JPH05275717A - Magnetic resistance element - Google Patents

Abstract

PURPOSE:To realize a large peak/valley ratio in a current-voltage characteristic and to operate a negative resistance element at room temperature by a method wherein an excess electric current is suppressed. CONSTITUTION:An n-GaAs conductive layer 2, an i-AlAs barrier layer 3a, an f-GaAs well layer 3b, an i-AlAs barrier layer 3a and an n-GaAs conductive layer 2 are formed sequentially; a double barrier region 3A which forms a resonance level ER is formed of the i-AlAs barrier layer 3a, the i-GaAs well layer 3b and the i-AlAs barrier layer 3a. The film thickness of the i-AlAs barrier layers 3a and the i-GaAs well layer 3b is set so as to enhance quantum- dynamic reflection with reference to electrons whose energy is higher than the potential barrier height DELTAEc of the barrier layers 3a. The Fermi level EF of the n-GaAs conductive layer 2 is set lower than the resonance level ER which is generated by the double barrier region 3A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative resistance element having negative resistance characteristics.

[0002]

2. Description of the Related Art FIG. 12 shows a conventional negative resistance element. This is called a double barrier resonance tunneling diode 51, and includes an n-GaAs layer 52 and an i-AlA.
s barrier layer 53, i-GaAs well layer 54, i-Al
The resonant tunneling diode is composed of an As barrier layer 53 and an n-GaAs layer 52, and has double barrier layers 53, 53.

The negative resistance characteristic is, as shown in FIG.
Since the current-voltage characteristic has a region having a gradient opposite to that of the ohmic characteristic, the negative resistance characteristic depends on the total current flowing through the element. In the double barrier resonance tunneling diode 51, the current (or current density) J across the element is mainly determined by two components as shown in FIG. 12, and is expressed as J = J _RT + J _EX . Here, J _RT is a tunnel current due to resonant tunneling, and J _EX is a surplus current that mainly thermally distributed electrons flow on the barrier layer 53 without resonating.

In order to obtain the desired negative resistance characteristic, it is necessary to increase the peak value Ip and decrease the valley value Iv in the current-voltage characteristic as shown in FIG. In the double barrier resonance tunneling diode 51, the peak value Ip is determined mainly by the tunnel current J _RT , and the peak value Ip can be increased by increasing the tunnel current J _RT . Further, the valley value Iv is mainly the surplus current J _EX.
The valley value Iv can be reduced by reducing the surplus current J _EX . Therefore, in order to obtain the desired negative resistance characteristic in the double barrier resonance tunneling diode 51, it is important to increase the tunnel current J _RT and decrease the surplus current J _EX . Therefore, conventionally, the barrier layer is formed of AlAs having the maximum barrier height for the purpose of reducing the excess current J _EX .

[0005]

However, in such a conventional double barrier resonance tunneling diode, since the barrier height is limited by the material, a sufficient barrier height cannot be realized, and the current -The peak / valley ratio (that is, Ip / Iv) in the voltage characteristic
There was a problem that could not be made too large.

The present invention has been made in view of the drawbacks of the above conventional examples, and an object thereof is to provide a negative resistance element capable of realizing a large peak / valley ratio in the current-voltage characteristic. To provide.

[0007]

A first negative resistance element of the present invention comprises a multiple barrier region composed of a barrier layer and a well layer, and conductive layers formed on both sides of the multiple barrier region. In the resonant tunneling diode, the thickness and composition of the barrier layer and the well layer forming the multi-barrier region are set to a virtual barrier by quantum mechanical reflection action with respect to incident electrons having energy higher than the potential of the barrier layer. It is characterized in that it is set to form.

Further, in the first negative resistance element, it is preferable that the Fermi level of the conductive layer is set lower than the resonance level generated by the multiple barrier region.

The second negative resistance element of the present invention comprises a superlattice barrier region constituted by a superlattice well layer and a superlattice barrier layer, and conductive layers formed on both sides of the superlattice barrier region. In the negative resistance element, the film thickness and composition of the superlattice well layer and the superlattice barrier layer forming the superlattice barrier region are set to an incident electron having an energy higher than the potential of the superlattice barrier layer. , It is characterized in that it is set so as to form a virtual barrier by the quantum mechanical reflection effect.

In the second negative resistance element, a barrier layer is formed between the conductive layer and the superlattice barrier region, and the thickness of this barrier layer constitutes the superlattice barrier region. It is preferable to set the thickness larger than that of the superlattice barrier layer.

