JPH1187796A - Magnetic semiconductor device and magnetic recorder/ player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high sensitivity high response magnetic head. SOLUTION: A p-type GaAs layer 10 as a p-type emitter layer, an n-type Cabs layer 11 as an n-type base layer, a p-type magnetic semiconductor layer (Ing0.95 Mn0.05 As layer) 2 as a P-type collector layer, and a p-type GaAs layer 12 as a p-type emitter contact layer are formed sequentially. Subsequently, the p-type GaAs layer 10 is provided with a p-type ohmic electrode 13 as an emitter electrode, the n-type GaAs layer 11 is provided with an n-type ohmic electrode 14 as a base electrode and the p-type magnetic semiconductor layer 2 is provided with a p-type ohmic electrode 15 as a collector electrode thus obtaining a bipolar transistor structure being used as a magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic semiconductor device using a magnetic semiconductor layer and a magnetic recording / reproducing device.

[0002]

2. Description of the Related Art In recent years, the remarkable development of the electronics industry has been achieved by increasing the speed and integration of electronic devices, ie, LSIs such as CPUs and memories, and increasing the size of magnetic devices, such as magnetic disks, capable of recording enormous amounts of data. This is largely due to the development of magnetic recording media.

[0003] These electronic and magnetic devices are:
It can be said that they have developed independently while being influenced by each other. In the future, in order to meet the demands of the information society that requires higher speed and larger capacity, it is expected that electronic devices and magnetic devices will have higher performance,
Devices with new features that take advantage of both features are awaited.

Up to now, there have been reports of new concept devices such as spin transistors using magnetic metal, but there are still few such devices, and the semiconductor has a proactive property of controlling the carrier density from an external terminal. It can be said that there is no device used in the above.

In order to realize such a magnetic / electronic (semiconductor) device, a material which has a magnetic order while being a semiconductor is indispensable. Up to now, II-VI group compound semiconductors containing Mn or the like as a magnetic element have been known as candidates for such materials.

However, with such a material, p-type doping is difficult, and there is a difficulty in practical application. Recently, however, a group III-V semiconductor containing a small amount of Mn has been found to exhibit ferromagnetic order (H. Munekata et. Al Phy
s. Rev. LeH., 63, 1849, 1989).

In these materials, it is becoming clear that the magnetic order is affected by the carrier density.
Specifically, when the p-type carrier concentration is high, the ferromagnetic phase,
It is expected that when low, it will become a paramagnetic phase.

[0008] By utilizing these materials, there is a possibility that a device having a performance which cannot be achieved conventionally can be obtained. For example, when the inventors have studied, the conventional magnetic head has the following problems,
By using the above materials, a magnetic head capable of solving such a problem can be realized.

Conventionally, when performing magnetic recording, a magnetic field is generated by passing an electric current through a coil of a magnetic head to magnetize a core of the magnetic head. In order to realize a high-speed response of the magnetic head, it is desirable to reduce the number of turns of the coil as much as possible and to reduce the inductance.

However, when the number of turns of the coil is reduced, it becomes necessary to supply a large current to the coil in order to obtain a predetermined magnetic field. That is, a large current is required for writing. This imposes a burden on peripheral parts such as external circuits and the like, hinders miniaturization and leads to an increase in cost. When future ultra-large capacity recording and ultra-high-speed response are desired, this can be a big problem.

[0011]

As described above, devices having new functions utilizing both electronic (semiconductor) devices and magnetic devices have been awaited, but up to now, magnetic metals have been used. There have been reports of new concept elements such as spin transistors, but the number is still small, and there has been no device that actively utilizes the properties of semiconductors such as controlling the carrier density from external terminals.

The present invention has been made in view of the above circumstances, and has as its object to provide a novel magnetic semiconductor device based on the principle of magnetization by controlling the carrier density in a magnetic semiconductor layer. It is an object of the present invention to provide a magnetic semiconductor device that is effective for realizing a magnetic head that can be used or a magnetic head that can respond with high sensitivity and high speed.

