JP2003133616A - Gunn diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the oscillation efficiency and the manufacturing reproducibility of a Gunn diode. SOLUTION: A first contact layer 12 consisting of a high density n type GaAs, an active layer 13 consisting of a low density n type GaAs and a second contact layer 14 consisting of a high density n type InGaAlP are sequentially stacked on a semiconductor substrate 11 consisting of a high density n type GaAs. A big area anode electrode 15 for impressing a voltage on the active layer 13 and a small area cathode electrode 16 are arranged on the second contact layer 14. Recesses 20 for defining the parts of the second contact layer 14 and the active layer 13, which are opposed to the cathode electrode 16, in order to specify the areas for functioning as the Gunn diode are cut in from the periphery of the cathode electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Gunn diode used as a microwave or millimeter wave oscillator,
In particular, the present invention relates to a Gunn diode having improved oscillation efficiency and improved manufacturing reproducibility, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Gunn diodes for oscillating microwaves and millimeter waves are usually formed of compound semiconductors such as gallium arsenide (GaAs) and indium phosphide (InP).
In these compound semiconductors, the mobility of electrons is as large as several thousand cm ² / Vsec in a low electric field, whereas in a high electric field, the accelerated electrons transit to a band with a large effective mass and their mobility decreases. As a result, negative differential mobility occurs in the bulk, and as a result, negative differential conductance of the current-voltage characteristic appears, resulting in thermodynamic instability. For this reason, domains are generated and travel from the cathode side to the anode side. As a result of repeating this, an oscillating current (oscillation) is obtained.

In the microwave region, the oscillation frequency f
t is obtained from the traveling distance L and the average drift velocity Vd of the electrons, and ft = Vd / L. Here, the frequency of the direct current becomes the oscillation frequency of the Gunn diode. In the Gunn diode, the oscillation efficiency represented by the ratio of the AC power output to the input DC power is the most important figure of merit, and its improvement is required.

In the case of a millimeter-wave Gunn diode, it is necessary to make the traveling distance of the domain as short as 1 to 2 μm. Moreover, in order to obtain sufficient oscillation efficiency, it is necessary to set the product of the impurity concentration and the thickness of the domain running space (active layer) to a predetermined value (for example, 2 × 10 ¹² / cm ² ), Further, since the oscillation frequency is uniquely determined by the thickness of the active layer, the impurity concentration of the active layer becomes considerably high in a high frequency band such as a millimeter wave. The current density in the operating state is determined by the product of the impurity concentration of the active layer and the saturated electron velocity, and in the millimeter wave band, the temperature of the active layer rises due to the increase of the current density, and the oscillation efficiency decreases.

In order to solve such a problem, the conventional millimeter-wave Gunn diode has a mesa structure so that the size of the element including the active layer can be reduced to several 1
It was formed in a pill-type package having a heat dissipation portion made of diamond or the like, which has a very small diameter of about 0 μm and has a high heat dissipation efficiency.

FIG. 8 shows a sectional view of a conventional Gunn diode 100A having a mesa structure. A high-concentration n-type G is formed on the semiconductor substrate 101 made of high-concentration n-type GaAs by the MBE method.
The first contact layer 102 made of aAs, the active layer 103 made of low-concentration n-type GaAs, and the second contact layer 104 made of high-concentration n-type GaAs are sequentially stacked to reduce the area of the electron transit space. It has a mesa structure.

After the above-mentioned structure, the semiconductor substrate 10
The back surface of No. 1 is thinned, the anode electrode 105 is formed on the back surface of the semiconductor substrate 101, and the cathode electrode 106 is formed on the surface of the second contact layer 104, and then element isolation is performed to form a Gunn diode. To complete.

Gunn diode 10 thus formed
0A is assembled in a pill package 110 as shown in FIG. This pill-type package 110 has a heat dissipation base electrode 111 and a cylinder 112 made of glass or ceramics which serves as an envelope surrounding the Gunn diode 100A. The cylinder 112 is a heat dissipation base electrode 111.
It has a structure brazed to hard. The Gunn diode 100A is electrostatically adsorbed by a bonding tool such as a sapphire material (not shown) and adhered to the heat dissipation base electrode 111.

