JP2003045900A - Nitride based iii-v compound semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nitride based III-V compound semiconductor device capable of being manufactured while keeping a growth temperature fixed. SOLUTION: The nitride based III-V compound semiconductor device is manufactured by using a nitride based III-V compound semiconductor containing gadolinium(Gd). For instance, GaGdN manufactured by adding Gd to GaN can be grown at the same temperature as GaN or AlGaN and a band gap is reduced more than GaN. Thus, in the case of manufacturing a heterojunction field-effect transistor, a light emitting diode or a laser diode or the like by using GaN and AlGaN, by using GaGdN containing Gd, a crystal is grown in the state of keeping a substrate temperature fixed, and the nitride based III-V compound semiconductor device is manufactured without lowering the performance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a nitride system III-V.
TECHNICAL FIELD The present invention relates to a group III compound semiconductor device, and more particularly, to a nitride III-V compound semiconductor device manufactured by keeping a growth temperature constant by arbitrarily changing a lattice constant and a band gap by containing a specific element. .

[0002]

2. Description of the Related Art AlN, GaN and InN are the only known binary nitride III-V compound semiconductors, and these binary nitride III-V compound semiconductors have a wurtzite structure. It is known. Conventional nitride system
The III-V compound semiconductor device includes AlN, GaN,
It is manufactured by arbitrarily combining InN and these mixed crystal semiconductors.

The nitride-based III-V group compound semiconductor device is described, for example, in Jan. J. Appl. Phys
Vol 137 (1998) pp. L309-L312
Laser diode (LD; Laser Diode)
Is disclosed. In the above-mentioned prior art, InGaN, which is a nitride-based III-V group compound semiconductor containing In having a small band gap, is used in the active layer of the laser diode. In addition, a light emitting diode (LED; Light)
Since the Emitting Diode can be realized with the same structure as the laser diode, the light emitting diode can be manufactured by using InGaN for the light emitting layer.

US Pat. No. 519
2987 and Proc. Int. Workshop
on Nitride Semiconductors
IPAP Conf Series lpp. 233
-236 includes a heterojunction field effect transistor (H
FET; Hetero Field EffectTr
disclosed). Proc. In
t. Workshop on Nitride Sem
iconductors IPAP Conf Ser
ies lpp. In the heterojunction field effect transistor disclosed in 233-236, InN having high mobility is used for the channel layer.

[0005]

SUMMARY OF THE INVENTION For example, the above-mentioned 2
MBE (Mole
The optimum growth temperature for the AlN is 800 ° C. or higher.
It is around 700 ° C. for GaN and around 550 ° C. for InN.

When growing a ternary mixed crystal using these binary nitride III-V compound semiconductors, the crystal growth temperature is determined by the semiconductor having the lower optimum growth temperature. As a specific example, InGaN and GaN or AlGaN
And at least one of
A case of manufacturing a group compound semiconductor device will be described.

For example, a nitride-based III-V compound semiconductor device is used as a laser diode or a heterojunction field effect transistor. When InGaN having a smaller bandgap than GaN is produced as the active layer of the laser diode and the channel layer of the heterojunction field effect transistor, re-evaporation of In or dissociation of InN is severe if the growth conditions of InGaN and GaN are equal. Since it occurs, only GaN containing almost no In grows.
Therefore, to grow InGaN, it is necessary to use a growth temperature lower than that of GaN or AlGaN.

On the other hand, after growing InGaN at a low temperature,
When GaN or AlGaN is grown subsequently to InGaN, the growth temperature of GaN or AlGaN is set to In.
Since the temperature needs to be higher than the growth temperature of GaN, In
Re-evaporation of GaN or diffusion of In occurs, which deteriorates the quality of the active layer or the channel layer.

Therefore, it is difficult to manufacture a nitride III-V group compound semiconductor having a bandgap smaller than that of GaN at the same growth temperature as GaN or AlGaN.

An object of the present invention is to provide a nitride-based III-V group compound semiconductor device which can be manufactured while maintaining a constant growth temperature.

[0011]

SUMMARY OF THE INVENTION The present invention is a nitride III-V compound semiconductor device including a gadolinium-containing nitride III-V compound semiconductor device.