[0013]

In order to achieve the above object, a magnetic semiconductor device according to the present invention (claim 1) is provided on a semiconductor substrate, and has a first magnetic field whose magnetic order changes according to the internal carrier density. A first semiconductor layer of conductivity type;
And a control electrode for changing the carrier density in the semiconductor layer and controlling the magnetic order of the first semiconductor layer.

According to the present invention, by using the first semiconductor layer as a magnetization layer and applying a voltage (magnetization signal) to the control electrode, the first semiconductor layer (hereinafter, referred to as a magnetic semiconductor layer) is provided.
Control the magnetic order of

When such a magnetic semiconductor layer is brought closer to a magnetic recording medium such as a magnetic tape or a magnetic disk, the magnetic order of the magnetic recording medium can be changed in accordance with the magnetic order of the magnetic semiconductor layer. Therefore, the magnetic semiconductor layer can be used as a recording core of a magnetic head.

Here, since the magnetic semiconductor layer does not need to use a coil for its magnetization, there is no inductance by the coil which hinders high-speed response. Therefore, according to the present invention, a semiconductor magnetic head capable of high-speed response can be realized.

A specific configuration of the present invention (claim 2) is to attach a Schottky electrode to the magnetic semiconductor layer. With such a configuration, a voltage (magnetization signal) is applied to the Schottky electrode to change the width of the depletion layer in the magnetic semiconductor layer, thereby causing the phase transition of the magnetic semiconductor layer from the paramagnetic state to the ferromagnetic state. Can be. Then, by bringing such a magnetic semiconductor layer closer to the magnetic recording medium, the magnetic state of the magnetic recording medium can be changed in accordance with the magnetic state of the magnetic semiconductor layer.

Here, in order to suppress the leak current,
Do not attach the Schottky electrode directly to the magnetic semiconductor layer,
It is preferable to attach a Schottky electrode to another semiconductor layer provided on the magnetic semiconductor layer and indirectly control the carrier density of the magnetic semiconductor layer.

Another specific configuration of the present invention (Claim 3)
Is a high-concentration p-type semiconductor layer (second semiconductor layer) / a low-concentration p-type
-Type magnetic semiconductor layer (magnetic semiconductor layer) / n-type semiconductor layer (third
Of the semiconductor layer) structure.

With such a configuration, the low-concentration p-type magnetic semiconductor layer is depleted at the time of 0 bias or reverse bias and becomes a paramagnetic state. At the time of forward bias, holes are injected and positive holes in the low-concentration p-type magnetic semiconductor layer are exposed. The pore concentration increases and a phase transition to a ferromagnetic state occurs. Then, by bringing such a magnetic semiconductor layer closer to the magnetic recording medium, the magnetic state of the magnetic recording medium can be changed in accordance with the magnetic state of the magnetic semiconductor layer.

Still another specific configuration of the present invention (claim 4) is a p-type semiconductor layer (fourth semiconductor layer) / n-type semiconductor layer (fifth semiconductor layer) / low-concentration p-type magnetic semiconductor Layer (first
Semiconductor layer) / high-concentration p-type semiconductor layer (sixth semiconductor layer)
A structure is formed, and each semiconductor layer is used as an emitter layer / base layer / collector layer / collector contact layer of a bipolar transistor.

With such a structure, when a reverse bias state is applied between the base and the collector, no signal is applied between the base and the emitter, and the collector (low-concentration p-type magnetic semiconductor layer) is formed. Holes are not injected into the layer, the collector (low-concentration p-type magnetic semiconductor layer) remains depleted, and enters a paramagnetic state.

On the other hand, when a signal enters between the base and the emitter, a large amount of holes are injected into the collector (low-concentration p-type magnetic semiconductor layer), and the phase transitions to a ferromagnetic state. When such a magnetic semiconductor layer is brought closer to the magnetic recording medium, magnetic information can be recorded by changing the magnetic state of the magnetic recording medium in accordance with the magnetic state of the magnetic semiconductor layer.