Further, the gold ribbon 113 connects the Gunn diode 100A and the metal layer provided at the tip of the cylinder 112 by thermocompression bonding or the like. After connecting the gold ribbon 113, a lid-shaped metal disk 114 is brazed onto the cylinder 112, and the assembly into the pill type package 110 is completed.

The conventional Gunn diode is made of GaAs.
On the cathode electrode 106 side of the active layer 103, there is a defect that a portion called a dead zone where a gun domain cannot be generated is generated. The gun domain is the GaAs second contact layer 1 to which the cathode electrode 106 is connected.
Conductive electrons injected from 04 into the GaAs active layer 103 are generated by giving energy necessary for transition from the gamma valley to the L valley. Therefore, the distance traveled by the conduction electrons becomes the dead zone until the energy required for the transition is given.

The shorter the dead zone, the higher the oscillation efficiency, and the higher the ratio of the dead zone to the thickness of the active layer, the lower the oscillation efficiency. For this reason, in order to obtain a frequency oscillation in a high frequency region such as a microwave or a millimeter wave, in a Gunn diode having a thin active layer, the dead zone thickness occupies a large proportion of the active layer thickness. However, there is a drawback that the oscillation efficiency is significantly lowered.

Conventionally, as a method of eliminating this dead zone, as in a Gunn diode 100B shown in FIG.
AlG in place of the second contact body layer 104 of GaAs
Using the second contact layer 107 of aAs, the active layer 1
It has been proposed to inject into the GaAs active layer 103 conduction electrons having an energy corresponding to a conduction band discontinuity ΔEc = 0.26 eV. The injected conduction electrons can easily transit to the L valley, which is a high energy band, so that the occurrence of a dead zone can be suppressed.

[0013]

However, in the conventional gallium arsenide gun diodes 100A and 100B, in order to have the above-mentioned mesa structure, a photoresist is usually used as an etching mask and a chemical wet etching method is used. However, this etching method has a manufacturing difficulty in that the etching progresses not only in the depth direction but also in the lateral direction at the same time, and it is very difficult to control the active layer 103. There was a problem of variation.

Further, when assembling into the pill type package 110, it is difficult to directly visually recognize the heat dissipation base electrode 111, and there is a problem that the assembling work efficiency is very poor.

Further, Gunn diodes 100A, 100
When the pill-type package 110 incorporating B is mounted on a microstrip line (not shown) configured on a flat board, since it is connected by a gold ribbon, a parasitic inductance occurs and variations in characteristics occur. There was the above problem.

An object of the present invention is to provide a highly efficient Gunn diode which eliminates the above-mentioned problems, can be manufactured with good reproducibility, and can suppress the occurrence of dead zones, and a manufacturing method thereof. Is.

[0017]

The invention according to claim 1 is
A high concentration n-type is formed on a semiconductor substrate made of high concentration n-type GaAs.
Type GaAs first semiconductor layer, low concentration n-type GaA
A Gunn diode in which an active layer made of s and a second semiconductor layer made of high-concentration n-type InGaAlP are sequentially stacked, which is arranged on the second semiconductor layer to apply a voltage to the active layer. A first electrode having a small area and a second electrode having a large area; and the second electrode corresponding to the first electrode that is cut from the periphery of the first electrode to at least the lower surface of the second semiconductor layer. And a recess for partitioning a portion of the semiconductor layer and the active layer as a region functioning as a Gunn diode.

The invention according to claim 2 is a high concentration n-type GaA
A gun in which a first semiconductor layer made of high-concentration n-type GaAs, an active layer made of low-concentration n-type GaAs, and a second semiconductor layer made of high-concentration n-type InGaAlP are sequentially stacked on a semiconductor substrate made of s. A first electrode having a small area and a second electrode having a large area, the diode being disposed on the second semiconductor layer for applying a voltage to the active layer;
A portion of the second semiconductor layer and the active layer, which is formed by ion implantation from the periphery of the first electrode to at least the lower surface of the second semiconductor layer and corresponds to the first electrode, functions as a Gunn diode. The gun diode is characterized by including a high resistance layer that is divided as a region.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein the conduction band discontinuity between the second semiconductor layer and the active layer is 0.19 eV to 0.30 eV. A Gunn diode characterized by the above.