According to the present invention, by adding gadolinium (Gd) to the nitride-based III-V group compound semiconductor, for example, a nitride-based III-V group compound semiconductor having a band gap smaller than that of GaN is converted into GaN. Or Al
It can be produced at the same growth temperature as GaN. Therefore, it becomes possible to fabricate a nitride-based III-V group compound semiconductor device while keeping the substrate temperature constant.

The present invention is also characterized in that the nitride-based III-V group compound semiconductor device is a heterojunction field effect transistor.

According to the present invention, the present invention can be applied to a heterojunction field effect transistor as a nitride III-V group compound semiconductor.

Further, the present invention is characterized in that a nitride-based III-V group compound semiconductor containing gadolinium is used for the channel layer of the heterojunction field effect transistor.

According to the present invention, a nitride-based III-V containing Gd in the channel layer of a heterojunction field effect transistor.
Group compound semiconductor is used, for example, GaN or AlG
When a transistor is manufactured by a heterojunction with aN, a semiconductor heterojunction having a different band gap can be manufactured while the substrate temperature is kept constant. Therefore, it is possible to manufacture a heterojunction field effect transistor having excellent characteristics.

Further, the present invention is characterized in that the composition of Gd in the channel layer is more than 0% and 30% or less.

When the composition of Gd exceeds 30%, the rock salt structure, which is a stable crystal structure inherent to Gd, becomes dominant, so that the crystallinity of the wurtzite structure of the nitride III-V compound semiconductor deteriorates. . According to the present invention, the composition of Gd in the channel layer is more than 0% and 30% or less, that is, AlwGaxInYGdZN, W + X + Y + Z = 1,0.
By setting <Z ≦ 0.3, the crystallinity as a wurtzite structure can be maintained and good crystal growth can be achieved. Moreover, the characteristics of the heterojunction field effect transistor can be arbitrarily changed by changing the composition of Gd.

Further, in the present invention, GdN / AlxGa1-x is formed in the channel layer of the heterojunction field effect transistor.
It is characterized by using an N (0 ≦ X ≦ 1) superlattice structure.

According to the present invention, GdN / AlxGa1-xN is formed in the channel layer of the heterojunction field effect transistor.
(However, 0 ≦ X ≦ 1) A superlattice structure is used. Therefore, GdN / AlxGa1-xN (where 0 ≦ X ≦
1) The bandgap of the channel layer is changed from the value of GdN to GdN / by changing the thickness of each layer of the superlattice structure arbitrarily.
It is possible to arbitrarily change the value up to the value of AlxGa1-xN (where 0 ≦ X ≦ 1).

Further, the present invention is characterized in that the nitride III-V compound semiconductor device is a light emitting diode or a laser diode.

According to the present invention, it can be applied to a light emitting diode or a laser diode as a nitride III-V group compound semiconductor device.

The present invention is also characterized in that a nitride-based III-V group compound semiconductor containing Gd is used in the light emitting layer of the light emitting diode or the active layer of the laser diode.

According to the present invention, a nitride-based material containing Gd in the light emitting layer of a light emitting diode or the active layer of a laser diode.
By using a III-V group compound semiconductor, a series of crystal growth can be performed in a state where the substrate temperature is kept constant when joining with another nitride-based III-V group compound semiconductor.

Further, the present invention is characterized in that the composition of gadolinium in the light emitting layer or the active layer is more than 0% and 30% or less.

If the composition of Gd exceeds 30%, the rock salt structure, which is a stable crystal structure inherent in Gd, becomes dominant, and the crystallinity of the wurtzite structure of the nitride III-V compound semiconductor deteriorates. . According to the invention, the composition of Gd in the light emitting layer of the light emitting diode or the active layer of the laser diode is more than 0% and 30% or less, that is, AlwGa.
xInYGdZN, W + X + Y + Z = 1,0 <Z ≦ 0.
When it is 3, crystallinity as a wurtzite structure can be maintained and good crystal growth can be achieved. Also,
The characteristics of the light emitting diode or the laser diode can be arbitrarily changed by changing the composition of Gd.