A third negative resistance element of the present invention comprises a multi-barrier region composed of a barrier layer and a well layer, and a superlattice well layer and a superlattice barrier layer formed on both sides of the multi-barrier region. A negative resistance element comprising a configured superlattice barrier region and a conductive layer formed outside the superlattice barrier region, the superlattice well layer and the superlattice barrier constituting the superlattice barrier region. It is characterized in that the film thickness and composition of the layer are set so as to form a virtual barrier by the quantum mechanical reflection action with respect to incident electrons having an energy higher than the potential of the superlattice barrier layer.

Further, in the third negative resistance element, the resonance level generated by the multiple barrier region may be set so as to be located within the miniband of the superlattice barrier region.

Further, in the second and third negative resistance elements, the Fermi level of the conductive layer is preferably set lower than the miniband of the superlattice barrier region.

[0014]

In the first negative resistance element of the present invention, the film thickness and composition of the multiple barrier region forming the resonance level are determined by the potential of the barrier layer in the multiple barrier region by multiple interference of quantum mechanical reflection. Since the setting is made so as to enhance the reflection with respect to incident electrons having a higher energy than that, it is possible to suppress the surplus current that has conventionally flowed over the multiple barrier region. As a result, an element having a large peak / valley ratio even at room temperature can be manufactured, and good negative resistance characteristics can be obtained.

In the second negative resistance element of the present invention, the superlattice barrier region is sandwiched by conductive layers having a low potential, and the superlattice barrier region is based on the concept of multiple quantum barriers. Since the composition and thickness of the superlattice well layer and the superlattice barrier layer are designed to enhance the quantum mechanical reflection for electrons having higher energy than the barrier height of the potential barrier of the superlattice barrier layer, A virtual barrier is formed even for electrons having an energy higher than the barrier height of the superlattice barrier layer, and the surplus current can be suppressed. As a result, an element having a large peak / valley ratio even at room temperature can be manufactured, and good negative resistance characteristics can be obtained.

Further, in the third negative resistance element of the present invention, superlattice barrier regions are formed on both sides of the multiple barrier region, and the superlattice barrier region is formed on the basis of the concept of multiple quantum barriers. Since the composition and thickness of the well layer and the superlattice barrier layer are designed to enhance quantum mechanical reflection for electrons having higher energy than the barrier height of the superlattice barrier layer, A virtual barrier is formed even for electrons having an energy higher than the barrier height, and the surplus current can be suppressed. Further, when the resonance level generated by the multiple barrier region is set to be located within the miniband of the superlattice barrier region, electrons are injected into the resonance level of the multiple barrier region through the miniband of the superlattice barrier region. .. As a result, an element having a large peak / valley ratio can be manufactured at room temperature, and good negative resistance characteristics can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a GaAs / A according to an embodiment of the present invention.
lAs-based double barrier resonance tunneling diode 1
FIG. 6 is a band structure diagram of a conduction band in the absence of bias, showing the configuration of FIG. This is the n-GaAs conductive layer 2, i-AlA
s barrier layer 3a, i-GaAs well layer 3b, i-Al
As barrier layer 3a and n-GaAs conductive layer 2
The -AlAs barrier layer 3a, the i-GaAs well layer 3b, and the i-AlAs barrier layer 3a form a double barrier region 3A forming a resonance level E _R.

Here, i-AlAs that creates the resonance level E _R
The thickness of the barrier layer 3a and the i-GaAs well layer 3b is
Barrier height ΔEc of the potential barrier of the barrier layer 3a
It is set to enhance the reflection quantum mechanically for electrons with higher energies. Therefore, in the double barrier region 3A, the barrier height Δ of the barrier layer 3a is
A virtual barrier 4 having a barrier height ΔEc + ΔUew higher than Ec is formed, and a resonance level E _R is formed in the virtual barrier 4. For example, two i-Al
The thickness of the As barrier layer 3a is 11.3Å, and i-GaA
The thickness of the s well layer 3b is 14.1Å. Also,
The Fermi level E _F of the n-GaAs conductive layer 2 is set lower than the resonance level E _R generated by the double barrier region 3A.