A fourth aspect of the present invention is the invention according to any one of the first to third aspects, wherein the composition of InGaAlP of the second semiconductor layer is In _0.48 (Ga _1-x Al _x ) _0.52 P. And a Gunn diode characterized by lattice matching with the active layer.

The invention according to claim 5 is the same as the invention according to claim 4, wherein In _0.48 (Ga _1-x Al _x ) of the second semiconductor layer is provided.
_The gun diode is characterized in that the composition ratio x of Al of _0.52 P is in the range of x = 0 to 0.4.

The invention according to claim 6 is the same as the invention according to claim 4 or 5, wherein In _0.48 (Ga _{1-x) of} the second semiconductor layer is formed.
Al _x ) _0.52P is a Gunn diode characterized in that the composition changes toward the first and second electrodes so that x = 0 on the first and second electrode sides.

The invention according to claim 7 is the invention according to claim 4 or 5.
In the invention, the In of the second semiconductor layer_0.48(Ga_1-x
Al_x)_0.52P has a predetermined thickness on the active layer side of In
_0.48(Ga _1-x1Al_x1)_0.52Made of P, and has the first and second electrodes
The remaining thickness on the side is the In_0.48(Ga_1-x2Al_x2)_0.52P
The composition ratio x2 is x2 = 0 on the first and second electrode sides.
Continuously change from x2 = x1 to x2 = 0
The Gunn diode is characterized by

The invention according to claim 8 is a high concentration n-type GaA
a first semiconductor layer made of high-concentration n-type GaAs, an active layer made of low-concentration n-type GaAs, and a second semiconductor layer made of high-concentration n-type InGaAlP are sequentially stacked on a semiconductor substrate made of s, A first electrode having a small area and a second electrode having a large area for applying a voltage to the active layer are arranged on a second semiconductor layer, and at least the second semiconductor is provided around the first electrode. In the method of manufacturing a Gunn diode, wherein a recess is formed up to the lower surface of the layer, and the portions of the second semiconductor layer and the active layer corresponding to the first electrode are partitioned as a region functioning as a Gunn diode, the recess is , The second electrode using the first and second electrodes as a mask
The semiconductor layer is formed by selectively removing the semiconductor layer by etching.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a diagram showing the structure of a Gunn diode 10A according to a first embodiment of the present invention, in which (a) is a plan view and (b) is FIG. Figure 2
Is a manufacturing process diagram. The manufacturing process will be described according to the contents of FIG.

First, for example, MBE (Molecular Beam Epitaxial) is formed on a semiconductor substrate 11 made of high-concentration n-type GaAs.
By the method, a high-concentration n-type GaAs layer to be the first contact layer 12 was formed with an impurity concentration of 2 × 10 ¹⁸ atom / cm ³ and a thickness of 1 μm.
Grow to a degree. Furthermore, a low-concentration n-type GaAs active layer 13 (impurity concentration 1.2 × 10 ¹⁶ atom / cm ³ , thickness: about 1.7 μm), and a high-concentration n-type In _0.48 (Ga _1-x Al _x ) _0.52 P layer ( A second contact layer 14 having an impurity concentration of 2.0 × 10 ¹⁸ atom / cm ³ and a thickness of about 0.2 μm) is sequentially laminated. The composition ratio x of Al to Ga of the second contact layer 14 is changed toward the surface side so that the surface becomes x = 0. More specifically, the composition ratio x on the active layer 13 side is predetermined. Only the thickness becomes constant, and the remaining thickness may change continuously from the surface to the surface, or may change continuously or stepwise from the active layer 13 side to the surface side or in a mode in which they are arbitrarily combined. The part may include a part having a constant composition ratio x.