In this case, the magnetizing signal is given in the form of a base current, and the collector current, which is a large magnetizing current, can be controlled with a small current, so that the magnetic information recorded on the magnetic recording medium can be controlled. Can be obtained with high sensitivity. Further, since no coil is required, a semiconductor magnetic head capable of high-speed response can be obtained. Therefore, according to the present invention, it is possible to realize a semiconductor magnetic head capable of responding with high sensitivity and high speed.

The magnetic semiconductor layer is made of Ga, In.
And at least one group III element of Al and As, P
And at least one group V element of Sb III
It is preferable to use a group-V compound semiconductor as a base material and containing Mn as a magnetic impurity.

[0026]

Embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing a Schottky type semiconductor magnetic head according to a first embodiment of the present invention. This embodiment is an example in which the carrier density of a p-type magnetic semiconductor layer is controlled by a Schottky electrode.

In FIG. 1, reference numeral 1 denotes a p-type GaAs substrate (p-type impurity concentration: 5.times.16 ^cm.sup.-3 ).
A p-type magnetic semiconductor layer 2 is formed on the surface of the s substrate 1 by MBE.

This p-type magnetic semiconductor layer 2 is made of In _0.95 Mn.
_{It is made of 0.05} As, and its thickness and p-type carrier concentration are 50 nm and about 5 × 18 cm ⁻³ , respectively. The film forming temperature (epitaxial temperature) was 200 ° C.

A Schottky electrode 3 made of Al is formed on the p-type magnetic semiconductor layer 2 by a vapor deposition method. on the other hand,
On the back surface of the p-type GaAs substrate 1, a p-type ohmic electrode 4 made of AuZn is formed. This p-type ohmic electrode 4 is formed by forming an AuZn film by an evaporation method,
It is formed by performing a heat treatment at a temperature of one minute.

The voltages applied to the Schottky electrode 3 and the p-type ohmic contact electrode 4 are V3 and V4, respectively.
Then, when V3 <V4, the p-type magnetic semiconductor layer 2 is in a ferromagnetic state. However, when the Schottky barrier is in a reverse bias state, that is, when V3> V4, a part or the whole of the p-type magnetic semiconductor layer 2 is depleted, and the p-type magnetic semiconductor layer 2 becomes a paramagnetic state.

Therefore, a voltage is applied to the electrodes 3 and 4,
The magnetic state of the p-type magnetic semiconductor layer 2 can be controlled by changing the voltage between the electrodes 3 and 4 as described above, that is, by changing the carrier density in the p-type magnetic semiconductor layer 2.

When such a p-type magnetic semiconductor layer 2 is brought closer to a magnetic recording medium such as a magnetic tape or a magnetic disk, the magnetic state of the magnetic recording medium is adjusted in accordance with the magnetic state of the p-type magnetic semiconductor layer 2. Can be changed.

Here, since the p-type magnetic semiconductor layer 2 does not need to use a coil for its magnetization, there is no inductance due to the coil that hinders high-speed response. Therefore, according to the present embodiment, a semiconductor magnetic head capable of high-speed response can be realized. (Second Embodiment) FIG. 2 is a sectional view showing a Schottky type semiconductor magnetic head according to a second embodiment of the present invention. The parts corresponding to those of the semiconductor magnetic head of FIG. 1 are denoted by the same reference numerals as those of FIG. 1, and detailed description is omitted.

This embodiment is different from the first embodiment in that InGaP which is a non-magnetic semiconductor having a small number of recombination centers is provided between the p-type magnetic semiconductor layer 2 and the Schottky electrode 3.
InGaP intermediate layer 5 (thickness: 10 nm, p-type carrier concentration: about 1 × 16 cm ⁻³ ) is inserted.