Thus, if the double barrier region 3A is formed so as to obtain a virtual potential barrier height ΔEc + ΔUew that is higher than the classical potential barrier height ΔEc of the barrier layer 3a, electrons will cross the double barrier region 3A. Virtual barrier 4 in order to become excess current J _EX
Must have a larger energy than the barrier height ΔEc + ΔUew of. Therefore, it is possible to form a virtual barrier 4 with respect to electrons having energy higher than the height ΔEc classical potential barrier which has reduced the negative resistance characteristic as excess current J _EX, excess current J _EX
Can be reduced. On the other hand, double barrier area 3
An electron having an energy equal to the resonance level E _{R of} A has a large transmittance due to the tunnel effect, so that it passes through the double barrier region 3A by the tunnel effect and the tunnel current J
_RT flows. As a result, a large peak / valley ratio can be obtained in the current-voltage characteristic even at room temperature, and the characteristic as the negative resistance element is improved. Further, since the Fermi level E _F of the n-GaAs conductive layer 2 is lower than the resonance level E _R , the tunnel current J _RT can be suppressed when there is no bias.

FIG. 2 shows the n-GaAs conductivity of the double barrier region 3A when the i-AlAs barrier layer 3a has a thickness of 11.3Å and the i-GaAs well layer 3b has a thickness of 14.1Å without bias. The reflectance of incident electrons from the layer 2 side is shown, the horizontal axis represents the energy of the incident electrons, and the vertical axis represents the reflectance. This Figure 2
According to the reflectance curve of, the reflectance is kept close to 1 even for the electron having the energy of the barrier height ΔEc (= 956.4 meV) or more of the barrier layer 3a of the double barrier region 3A, and the energy is The electrons of ΔEc + ΔUew or less are reflected by the double barrier region 3A and cannot pass through the double barrier region 3A. Therefore, as shown in FIG. 1, the height of the potential barrier in the double barrier region 3A virtually increases to ΔEc + ΔUew, and the surplus current J _EX can be reduced by the virtual barrier 4. On the other hand, according to the reflectance curve of FIG. 2, the reflectance is 0 for electrons having the energy equal to the resonance level E _R, and a large tunnel current J _RT passes through the resonance level E _R. It flows into the double barrier region 3A.

In this embodiment, the device material is not limited to the GaAs / AlAs system. Further, the well layer, the barrier layer, and the like are not limited to those that are lattice-matched, and a lattice-mismatched system may be used. Further, different materials may be used for the conductive layer and the well layer.

FIG. 3 shows GaAs according to another embodiment of the present invention.
FIG. 4 is a band structure diagram (without bias) of a conduction band showing a configuration of a triple barrier resonance tunneling diode 5 of / AlAs system. This is the n-GaAs conductive layer 2, i-Al
As barrier layer 3a, i-GaAs well layer 3b, i-A
lAs barrier layer 3a, i-GaAs well layer 3b, i-
The AlAs barrier layer 3a and the n-GaAs conductive layer 2 are used. The i-AlAs barrier layer 3a, the i-GaAs well layer 3b, the i-AlAs barrier layer 3a, the i-GaAs well layer 3b, and the i-AlAs barrier layer 3a are used to form 2 A triple barrier region 3B forming one resonance level E _R1 and E _R2 is formed.

Here, each i- which makes the resonance levels E _R1 and E _R2
AlAs barrier layer 3a and each i-GaAs well layer 3b
The film thickness is set so as to quantum-mechanically enhance reflection of electrons having energy higher than the height ΔEc of the classical potential barrier of the barrier layer 3a. Therefore, in the triple barrier region 3B, the barrier height ΔEc + ΔUe higher than the barrier height ΔEc of the barrier layer 3a.
The virtual barrier 4 of t is formed, and the resonance levels E _R1 and E _R2 are further formed in the virtual barrier 4. For example, the thickness of each i-AlAs barrier layer 3a is 11.3Å, and the thickness of each i-GaAs well layer 3b is 14.1Å. Further, the Fermi level E _F of the n-GaAs conductive layer 2 is set to be lower than both the resonance levels E _R1 and E _R2 generated by the triple barrier region 3B.