Next, AuGe / Ni / Au, which makes ohmic contact with the high-concentration n-type In _0.48 (Ga _1-x Al _x ) _0.52 P layer which is the second contact layer 14, is vapor-deposited, and the electrode pattern is formed by the lift-off method. To form. Then, heat treatment is performed to form a large area anode electrode 15 and a small area cathode electrode 16 ((a) of FIG. 2).

Here, since the composition of the In _0.48 (Ga _1-x Al _x ) _0.52 P layer changes toward the surface so that the surface has x = 0, the high concentration n-type In _0.48 Ga is formed on the outermost surface. _{It is 0.52} P, and ohmic contact with the cathode electrode 15 and the anode electrode 16 can be sufficiently obtained.

Next, the photoresist 17 is patterned so as to open a part of the surfaces of the anode electrode 15 and the cathode electrode 16, and the anode electrode 15 and the cathode electrode 1 are formed in the openings by electrolytic plating or electroless plating.
Using 6 as a base electrode, bumps (electrodes) 18 and 19 which are conductive protrusions made of Au or the like are deposited and formed on the upper surface ((b) of FIG. 2).

Next, the photoresist 17 is removed to expose the second contact layer 14, and then the anode electrode 15 and the cathode electrode 16 are used as a mask, and a mixed gas of CH ₄ , H ₂ and Ar is used. ECR dry etching using (JR Lothian et al., J. Electron. Mater.
Vol.21 No.4 441 (1992)), the exposed second contact layer 14 alone is selectively removed, and a substantially mesa-shaped or vertical recess 2 is formed around the cathode electrode 16.
0 is formed ((c) of FIG. 2). Thus, the target recess 20 can be accurately formed by the vertical etching by self-alignment using the upper anode electrode 15 and the cathode electrode 16 as a mask. Especially InGaAl
Since only the P second contact layer 14 can be selectively removed by etching, manufacturing variations are reduced and the yield is improved.

Here, the area of the active layer 13 corresponding to the cathode electrode 16 defined by the recess 20 (area of the cathode electrode 16) is an area (lateral cross-sectional area) where a predetermined operating current as a Gunn diode can be obtained. Is set to. That is, the area is set so that it can function as a Gunn diode. On the other hand, the area of the active layer 13 corresponding to the anode electrode 15 is made sufficiently larger than the area of the active layer 13 corresponding to the cathode electrode 16, so that the electric resistance of the semiconductor laminated portion below the anode electrode 15 is reduced to the semiconductor below the cathode electrode 16. By making it sufficiently smaller than the electric resistance of the laminated portion (Gun diode function portion), this portion does not function as a Gun diode but functions as a resistance having a substantially low value, and the anode electrode 15 is substantially directly connected to the first electrode. 1 to the contact layer 12.

If the area ratio of the region portion of the active layer 13 corresponding to the cathode electrode 16 is less than 10, the operation efficiency is only lowered and there is no effect, and it is necessary to be 10 or more. It is preferably about the following.

The recess 20 may be formed by selectively etching the second contact layer 14 made of InGaAlP using a hydrochloric acid / phosphoric acid mixed etchant (FIG. 2 (d)). ). Since the thickness of the second contact layer 14 is as thin as 0.2 μm, there is no variation in the target depth of the recess 20 despite the wet etching, and the recess 20 can be accurately formed. Further, the recess 20 may be formed so as to dig into the active layer 13 to some extent, or may be formed so as to dig into the first contact layer 12 to some extent after removing the active layer 13.

Then, the back surface of the semiconductor substrate 11 is polished and thinned so that the thickness of the entire Gunn diode is about 100 μm according to a normal Gunn diode manufacturing process. Then, if necessary, AuGe, Ni, Au, or T that makes ohmic contact with the semiconductor substrate 11 is provided on the back surface of the semiconductor substrate 11.
A metal film 21 made of i, Pt, or the like is deposited and heat treatment (annealing) is performed ((d) of FIG. 2). The metal film 21 formed on the back surface of the semiconductor substrate 11 is not necessarily required, but can function as an anode electrode instead of or together with the anode electrode 15. At this time, the anode electrode 15
It is possible to further reduce the electric resistance of the semiconductor laminated portion below the.
At this time, the anode electrode 15 is replaced by the cathode electrode 16
Since it is on the same surface as, it can function as a spacer at the time of mounting.

