage value of the forward voltage increases. A terahertz device , wherein there is no negative resistance region, and the current value flowing through the first active device increases as the voltage value of the forward voltage increases. In the characteristic line of the current-voltage characteristic of the detection unit , a first curve portion in which the differential coefficient of the characteristic line decreases as the voltage value of the forward voltage increases, and the and a second curve portion where the derivative of the characteristic line increases,
The terahertz device according to claim 1. In the current-voltage characteristic of the detection unit , there is a boundary point at which the first curve portion and the second curve portion switch,
The terahertz device according to claim 2. the voltage value at the second curve portion is greater than the voltage value at the first curve portion;
The terahertz device according to claim 2 or 3. The first electrode and the second electrode have an antenna structure for detecting terahertz waves,
The terahertz device according to any one of claims 1 to 4. The first active element is either a resonant tunneling diode, a tannet diode, an impatt diode, a GaAs-based field effect transistor, a GaN-based field effect transistor, a high electron mobility transistor, or a heterojunction bipolar transistor.
The terahertz device according to any one of claims 1 to 5. It is further equipped with an oscillator that oscillates terahertz waves,
The oscillator includes a second active element including a second quantum well layer ,
The terahertz device according to any one of claims 1 to 6. In the current-voltage characteristics of the oscillation section, when a forward voltage is applied to the second active element, the value of the current flowing through the second active element decreases as the voltage value of the forward voltage increases. has a negative resistance region,
The terahertz device according to claim 7. the first quantum well layer is thicker than the second quantum well layer;
The terahertz device according to claim 7 or 8 . The thickness of the first quantum well layer is 110% or more of the thickness of the second quantum well layer and the critical thickness of the first quantum well layer or less.
The terahertz device according to claim 9 . both the first quantum well layer and the second quantum well layer contain indium;
The indium content in the first quantum well layer is higher than the indium content in the second quantum well layer,
The terahertz device according to any one of claims 7 to 10 . The indium content in the first quantum well layer is 105 to 117% of the indium content in the second quantum well layer.
The terahertz device according to claim 11 . The second active element is either a resonant tunneling diode, a tannet diode, an impatt diode, a GaAs-based field effect transistor, a GaN-based field effect transistor, a high electron mobility transistor, or a heterojunction bipolar transistor.
The terahertz device according to any one of claims 7 to 12 .

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