In the structure shown in FIG. 4, each i-AlAs barrier layer 3a has a thickness of 11.3Å, and each i-GaAs well layer 3 has a thickness of 11.3Å.
The reflectance for incident electrons from the side of the n-GaAs conductive layer 2 in the non-biased triple barrier region 3B in which the thickness of b is 14.1Å is shown. According to the reflectance curve of FIG. 4, the barrier layer 3a of the triple barrier region 3B is
The reflectance is kept close to 1 even for the electrons having the energy equal to or higher than the barrier height ΔEc (= 956.4 meV), and the electrons having the energy equal to or less than ΔEc + ΔUet are reflected by the triple barrier region 3B to form the triple barrier region. Three
You cannot pass B. Therefore, as shown in FIG. 3, the height of the potential barrier of the triple barrier region 3B virtually increases to ΔEc + ΔUet, and the surplus current J _EX can be reduced. On the other hand, according to the reflectance curve of FIG. 4, the reflectance is 0 for the electron having the energy equal to the two resonance levels E _R1 and E _R2 , and the large tunnel current J _RT is the triple barrier region. 3B
Flow through. As a result, a large peak / valley ratio can be obtained even at room temperature, and good negative resistance characteristics can be realized.

FIG. 5 is a band structure diagram (without bias) showing the configuration of the negative resistance element 6 according to still another embodiment of the present invention. The negative resistance element 6 includes an n-GaAs conductive layer 2, an i-AlAs barrier layer 7, and an i-AlAs / GaA.
s superlattice barrier region 8, i-AlAs barrier layer 7, n-
The superlattice barrier region 8 is formed by laminating the i-AlAs superlattice barrier layer 8a and the i-GaAs superlattice well layer 8b.

Here, the i-AlAs superlattice barrier layer 8a is formed.
The superlattice barrier region 8 formed by alternately laminating the i-GaAs superlattice well layers 8b is introduced on the basis of the concept of a multi-quantum barrier (hereinafter, referred to as MQB). The bottom of the conduction band changes periodically with an amplitude of ΔEc (barrier height of the barrier layer 8a), and electrons having energy higher than the height ΔEc of the potential barrier of the superlattice barrier layer 8a. Is set to enhance the reflection mechanically with respect to.

By constructing such an MQB, the reflectance is kept close to 1 even for incident electrons having an energy higher than the height ΔEc of the potential barrier of the superlattice barrier layer 8a, and the superlattice barrier region 8 is formed. The height of the potential barrier can be virtually increased. That is, when an electron of energy E enters the superlattice barrier region 8, the electron (electron wave) is quantum mechanically reflected at a potential discontinuity point. Therefore, the superlattice barrier layer 8a is controlled so that the phase of the reflected wave of electrons at each discontinuity can be controlled.
And if the physical quantity of the superlattice well layer 8b is set appropriately,
The energy barrier for incident electrons can be artificially controlled. For example, the superlattice well layer 8b and the superlattice barrier layer 8
The thicknesses d ₁ and d ₂ of a may be set so as to satisfy the following expressions, respectively. {2m ₁ ^* · (E−ΔE)} ^1/2 · (d ₁ / h) = 1/4 …… {2m ₂ ^* · (E−ΔE)} ^1/2 · (d ₂ / h) = 1 / 4 Here, m ₁ ^* and m ₂ ^* are effective masses of electrons in the superlattice well layer 8b and the superlattice barrier layer 8a, and h is Planck's constant. Each of the superlattice well layer 8b and the superlattice barrier layer 8a is satisfied so that these equations and equations are satisfied, that is, the phase difference of the reflected wave of the electron reflected by each superlattice barrier layer 8a becomes an integral multiple of π. When the physical quantity is set, the phases of the reflected waves of the electrons strengthen each other at each discontinuity point, and the incident electrons are strongly reflected by the superlattice barrier region 8, so that the energy barrier for the electrons is equivalently increased. .. As a result, as shown in FIG. 5, a virtual barrier 9 having a barrier height ΔEc + ΔUes higher than the barrier height ΔEc of the superlattice barrier layer 8a is formed in the superlattice barrier region 8.

Further, in the superlattice barrier region 8, MQB
So that the potential E penetrates through the virtual barrier 9
_A mini band (allowable band) 10 is formed between ₁ and E ₂ . Although the electrons in the conduction band are explained here,
Virtual barriers and minibands also hold for holes in the valence band.

The i-AlAs barrier layer 7 is made of i-G.
It is designed to have a thickness larger than that of the i-AlAs superlattice barrier layer 8a in contact with the aAs superlattice well layer 8b, and the tunnel current J flowing through the miniband 10 in a low electric field state.
_It plays a role in suppressing _RT . That is, i-Al
By controlling the thickness of the As barrier layer 7, it is possible to control the current amount J _RT that tunnels the superlattice barrier region 8.