As described above, in the Gunn diode 10A of this embodiment, the recess 20 is formed in the semiconductor laminated portion so as to surround the cathode electrode 16 having a small area.
Gunn diode function part (region part corresponding to cathode electrode 16 in active layer 13 and second contact layer 14)
And a low resistance layer portion that functions as an external voltage application path to the first contact layer 12 of the Gunn diode function portion, the second contact layer 14
Both electrodes of the anode electrode 15 and the cathode electrode 16 can be provided on the upper surface of the. That is, the anode electrode 15 and the cathode electrode 16 can be put together on the same surface. Therefore, it has great advantages in terms of mounting and heat dissipation.

Further, only the second contact layer 14 is self-aligned by etching for defining a region (the Gunn diode function portion) that determines the operating current, using the electrodes 15 and 16 formed on the upper portion of the region as a mask. Since it is selectively removed, the manufacturing variation is smaller and the yield can be increased as compared with the conventional chemical wet etching.

FIG. 5 shows the energy of the Gunn diode shown in FIG.
The Gieband diagram is shown. As shown in the figure, the cathode electrode 1
6 is n-type high concentration In_0.48(Ga_1-xAl_x)_0.52Second P layer
The n-type low concentration GaAs layer is formed through the contact layer 14.
Connected to the active layer 13. Here, n-type high concentration In
_0.48(Ga_1-xAl_x)_0.52P second contact layer 14 and n-type
The active layer 13 which is a low concentration GaAs layer forms a heterojunction
However, a band discontinuity of the conduction band is formed. The height of this barrier
That is, the discontinuity ΔEc of the conduction band is the Al composition ratio x
Is set by appropriately selecting. Barrier height qV
Is ΔEc or In _0.48(Ga_1-xAl_x)_0.52P layer, GaAs layer
It can be set by appropriately selecting the impurity concentration. Ingredient
Physically, the conduction band discontinuity ΔEc is 0.19 eV ~ 0.30
Set to eV. As a result, it is injected into the active layer 13.
Conducted electrons become hot electrons and become gamma
It is possible to make a transition to the L valley, which has a higher energy band than Leh
You have as much energy as you can
It is possible to suppress the occurrence of burnout to a minimum.

In FIG. 5, the second contact layer 14
_Has a predetermined thickness on the active layer 13 side of In _0.48 (Ga _1-x1 A
The composition ratio x1 of Al to Ga is constant at l _x1 ) _0.52 P, but the remaining thickness portion on the electrodes 15 and 16 side is In _0.48 (Ga
_1-x2 Al _x2 ) _0.52 P, the compositional ratio x2 of Al to Ga continuously changed. That is, the electrode 15,
The composition ratio x2 of Al to Ga on the 16 side is x2 = x
It continuously changes from 1 to x2 = 0.

FIG. 6 shows the conduction band discontinuity ΔEc and In _0.48.
(Ga _1-x Al _x ) _0.52 shows the relationship with the Al composition ratio x of the P layer (M
iyako O et al., Appl.Phys.Lett.Vol.50 No.14 906 (198
7)). As shown in the figure, by controlling the Al composition ratio x in the range of 0 to 0.4, the band discontinuity ΔEc of the conduction band is 0.19 e.
It can be controlled from V to 0.30 eV. The reason why the upper limit of the conduction band discontinuity ΔEc is set to 0.30 eV is that when it exceeds 0.30 eV, the number of electrons that can get over the barrier decreases and the oscillation efficiency decreases. Also, the conduction band discontinuity Δ
The lower limit of Ec is set to 0.19 eV because if it is less than that, the transition between valleys becomes slow, the dead zone increases, and the oscillation efficiency decreases.