In the present invention, the light emitting layer of the light emitting diode or the active layer of the laser diode is GdN / AlxG.
It is characterized by using an a1-xN (0 ≦ X ≦ 1) superlattice structure.

According to the invention, GdN / AlxGa is formed in the active layer of the light emitting diode or the laser diode.
By using a 1-xN (where 0 ≦ X ≦ 1) superlattice structure, the emission wavelength is changed from the wavelength determined by GdN to G
It is possible to arbitrarily change the wavelength up to the wavelength determined by dN / AlxGa1-xN (where 0 ≦ X ≦ 1).

Further, the present invention is characterized in that the nitride-based III-V group compound semiconductor device is an ultraviolet light absorption filter.

According to the invention, a nitride system III containing Gd
In the group-V compound semiconductor, ultraviolet absorption by the inner core electrons of Gd in the semiconductor occurs at a specific wavelength, and thus acts as a filter for specific ultraviolet rays.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION First, Ga is a nitride-based III-V group compound semiconductor containing Gd (gadminium).
The basic principle of the present invention will be described by taking as an example a method for producing GdN. Here, RF (Radio Frequency)
y) A nitride system III using a molecular beam epitaxy (hereinafter abbreviated as MBE) method using plasma-excited nitrogen.
A group-V compound semiconductor is manufactured, but for example, MOC
It is also possible to use the VD method or the like.

FIG. 1 is a diagram for explaining an example of producing GaGdN. Hereinafter, a method for manufacturing GaGdN shown in FIG. 1 will be described. Introduction (0001) Si surface SiC substrate 1 (hereinafter,
A SiC substrate 1) is heated to 850 ° C. in a vacuum chamber to remove surface oxidation of the substrate by hydrogen-nitrogen mixed plasma. Subsequently, the substrate temperature is set to 800 ° C. A
The 1N epitaxial buffer layer 2 is grown on the SiC substrate 1 to have a thickness of 20 nm. Then, the substrate temperature is set to 720 ° C. and the GaN epitaxial layer 3 is formed to a thickness of 25.
AlN epitaxial buffer layer 2 to have a thickness of 0 nm
Grow on. Then, the Ga beam intensity is set to 2.8 ×
10 ⁻⁷ Torr, Gd beam intensity 2.0 × 10 ⁻⁸ To
As rr, the GaGdN epitaxial layer 4 has a thickness of 25
GaN epitaxial buffer layer 3 to have a thickness of 0 nm
Grow up.

FIG. 2 is a diagram showing an X-diffraction pattern of GaGdN manufactured according to the above-described manufacturing method. S
GaN and GaGd based on the diffraction position of the iC substrate 1
When the lattice constants of N-axis C were calculated, the lattice constant of C-axis of GaN was c _Gan = 5.191Å and the lattice constant of C-axis of _GaGdN was c _GaGdN = 5.209Å. On the other hand, GaN
Has a bulk lattice constant of 5.185Å. Therefore, it is understood that GaN is pulled by the SiC substrate 1 and is subjected to compressive strain in the a-axis direction, and as a result, the lattice constant in the c-axis direction is larger than that in the bulk. In addition, (11-
24) Obtaining the lattice constants of GaN and GaGdN in the a-axis direction from asymmetric measurements, the lattice constant of GaN in the a-axis direction is a _GaN = 3.177Å, and the lattice constant of GaGdN in the a-axis direction is a _{GaG dN} = 3. It was 195Å.

Next, XPS (X-ray Photoe)
When the composition of the GaGdN epitaxial layer 4 described above was determined by electron spectroscopy measurement, the Gd composition was about 6%. From this, when the lattice constant of GdN under the compressive strain is calculated, G
lattice constant of c-axis direction of the aN is the lattice constant of c _GaN = 5.491Å, also a shaft was a _GdN = 3.477Å.

FIG. 3 shows the cathode luminescence (CL; Cathode) of the GaGdN epitaxial layer 4.
It is a figure which shows a Luminescence) spectrum. When the band gap of GaGdN was calculated from the CL spectrum shown in FIG. 3, the value was 3.35 eV.
Since the band gap of GaN is 3.4 eV, Gd
It has been clarified that the inclusion of the inclusions causes a narrow band gap.