Further, the superlattice barrier layer 8a is formed so that the bottom E1 of the miniband 10 formed by the superlattice barrier region 8 is higher than the Fermi level E _{F of the} n-GaAs conductive layer 2.
The film thickness of the superlattice well layer 8b and the Fermi level E _F are designed so that the tunnel current J in the absence of bias is
_It suppresses _RT .

As a result, the virtual barrier 9 of the MQB suppresses the surplus current J _EX due to the electrons having energy higher than the height ΔEc of the potential barrier of the superlattice barrier layer 8a, while tunneling the miniband 10. A current J _RT flows, and a negative resistance characteristic capable of operating at room temperature with a large peak / valley ratio can be realized.

FIG. 6 shows the i-GaAs superlattice well layer 8b.
Is 5 atomic layers, the thickness of the i-AlAs superlattice barrier layer 8a is 4 atomic layers, and 10 pairs of the superlattice well layer 8b and the superlattice barrier layer 8a are formed from the n-GaAs conductive layer 2 side. The reflectance for incident electrons is shown, the horizontal axis represents the energy of incident electrons, and the vertical axis represents the reflectance. According to the reflectance curve of FIG. 6, the height ΔEc (= 95 of the superlattice barrier layer 8a in the superlattice barrier region 8).
The reflectance is kept close to 1 even for an electron having an energy ΔEc + ΔUes (6.4 meV) or more (ΔEc + ΔUes≈1.6 × ΔEc in FIG. 6), and an electron having an energy of ΔEc + ΔUes or less is a superlattice barrier region. 8
And cannot pass through the superlattice barrier region 8. Therefore, as shown in FIG. 5, the height of the potential barrier of the superlattice barrier region 8 is virtually ΔEc +.
ΔUes≈1.6 × ΔEc, and surplus current J _EX
Can be reduced. On the other hand, according to the reflectance curve of FIG. 6, the barrier height ΔEc of the superlattice barrier layer 8a is 0.
The reflectivity sharply decreases around the energy 0.5 × ΔEc of about 5 times, and the miniband 10 is formed in the superlattice barrier region 8 as shown in FIG. 5 and passes through the miniband 10. And a large tunnel current J _RT flows in the superlattice barrier region 8. Further, when the carrier concentration of the n-GaAs conductive layer 2 is 1 × 10 ¹⁸ cm ⁻³ , the Fermi level E _F is about 53 meV and can be lower than that of the miniband 10.

In this embodiment also, the element material is GaA.
Not limited to s / AlAs system. Further, the superlattice well layer, the superlattice barrier layer, and the like are not limited to those that are lattice-matched, and a lattice-mismatched system may be used.

FIG. 7 (a) is a structural diagram showing the structure of a negative resistance element 11 according to still another embodiment of the present invention, FIG. 7 (b).
FIG. 4 is a band structure diagram of a conduction band in the vicinity of the superlattice barrier region 8. MBE on the n-GaAs substrate 12
N-GaAs conductive layer 2 (film thickness 2.0 μ
m, carrier density 5 × 10 ¹⁷ cm ⁻³ ), undoped-Ga
As spacer layer 13 (film thickness 100Å), i-Al _0.2 G
a _0.8 As barrier layer 7 (film thickness 170Å), i-superlattice barrier region 8 (film thickness 0.2 μm), i-Al _0.2 Ga _0.8 A
s barrier layer 7 (film thickness 170Å), undoped-GaAs spacer layer 13 (film thickness 100Å), n-GaAs conductive layer 2
(Film thickness 2.0 μm, carrier density 5 × 10 ¹⁷ cm ⁻³ ),
n-GaAs cap layer 14 is the (film thickness 0.2 [mu] m, the carrier density of 5 × 10 ^{1 8} cm ^-3) that are sequentially formed.
Here, as shown in FIG. 7B, the i-superlattice barrier region 8 includes 25 layers of i-GaAs superlattice well layers 8b (thickness 33.9Å) and 24 layers of i-Al _0.2 Ga _0.8. As superlattice barrier layers 8a (thickness 33.9Å) are alternately laminated. Furthermore, the carrier concentration of the n-GaAs conductive layer 2 is 5 × 10 ¹⁷ cm ⁻³ , and the Fermi level E _F
Is located below the bottom of the miniband.