In the above, the cathode electrode 16 and the bump 19 are formed.
Although only one concave portion 20 is formed in the central portion, a plurality of concave portions 20 may be formed between the bumps 18 on both sides in a matrix shape, a zigzag shape, a radial shape, a ring shape, or another arrangement shape. By doing so, the mesa structure portion functioning as a Gunn diode is dispersed in a plurality of places, so that the heat dissipation efficiency is remarkably improved, and the oscillation efficiency and the oscillation power can be greatly improved.

FIG. 3 shows the Gunn diode 1 of the first embodiment.
It is a figure which shows the cross section of the Gunn diode 10B of the modification of 0A. In this embodiment, the acceleration energy is 30 Ke as a pre-process of the process of FIG. 2D of the first embodiment described above.
V, 100KeV, 200KeV, each dose amount 7 × 1
Boron (B) is ion-implanted from above the recess 20 a total of three times under the conditions of 0 ¹² / cm ² , 1 × 10 ¹³ / cm ² , and 2 × 10 ¹³ / cm ² , and heat treatment at 400 ° C. The high resistance layer 22 is formed on the active layer 13 from the upper portion to the lower portion thereof. The other steps were the same as those described in FIG. The resistance value of the high resistance layer 22 is sufficient so that current concentration does not occur in the recess 20 and may be equal to or higher than the resistance value of the active layer 13, but is 0.1 Ω · cm or more. preferable. In addition to boron (B), oxygen (O), iron (Fe), hydrogen (H), or the like can be used as the implanted ions.

[Second Embodiment] FIG. 4 is a view showing a cross section of a Gunn diode 10C according to a second embodiment. In this embodiment, a high resistance layer 23 having a high resistance is formed on the second contact layer 14 by an ion implantation method similar to the high resistance layer 22 shown in FIG. 3, and the special recess 20 is not formed. It is a thing. Except for the high resistance layer 23, it is the same as the Gunn diodes 10A and 10B of the embodiment of FIG. 1 and FIG. 2 and has the same function and effect.

[Summary of First and Second Embodiments] The Gunn diode of the present invention formed as described above is an n-type Ga
In forming the As active layer 13 and the n-type contact layer 14
_0.48 (Ga _1-x Al _x ) _{0.52 Between the} P layer and the Al composition ratio x is 0.4
In the case of, the conduction band discontinuity ΔEc is 0.30 eV, so that G from the cathode electrode 16 through the contact layer 14
The electrons injected into the aAs active layer 13 have a large energy at least by the energy corresponding to the conduction band discontinuity ΔEc. Therefore, the active layer 1
The conduction electrons injected into 3 can easily transit from the gamma valley to the L valley having a large energy state, and the occurrence of a dead zone can be suppressed to the minimum. n-type GaAs active layer 13 and second contact layer 1
The band discontinuity ΔEc of the conduction band between the In _0.48 (Ga _1-x Al _x ) _0.52 P layer that constitutes _No. 4 is determined by the Al composition ratio x, but in the MBE method described above, the Al composition ratio x Since it is possible to grow the semiconductor film while controlling accurately, the Gunn diode capable of accurately controlling the conduction band discontinuity ΔEc with good reproducibility can be formed.

[Third Embodiment] FIG. 7 shows an example of a structure in which the Gunn diode 10 (10A, 10B, 10C) is mounted on a plate circuit board forming a microstrip line 30 to form an oscillator. . Aluminum nitride (AlN), silicon (Si), silicon carbide (SiC), diamond, etc. have a specific resistance of 10 ⁶ Ω · c
A signal electrode 32 is formed on a semi-insulating flat plate substrate 31 having a thermal conductivity of 140 W / mK or more and a ground electrode 33 on the back surface. Reference numeral 34 denotes a via hole filled with tungsten, which connects the ground electrode 33 on the back surface to the surface ground electrode 35 formed on the surface. The bump 19 of the cathode electrode 16 of the gun diode 10 is the signal electrode 3
The bumps 18 on both sides of the anode electrode 15 are bonded to the ground electrodes 34 on both sides. 32A is an electrode of a bias section for supplying a power supply voltage to the Gunn diode 10,
Reference numeral 32B is an electrode forming a resonator by a microstrip line including the Gunn diode 10, and 32C is an electrode of a signal output portion by the microstrip line.