As described above, even at the same growth temperature of 720 ° C. as that of GaN, Gd is taken into the GaN layer and Ga
The formation of GdN and the inclusion of Gd result in a narrow bandgap. When In is added to GaN under the same conditions, In is not incorporated into GaN, and the composition of the grown layer is almost the same as that of GaN, so narrow bandgap is impossible. Therefore, a semiconductor having a smaller band gap than GaN can be manufactured.
In addition, here, the G of the GaGdN epitaxial layer 4 is
It is shown that the d composition is 6%, but the Gd composition is 0%.
Is larger than 30% and is effective.

In the following examples, the nitride system III containing Gd was used.
A nitride III-V compound semiconductor device having a -V compound semiconductor will be specifically described.

(Embodiment 1) FIG. 4 is a heterojunction field effect transistor (HTFT) 5 according to Embodiment 1 of the present invention.
It is a figure which shows the structure of. The heterojunction field effect transistor is a transistor having a high electron mobility using a two-dimensional electron gas (2DEG) formed at the heterojunction interface as a carrier. The crystal growth method used in the fabrication of the heterojunction field effect transistor 5 of the present embodiment is the RF-MBE method, but MOCVD (Metal Organic Ch
Other crystal growth methods such as an electronic vapor deposition method may be used.

A method of manufacturing the heterojunction field effect transistor 5 will be described below. First, semi-insulating (0001)
Si surface SiC substrate 11 (hereinafter referred to as SiC substrate 11)
Is heated to 850 ° C. in a vacuum chamber to remove the surface oxide film on the substrate by hydrogen-nitrogen mixed RF plasma.
Then, the substrate temperature is set to 800 ° C. and the AlN epitaxial buffer layer 12 is grown on the SiC substrate 11 to have a layer thickness of 2 nm. Next, the substrate temperature is set to 720 ° C., and the GaN buffer layer 13 and the Ga _0.9 Gd _0.1 N channel layer 1 are formed on the AlN epitaxial buffer layer 12.
Sequentially grow to 4 and 50 nm. After that, the AlGaN barrier layer 1 is formed by photolithography.
A source / drain electrode 16 made of Ti / Al and a gate electrode 17 made of Au / Ni are formed on the surface of 5.

The maximum oscillation frequency of the above-mentioned heterojunction field effect transistor 5 was 250 GHz. On the other hand, instead of Ga _0.9 Gd _0.1 N channel 14, InGaN
The maximum oscillating frequency was 180 GHz in the heterojunction field-effect transistor grown under the same conditions as in the above-described manufacturing method using as a channel layer. INGaN to GaN
When grown at the same high temperature as above, the channel layer was close to the GaN layer, and the characteristics were almost the same as when the GaN layer was used as the channel. Therefore, the Ga _0.9 Gd _0.1 N channel layer 14 having a smaller band gap than GaN can be grown at the same temperature as the GaN buffer layer 12 and the Al _0.2 Ga _0.8 N barrier layer 15, and a transistor having excellent characteristics is manufactured. It becomes possible. Further, it is effective that the composition of Gd in the channel layer is larger than 0% and 30% or less.

(Embodiment 2) FIG. 5 is a diagram showing the structure of a heterojunction field effect transistor 6 which is Embodiment 2 of the present invention. The heterojunction field effect transistor 6 is the G of the heterojunction field effect transistor 5 of the first embodiment.
a _0.9 Gd _0.1 N In place of the channel layer 14, GdN / Alx
Ga1-xN (0≤X≤1) superlattice structure is used,
In this embodiment, X = 0 is used and the GdN / GaN superlattice 18 is used as the channel layer. The GdN / GaN superlattice 18 is used as a channel layer. GdN / GaN superlattice structure 1
8 is configured by laminating a GaN layer having a thickness of 10 nm and a GdN layer having a thickness of 2 nm, and the number of laminated GaN layers and GdN layers is 20. 5, the same parts as those of the heterojunction field effect transistor 5 of FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. The GdN / GaN superlattice 18 is
aN buffer layer 13 and Al _0.2 Ga _0.8 N barrier layer 1
Similar to No. 5, it is formed at a substrate temperature of 720 ° C.