Also in such a negative resistance element 11,
An operation similar to that of the negative resistance element 6 shown in FIG. 5 can be performed, a large peak / valley ratio can be obtained at room temperature, and excellent negative resistance characteristics can be achieved.

FIG. 8 is a band structure diagram showing the structure of the negative resistance element 15 according to another embodiment of the present invention when no bias is applied. In this embodiment, the conductive layer 2 and the superlattice well layer 8b are made of different materials, so that the bottom layers of the conductive layer 2 and the superlattice well layer 8b have different energy levels. In addition, the barrier layer 7 and the superlattice barrier layer 8
The materials of a are also different, so that the barrier heights of the barrier layer 7 and the superlattice barrier layer 8a are also different.

FIG. 9 is a band structure diagram (without bias) showing the structure of the negative resistance element 16 according to still another embodiment of the present invention. The negative resistance element 16 includes an n-GaAs conductive layer 2, an i-AlAs / GaAs superlattice barrier region 8,
It comprises a double barrier region 3A, an i-AlAs / GaAs superlattice barrier region 8 and an n-GaAs conductive layer 2.

Here, the superlattice barrier region 8 is made of i-Al.
The As superlattice barrier layer 8a and the i-GaAs superlattice well layer 8b are formed in a multi-layered structure.
Based on the concept of B, it is set so as to quantum mechanically enhance reflection of electrons having energy higher than the height ΔEc of the potential barrier of the superlattice barrier layer 8a. As a result, the barrier height ΔE in the superlattice barrier region 8 is higher than the barrier height ΔEc of the superlattice barrier layer 8a.
A virtual barrier 9 of c + ΔUes is formed. Also,
In the superlattice barrier region 8, a miniband (allowable band) 10 is formed between MQ and the potential energies E ₁ and E ₂ .

The double barrier region 3A is made of i-Al.
As barrier layer 3a, i-GaAs well layer 3b and i-
Double barrier region 3A made of AlAs barrier layer 3a
The electron resonance level E _R is formed by. Moreover, the resonance level E _R of the double barrier region 3 A is designed to be located within the miniband 10 formed by the superlattice barrier region 8. That is, the barrier width, the well width, and the composition of the double barrier region 3A are designed so that the energy relationship of E ₁ <E _R <E ₂ is satisfied.

Further, in this embodiment, the bottom E1 of the miniband 10 formed in the superlattice barrier region 8 is n.
The carrier concentration of the n-GaAs conductive layer 2 and the superlattice barrier region 8 are designed to be higher than the Fermi level E _F of the -GaAs conductive layer 2.

As a result, the electrons having energy higher than the barrier height ΔEc of the superlattice barrier layer 8a are reflected by the virtual barrier 9 having the barrier height ΔEc + ΔUes in the superlattice barrier region 8 and flow without resonance conventionally. The surplus current J _EX can be suppressed. Moreover, n-GaAs
Electrons are injected from the conductive layer 2 to the resonance level E _R of the double barrier region 3A through the miniband 10 of the superlattice barrier region 8 and further through the miniband 10 of the other superlattice barrier region 8 to the other n-GaAs. Electrons flow to the conductive layer 2 and a tunnel current J _RT due to resonance tunneling flows. Therefore, it is possible to realize a negative resistance element having a peak / valley ratio even during operation at room temperature.

FIG. 10 is a band structure diagram of the conduction band showing the structure of the negative resistance element 17 according to still another embodiment of the present invention. In this embodiment, different materials are used for the well layer 3b of the double barrier region 3A, the conductive layer 2 and the superlattice well layer 8b, and the bottom of the well layer 3b is formed of the conductive layer 2.
And the bottom of the superlattice well layer 8b. Further, different materials are used for the barrier layer 3a and the superlattice barrier layer 8a of the double barrier region 3A, and the double barrier region 3A
The height of the potential barrier of the barrier layer 3a is lower than the height of the potential barrier of the superlattice barrier layer 8a.

FIG. 11 is a band structure diagram of the conduction band showing the structure of the negative resistance element 18 according to still another embodiment of the present invention. In this embodiment, different materials are used for the well layer 3b of the double barrier region 3A, the conductive layer 2 and the superlattice well layer 8b, and the bottom of the well layer 3b is the bottom of the conductive layer 2 and the superlattice well layer 8b. Have lower than. Further, the barrier layer 3a in the double barrier region 3A and the superlattice barrier layer 8a
And the potential of the barrier layer 3a of the double barrier region 3A is set to be different from that of the superlattice barrier layer 8
It is set higher than the height of the potential barrier of a.