An oscillator constructed by mounting the Gunn diode 10 in this way has an oscillation frequency of 60 GHz and an oscillation frequency of 60 m when the electrode 32B as a resonator has a length of 520 μm.
The oscillation output of W is obtained.

In this mounting structure, the gun diode 10 is placed face down and the bumps 18 and 19 are connected to the electrode 3
Since it is directly connected to Nos. 5 and 32 and a gold ribbon is not used, the generation of parasitic inductance caused by the connection with the gold ribbon is eliminated, and it is possible to realize an oscillator with less variation in characteristics.

Further, since the heat generated in the Gunn diode 10 is dissipated to the substrate 31 which also functions as a heat sink via the bumps 18 and 19, the heat dissipation effect is enhanced. Furthermore, in such a mounted state of the Gunn diode 10,
The anode electrode 1 is provided on both sides of the bump 19 of the cathode electrode 16.
Since the bumps 18 of No. 5 are located, it is possible to prevent an excessive load from being applied to the cathode electrode 16.

[0048]

As described above, according to the present invention, a region functioning as a Gunn diode is formed by using the anode electrode and the cathode electrode formed above the region as a mask.
Since the second semiconductor layer of nGaAlP can be defined by selective etching, or a high resistance layer can be formed by ion implantation using the same mask, it is possible to reduce characteristic variations of the Gunn diode.

In addition, the GaAs active layer and InGaAlP
By utilizing the band discontinuity in the conduction band of the heterojunction of the second semiconductor layer, it is possible to inject conduction electrons having high energy into the active layer, so that the occurrence of a dead zone is suppressed to a minimum. Therefore, the power consumption of the Gunn diode can be reduced. The conduction band discontinuity of the heterojunction can be formed with good reproducibility by easily controlling the composition of the compound semiconductor forming the semiconductor layer and the like by utilizing the MBE method or the like.

In the Gunn diode of the present invention, since the bumps of the cathode electrode and the anode electrode can be provided on the same surface at the same level of height, they can be mounted face down. For this reason, it is not necessary to assemble into a pill type package as in the conventional case, and it is possible to easily assemble onto a flat board, which is a great advantage in assembling.

Further, since it is not necessary to connect the minute electrodes with a gold ribbon or the like at the time of mounting, parasitic inductance is not generated, and variations in circuit characteristics due to variations in the length of the gold ribbon can be eliminated.

Further, by arranging the mesa structure portion substantially functioning as a Gunn diode as a plurality of parts, the heat dissipation efficiency is remarkably improved, and the oscillation efficiency and the oscillation power can be greatly improved. .

[Brief description of drawings]

FIG. 1 is a diagram showing a Gunn diode according to a first embodiment of the present invention, in which (a) is a plan view and (b) is a sectional view.

FIG. 2 is a diagram illustrating a method of manufacturing the Gunn diode of FIG.

FIG. 3 is a sectional view of a Gunn diode which is a modified example of the Gunn diode of FIG.

FIG. 4 is a sectional view of a Gunn diode according to a second embodiment.

FIG. 5 is an energy band diagram illustrating an embodiment of the present invention.

FIG. 6 Δ of In _0.48 (Ga _1-x Al _x ) _0.52 P layer / GaAs layer
It is a figure which shows the dependency of Al composition ratio x of Ec.

FIG. 7 is a perspective view of a mounting structure according to a third embodiment.

FIG. 8 is a cross-sectional view of a conventional Gunn diode.

FIG. 9 is a sectional view of another conventional Gunn diode.

FIG. 10 is a cross-sectional view of the Gunn diode of FIGS. 8 and 9 incorporated in a pill-type package.