The heterojunction field effect transistor 6
Had a maximum oscillation frequency of 300 GHz. Usually Gd
N has a rock-salt structure, but the layer thickness is thin and GaN
When sandwiched between layers, GaN can have a wurtzite structure. GdN having a rock salt structure has a band gap of about 2 eV. Estimated from the CL spectrum of the mixed crystal, which is 2 eV or more, the GdN of the wurtzite structure
The band gap of is also close to the band gap of GdN having a rock salt structure. On the other hand, the band gap of GaN is 3.
It is 4 eV. Therefore, the GdN / GaN superlattice 18 has a smaller bandgap than GaN.
It is thought that the career is flowing in.

As described above, GdN / Ga is formed in the channel layer.
By using the N superlattice 18, a heterojunction field effect transistor having more excellent characteristics can be manufactured.

In this embodiment, the channel layer is GdN /
AlxGa1-xN (0≤X≤1) X = 0 in superlattice structure
In this case, the GdN / GaN superlattice 18 is used, but the bandgap value can be arbitrarily changed by changing X, and a heterojunction field effect transistor having arbitrary characteristics is manufactured. It is possible to

(Third Embodiment) FIG. 6 is a diagram showing the structure of a laser diode (LD) 7 according to a third embodiment of the present invention. The crystal growth method used to manufacture the laser diode 7 is MOCVD, but RF-
Other crystal growth methods such as MBE method and MOCVD method may be used.

A method of manufacturing the laser diode 7 will be described below. First, the sapphire c-plane substrate 21 (hereinafter referred to as the sapphire substrate 21) is heated to 1100 ° C. and cleaned in a hydrogen atmosphere. Then, the substrate temperature is 550 ° C.
Then, the AlN buffer layer 22 is grown on the sapphire substrate 21 to have a layer thickness of 20 nm. Next, the substrate temperature is raised to 1000 ° C., and the n-GaN layers 23, n
-Al _0.2 Ga _0.8 N barrier layer 24, Ga _0.7 Gd _0.3 N active layer 25, p-Al _0.2 Ga _0.8 N barrier layer 26, and p-
The GaN gap layer 27 has a thickness of 1 μm,
Sequentially grow to have a thickness of μm, 0.4 μm, and 20 nm. Then, after forming a resonator by etching, the p electrode 28 and the n electrode 29 are formed on the p-GaN gap layer 17 and the GaN layer 23, respectively.

The threshold current density at room temperature of the laser diode manufactured as described above was 0.2 kA / cm ² . On the other hand, in order to form the InGaN layer in place of the Ga _0.7 Gd _0.3 N active layer 25, when the In composition is adjusted to have the same oscillation wavelength and the growth is performed under the same conditions as in the above-described manufacturing method, the threshold current In the case of GaN, the density and the oscillation wavelength were almost the same, and no In incorporation was observed. Therefore, the Ga _0.7 Gd _0.3 N active layer 25 having a smaller band gap than GaN is formed on the n-GaN layer.
Layer 23, n-Al _0.2 Ga _0.8 N barrier layer 24, p-Al
Since it can be grown at the same temperature as the _0.2 Ga _0.8 N barrier layer 26 and the p-GaN gap layer 27, a laser diode having excellent characteristics can be manufactured. Further, although the sapphire substrate is used as the substrate in this embodiment, a SiC substrate may be used instead. Further, it is effective that the composition of Gd in the channel layer is larger than 0% and 30% or less.

Further, the laser diode 7 shown in FIG.
Light emitting diode (LED; Light Emit)
toning diode). Crystal growth temperature
Is similar to the laser diode 7. With light emitting diode
Is the Ga of the laser diode _0.7Gd_0.3N active layer 25
It becomes a light emitting layer. In the light emitting diode with such a structure
Ga_0.7Gd_0.3When N is used for the light emitting layer, it is GaN
Blue-green light emission shifted to the longer wavelength side was obtained. one
On the other hand, InGaN is produced in the light emitting layer at the same crystal growth temperature.
In this case, the light emission is the same as when GaN is used for the light emitting layer.
I couldn't see it. Since this is grown at high temperature, InG
The aN active layer was not formed and was almost GaN.
It is thought that the cause is.