[0044]

According to the present invention, it is possible to suppress the surplus current that has conventionally flowed over the multiple barrier region. In addition, the tunnel current can be controlled by the miniband in the device having the superlattice barrier region.

As a result, at room temperature, a large peak /
It is possible to manufacture an element having a valley ratio, obtain good negative resistance characteristics, and realize a negative resistance element that can operate at room temperature.

[Brief description of drawings]

FIG. 1 is a band structure diagram of a conduction band showing a configuration of a double barrier resonance tunneling diode according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the reflectance of the double barrier region and the energy of incident electrons in the example of the same.

FIG. 3 is a band structure diagram of a conduction band showing a configuration of a triple barrier resonance tunneling diode according to another embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the reflectance of a triple barrier region and the energy of incident electrons in the example of the same.

FIG. 5 is a band structure diagram of a conduction band showing a configuration of a negative resistance element according to still another embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between the reflectance of the superlattice barrier region and the energy of incident electrons in the example of the same.

7A and 7B are a structural view showing a specific structure of a negative resistance element according to still another embodiment of the present invention and a band structure view showing its superlattice barrier region.

FIG. 8 is a band structure diagram of a conduction band showing a configuration of a negative resistance element according to still another embodiment of the present invention.

FIG. 9 is a band structure diagram of a conduction band showing a configuration of a negative resistance element according to still another embodiment of the present invention.

FIG. 10 is a band structure diagram of a conduction band showing a configuration of a negative resistance element according to still another embodiment of the present invention.

FIG. 11 is a band structure diagram of a conduction band showing a configuration of a negative resistance element according to still another embodiment of the present invention.

FIG. 12 is a band structure diagram of a conduction band showing a configuration of a conventional double barrier resonance tunneling diode.

FIG. 13 is a diagram showing an example of current-voltage characteristics having negative resistance characteristics.

[Explanation of symbols]

2 n-GaAs conductive layer 3A double barrier region 3B triple barrier region 3a i-AlAs barrier layer 3b i-GaAs well layer 4 virtual barrier 7 i-AlAs barrier layer 8 superlattice barrier region 8a i-AlAs superlattice barrier layer 8b i -GaAs superlattice well layer 9 virtual barrier 10 miniband E _R resonance level E _F Fermi level

Claims (7)

[Claims] 1. A resonance tunneling diode comprising a multi-barrier region composed of a barrier layer and a well layer, and a conductive layer formed on both sides of the multi-barrier region, wherein the barrier layer and the well constituting the multi-barrier region. A negative resistance element in which the film thickness and composition of the layer are set so as to form a virtual barrier by a quantum mechanical reflection action with respect to incident electrons having an energy higher than the potential of the barrier layer. 2. The negative resistance element according to claim 1, wherein a Fermi level of the conductive layer is set lower than a resonance level generated by the multiple barrier region. 3. A negative resistance element comprising a superlattice barrier region composed of a superlattice well layer and a superlattice barrier layer, and conductive layers formed on both sides of the superlattice barrier region, The film thickness and composition of the superlattice well layer and the superlattice barrier layer forming the lattice barrier region are set to a virtual barrier by quantum mechanical reflection action with respect to incident electrons having energy higher than the potential of the superlattice barrier layer. A negative resistance element set to form a. 4. A barrier layer is formed between the conductive layer and the superlattice barrier region, and the barrier layer is thicker than the superlattice barrier layer forming the superlattice barrier region. The negative resistance element according to claim 3, which is set. 5. A multi-barrier region composed of a barrier layer and a well layer, a super-lattice well layer formed on both sides of the multi-barrier region and a super-lattice barrier region composed of a super-lattice barrier layer, A negative resistance element comprising a conductive layer formed outside a superlattice barrier region, wherein the film thickness and composition of the superlattice well layer and superlattice barrier layer forming the superlattice barrier region A negative resistance element that is set so as to form a virtual barrier by quantum mechanical reflection for incident electrons having energy higher than the potential of the barrier layer. 6. The negative resistance element according to claim 5, wherein the resonance level generated by the multiple barrier region is set so as to be located within the miniband of the superlattice barrier region. 7. The negative resistance element according to claim 3, wherein the Fermi level of the conductive layer is set lower than the miniband of the superlattice barrier region.