[Explanation of symbols]

10, 10A, 10B, 10C: Gunn diode 11: semiconductor substrate, 12: first contact layer, 13:
Active layer, 14: second contact layer, 15: anode electrode, 16: cathode electrode, 17: photoresist, 18,
19: bump, 20: concave portion, 21: metal film, 22, 2
3: high resistance layer 30: microstrip line, 31: flat substrate, 3
2: signal electrode, 33: ground electrode, 34: via hole,
35: surface ground electrodes 100A, 100B: conventional Gunn diode, 101:
Semiconductor substrate, 102: first contact layer, 103: active layer, 104: second contact layer, 105: cathode electrode, 106: anode electrode 110: pill type package, 111: heat dissipation base electrode, 1
12: Cylinder, 113: Gold ribbon, 114: Metal disk

Claims (8)

[Claims] 1. A semiconductor substrate made of high-concentration n-type GaAs, a first semiconductor layer made of high-concentration n-type GaAs, an active layer made of low-concentration n-type GaAs, and high-concentration n-type InG.
A Gunn diode in which a second semiconductor layer made of aAlP is sequentially stacked, the first diode having a small area and a large area for applying a voltage to the active layer, the first electrode being arranged on the second semiconductor layer. The second electrode and the portion of the second semiconductor layer and the active layer which are cut from the periphery of the first electrode to at least the lower surface of the second semiconductor layer and correspond to the first electrode are formed by a gun. A gun diode, comprising: a recess that defines a region to function as a diode. 2. A first semiconductor layer made of high concentration n type GaAs, an active layer made of low concentration n type GaAs, and high concentration n type InG on a semiconductor substrate made of high concentration n type GaAs.
A Gunn diode in which a second semiconductor layer made of aAlP is sequentially stacked, the first diode having a small area and a large area for applying a voltage to the active layer, the first electrode being arranged on the second semiconductor layer. A second electrode and a portion of the second semiconductor layer and the active layer which are formed by ion implantation from the periphery of the first electrode to at least the lower surface of the second semiconductor layer and correspond to the first electrode. And a high resistance layer that divides the region as a region that functions as a Gunn diode. 3. The Gunn diode according to claim 1, wherein the second semiconductor layer and the active layer include a film having a conduction band discontinuity of 0.19 eV to 0.30 eV. 4. The composition of InGaAlP of the second semiconductor layer according to claim 1, wherein the composition of InGaAlP is In _0.48.
(Ga _1-x Al _x ) _0.52 P, which is lattice-matched with the active layer. 5. The composition ratio x of Al of In _0.48 (Ga _1-x Al _x ) _0.52 P of the second semiconductor layer according to claim 4, wherein x = 0 to 0.4. Gunn diode. 6. The In _0.48 (Ga _1-x Al _x ) _0.52 P of the second semiconductor layer according to claim 4 or 5, wherein x = 0 on the first and second electrode sides. A Gunn diode characterized in that the composition changes toward the first and second electrodes. 7. The In _0.48 (Ga _1-x Al _x ) _0.52 P of the second semiconductor layer according to claim 4 or 5, wherein a predetermined thickness portion on the active layer side is In _0.48 (Ga _{1- x1} Al _x1 ) _0.52
P, the remaining thickness of the first and second electrode sides is In _0.48 (Ga _1-x2 Al _x2 ) _0.52 P, and the composition ratio x2 is x2 on the first and second electrode sides. X2 = x so that
A Gunn diode characterized by continuously changing from 1 to x2 = 0. 8. A first semiconductor layer made of high concentration n type GaAs, an active layer made of low concentration n type GaAs, and high concentration n type InG on a semiconductor substrate made of high concentration n type GaAs.
A second semiconductor layer made of aAlP is sequentially stacked, and the second semiconductor layer is formed.
A first electrode having a small area for applying a voltage to the active layer and a second electrode having a large area are arranged on the semiconductor layer, and at least a portion of the second semiconductor layer is provided around the first electrode. In the method of manufacturing a Gunn diode, wherein a recess is formed up to the lower surface, and the portions of the second semiconductor layer and the active layer corresponding to the first electrode are partitioned as a region that functions as a Gunn diode. Using the first and second electrodes as a mask,
A method of manufacturing a Gunn diode, which is formed by selectively removing the second semiconductor layer by etching.