(Embodiment 4) FIG. 7 is a diagram showing a structure of a light emitting diode 8 and a laser diode 9 which are Embodiment 4 of the present invention. The light emitting layer or the active layer of the light emitting diode and the laser diode of the third embodiment is GaGdN, but in the light emitting diode 8 and the laser diode 9 of the present embodiment, the active layer is GdN / AlxGa1-xN.
A (0 ≦ X ≦ 1) superlattice structure is used, and in this embodiment, GdN / GaN superlattice 30 is used with X = 0.
Further, in FIG. 7, the same parts as those of the laser diode 7 of FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted. The crystal growth method used for manufacturing the light emitting diode 8 or the laser diode 9 of the present embodiment is MOCVD, but RF-MBE or ECR (Ele (Ele) using nitrogen radicals is used.
ctron Cyclotron Resonance
e) -MBE method may be used. Further, although the sapphire substrate 21 is used similarly to the light emitting diode and the laser diode of the third embodiment, a SiC substrate may be used instead.

The GdN / GaN superlattice 30 has a thickness of 10 n.
The GaN layer of m and the GdN layer of X nm in thickness were laminated. The number of stacked GaN layers and GdN layers was 20.

FIG. 8 shows the Gd of the GdN / GaN superlattice 30.
It is a figure which shows the light emission energy of the light emitting diode 8 and the laser diode 9 when changing the layer thickness of N layer.
As described above, the GdN / GaN superlattice 30 is used for the light emitting diode 8 and the laser diode 9, and the emission (oscillation) wavelength can be changed by changing the ratio of the GdN layer and the GaN layer.

When an InN / GaN superlattice is used for the active layer instead of the GdN / GaN superlattice 30, it is difficult to grow a crystal at a constant substrate temperature.
Good light emitting diodes and laser diodes can be obtained by using N. In this embodiment, the channel layer has a GdN / AlxGa1-xN (0 ≦ X ≦ 1) superlattice structure where X = 0.
However, the emission wavelength can be arbitrarily changed by changing the X, and a light emitting diode and a laser diode having an arbitrary emission wavelength can be manufactured.

(Embodiment 5) In this embodiment, nitrogen containing Gd is used.
Of ultraviolet light absorption using compound III-V compound semiconductor
Luther is explained. FIG. 9 shows Al containing Gd.
It is a figure which shows the CL spectrum of N. Refer to FIG.
And Gd in AlN near the wavelength of 320 nm ³⁺Due to
It has been confirmed that the luminescence is considered to be.

On the contrary, by using such a light emission characteristic, it becomes possible to absorb ultraviolet rays in the vicinity of 320 nm. That is, AlN containing Gd can be used as an ultraviolet light absorption filter. To shift the absorption wavelength to the longer wavelength side, for example, Ga may be added to AlN.

(Embodiment 6) In the method for manufacturing a semiconductor device of the present invention, an AlN layer is formed on a SiC substrate, and Ga is formed on the AlN layer.
An N layer is formed, and on top of that, a dilute magnetic semiconductor GaGdN layer based on a nitride semiconductor is used instead of AlGaN to form an RF plasma-assisted mole.
circular-beam epitaxy (RF-MB
It can be grown in E).

The composition of the GaGdN layer is, for example, Ga _0.94 G
Figure 1 shows an epitaxial film grown at d _0.06 N.
0 to 7K and FIG. 11 to 300K SQUID (su
perconducting quantum int
magnetic field measured using the surface device)
The magnetization characteristic (MH characteristic) is shown. In this measurement, the magnetic field is parallel to the sample.

In FIGS. 10 and 11, Gd and GaN having a rock salt structure have Curie temperatures of 307 K and 72 K, respectively.
Although it is a ferromagnetic substance having a magnetic field, a dilute magnetic semiconductor GaGdN ternary mixed crystal exhibits hysteresis characteristics in the temperature range of 7K to 300K. This is Ga _0.94 Gd _0.06
It is shown that the N ternary mixed crystal is ferromagnetic at both temperatures. (The saturation magnetic field strength at 300 K is 2 tesla and the coercive force is 70 oersted.) FIG. 12 shows the temperature dependence of the magnetization at a magnetic field strength of 0.1 tesla. The magnetization decreases slowly with temperature, but remains at 400K. This is G
This shows that the Curie temperature of a _0.94 Gd _0.06 N ternary mixed crystal is 400 K or higher, and that the Ga _0.94 Gd _0.06 N ternary mixed crystal based on a rare earth-added nitride semiconductor is ferromagnetic even at room temperature. Shows. Further in FIG.
The magnetization of Ga _0.94 Gd _0.06 N ternary mixed crystal is from 7K to 400K.
It continuously decreases with increasing temperature and no discontinuous change is observed. This result indicates that the ferromagnetic properties are not due to one magnetic phase without phase separation, that is, due to the formation of GaGdN ternary mixed crystal, rather than due to Gd and GdN.

Such ferromagnetic properties can be applied to an optical isolator, and since GaGdN itself emits light in the ultraviolet or blue region, it can be considered to be applied as an optical isolator in the ultraviolet / blue region. Alternatively, it becomes possible to realize a new active element (for example, a self-oscillation / optical isolating element) that combines the light emission characteristic and the magnetic characteristic of GaGdN itself.

[0059]

As described above, according to the present invention, by adding gadolinium (Gd) to a nitride III-V compound semiconductor, the substrate temperature is kept constant and the nitride III is used.
A -V compound semiconductor device can be manufactured.

According to the present invention, a nitride III-V containing Gd in the channel layer of a heterojunction field effect transistor.
Group compound semiconductor is used, for example, GaN or AlG
By manufacturing a transistor by a heterojunction with aN, it is possible to manufacture a heterojunction of semiconductors having different band gaps while keeping the substrate temperature constant, and thus it is possible to manufacture a heterojunction field effect transistor having excellent characteristics. Becomes

Further, according to the present invention, the composition of Gd in the channel layer of the heterojunction field effect transistor is 0%.
Greater than 30% or less, that is, AlwGa
xInYGdZN, W + X + Y + Z = 1,0 <Z ≦ 0.
When it is 3, crystallinity as a wurtzite structure can be maintained and good crystal growth can be achieved. Also,
The characteristics of the heterojunction field effect transistor can be arbitrarily changed by changing the composition of Gd.

Further, according to the present invention, GdN / AlxGa1- is formed in the channel layer of the heterojunction field effect transistor.
xN (where 0 ≦ X ≦ 1) superlattice structure is used, and the bandgap of the channel layer is changed from the value of GdN to GdN / AlxGa1-xN (where 0 ≦ X ≦ 1) by arbitrarily changing each layer thickness. Since the value can be changed arbitrarily, a transistor having arbitrary characteristics can be manufactured.

Further, according to the present invention, by using a nitride-based III-V group compound semiconductor containing Gd in the light emitting layer of the light emitting diode or the active layer of the laser diode, a series of films can be obtained while keeping the substrate temperature constant. Since the crystal can be grown, a light emitting diode or a laser diode having excellent characteristics can be manufactured.

According to the present invention, the composition of Gd in the light emitting layer of the light emitting diode or the active layer of the laser diode is more than 0% and 30% or less, that is, AlwGa.
xInYGdZN, W + X + Y + Z = 1,0 <Z ≦ 0.
When it is 3, crystallinity as a wurtzite structure can be maintained and good crystal growth can be achieved. Also,
The characteristics of the light emitting diode or the laser diode can be arbitrarily changed by changing the composition of Gd.

According to the present invention, GdN / AlxGa is formed in the active layer of the light emitting diode or the laser diode.
By using a 1-xN (where 0 ≦ X ≦ 1) superlattice structure, the emission wavelength is changed from the wavelength determined by GdN to G
It is possible to arbitrarily change the wavelength up to the wavelength determined by dN / AlxGa1-xN (where 0 ≦ X ≦ 1).

Further, according to the present invention, a nitride system containing Gd
By using the III-V group compound semiconductor in the wavelength converter, it becomes possible to fabricate a filter that absorbs specific ultraviolet rays.

Further, according to the present invention, by using a nitride III-V group compound semiconductor containing Gd for an optical isolator, it becomes possible to manufacture an optical isolator in the ultraviolet / blue region. Alternatively, a new active element (for example, a self-oscillation / optical isolating element) that combines the emission characteristics and magnetic characteristics of GaGdN itself.
Can be realized.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of manufacturing GaGdN.

FIG. 2 is a diagram showing an X-ray diffraction pattern of GaGdN.

FIG. 3 is a diagram showing a CL spectrum of GaGdN.

FIG. 4 is a diagram showing the structure of a heterojunction field effect transistor 5 that is Embodiment 1 of the present invention.

FIG. 5 is a diagram showing a structure of a heterojunction field effect transistor 6 which is Embodiment 2 of the present invention.

FIG. 6 is a diagram showing a structure of a laser diode 7 that is Embodiment 3 of the present invention.

FIG. 7 is a diagram showing a structure of a light emitting diode 8 and a laser diode 9 which are Embodiment 4 of the present invention.

FIG. 8 is a diagram showing the layer thickness dependence of the emission wavelengths of the light emitting diode 8 and the laser diode 9.

FIG. 9 is a diagram showing a CL spectrum of AlN added with Gd.

FIG. 10: Magnetic field at 7K measured using SQUID-
It is a figure which shows a magnetization characteristic (MH characteristic).

FIG. 11 is a diagram showing magnetic field-magnetization characteristics (MH characteristics) at 300K measured using SQUID.

FIG. 12 is a diagram showing temperature dependence of magnetization of GaGdN ternary mixed crystal.

[Explanation of symbols]

1, 11 Semi-insulating (0001) Si-face SiC substrate 2, 12 AlN epitaxial buffer layer 3, 13 GaN epitaxial buffer layer 4, 14 Ga _0.9 Gd _0.1 N channel layer 15 Al _0.2 Ga _0.8 N barrier layer 16 source electrode / drain Electrode 17 Gate electrode 18, 30 GdN / GaN superlattice 21 Sapphire c-plane substrate 22 AlN buffer layer 23 n-GaN layer 24 n-Al _0.2 Ga _0.8 N barrier layer 25 Ga _0.7 Gd _0.3 N active layer 26 p-Al _0.2 Ga _0.8 N barrier layer 27 p-GaN gap layer

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Claims (10)

[Claims] 1. A nitride-based III-V compound having a nitride-based III-V group compound semiconductor containing gadolinium.
Group V compound semiconductor device. 2. The nitride III-V compound semiconductor device according to claim 1, wherein the nitride III-V compound semiconductor device is a heterojunction field effect transistor. 3. The nitride III-V compound semiconductor device according to claim 2, wherein a nitride III-V compound semiconductor containing gadolinium is used for a channel layer of the heterojunction field effect transistor. . 4. The composition of Gd in the channel layer is more than 0% and 30% or less.
The nitride-based III-V compound semiconductor device described. 5. A GdN / AlxGa1-xN (0≤X≤1) is formed in a channel layer of the heterojunction field effect transistor.
3. The nitride-based III-V group compound semiconductor device according to claim 2, wherein a superlattice structure is used. 6. The nitride III-V compound semiconductor device according to claim 1, wherein the nitride III-V compound semiconductor device is a light emitting diode or a laser diode. 7. The nitride-based III-V group compound according to claim 6, wherein a nitride-based III-V group compound semiconductor containing Gd is used for the light-emitting layer of the light-emitting diode or the active layer of the laser diode. Semiconductor device. 8. The nitride-based III-V group compound semiconductor device according to claim 7, wherein the composition of gadolinium in the light emitting layer or the active layer is more than 0% and 30% or less. 9. The light emitting layer of the light emitting diode or the active layer of the laser diode is GdN / AlxGa1-xN (0
≦ X ≦ 1) The nitride-based III-V group compound semiconductor device according to claim 6, wherein a superlattice structure is used. 10. The nitride-based III-V group compound semiconductor device according to claim 1, wherein the nitride-based III-V group compound semiconductor device is an ultraviolet absorption filter.