The p-type magnetic semiconductor layer 2 has a low temperature (200 ° C.).
Because it was formed by epitaxial growth of
Not high in crystallinity. Therefore, when the Schottky electrode 3 is formed directly on the p-type magnetic semiconductor layer 2, there may be a case where characteristics such as an increase in leakage current due to recombination or the like occur.

Therefore, in the present embodiment, the Schottky electrode 3 is formed on the p-type magnetic semiconductor layer 2 via the InGaP intermediate layer 5 having a small number of recombination centers, thereby reducing the leak current. Like that.

In place of the InGaP intermediate layer 5, 4
A GaAs intermediate layer with high crystallinity obtained by epitaxially growing GaAs at a high temperature of 00 ° C. or higher may be used. Also,
The mechanism of magnetization of the p-type magnetic semiconductor layer 2 is the same as in the first embodiment, and will not be described. (Third Embodiment) FIG. 3 is a sectional view showing a pn diode type semiconductor magnetic head according to a third embodiment of the present invention. The portions corresponding to those of the semiconductor magnetic head of FIG. 1 are denoted by the same reference numerals as those of FIG.

In the first and second embodiments, the carrier density of the p-type magnetic semiconductor layer is controlled by a Schottky electrode.
It is an example in which the carrier density of the type magnetic semiconductor layer is controlled.

The semiconductor magnetic head of this embodiment will be described according to the manufacturing process. First, an n-type GaAs layer 6 (film thickness: 200 nm, n-type carrier concentration:
About 5 × 18 cm ⁻³ ), n-type GaAs layer 7 (film thickness: 200
nm, n-type carrier concentration: about 5 × 17 cm ⁻³ ), p-type magnetic semiconductor layer (In _0.95 Mn _0.05 As) layer 2 (film thickness: 10
0 nm, p-type carrier concentration: about 5 × 17 cm ⁻³ ), and a p-type GaAs layer 8 (film thickness: 50 nm, p-type carrier concentration: about 5 × 19 cm ⁻³ ) are sequentially formed by MBE.

Thereafter, a p-type ohmic electrode 4 is formed on the p-type GaAs layer 8, and an n-type ohmic electrode 9 is formed on the n-type GaAs layer 6, respectively. The n-type ohmic electrode 9 is made of AuGe
After a film is formed by an evaporation method, heat treatment is performed at 400 ° C. for one minute.

Here, the voltage applied to the p-type ohmic electrode 4 is Vp, and the voltage applied to the n-type ohmic electrode 9 is Vp.
Assuming that n, in the case of Vp <Vn, that is, in the reverse bias state, the p-type magnetic semiconductor layer 2 is depleted and enters the paramagnetic state.

The p-type GaAs layer 6 has a p-type carrier concentration of
It is sufficiently higher than the n-type carrier concentration of the n-type GaAs layer 7. For this reason, majority carriers of the pn diode are holes. Therefore, when Vp> Vn, that is, in the forward bias state, holes are injected into the p-type magnetic semiconductor layer 2 to be in a ferromagnetic state.

Therefore, a voltage is applied to the electrodes 4 and 9,
By changing the magnitude relationship between Vp and Vn as described above, that is, by changing the carrier density in the p-type magnetic semiconductor layer 2, the magnetic state of the p-type magnetic semiconductor layer 2 can be controlled.

When such a p-type magnetic semiconductor layer 2 is brought close to a magnetic recording medium such as a magnetic tape or a magnetic disk, the magnetic state of the magnetic recording medium is adjusted in accordance with the magnetic state of the p-type magnetic semiconductor layer 2. Can be changed.

Here, since the p-type magnetic semiconductor layer 2 does not need to use a coil for its magnetization, there is no inductance due to the coil that hinders high-speed response. Therefore, according to the present embodiment, a semiconductor magnetic head capable of high-speed response can be realized.

Since the pn junction of this embodiment is formed by using the epitaxial growth method (MBE method),
Compared to the Schottky junction formed using the evaporation method,
The crystallinity at the interface is good, the leak current is small, good characteristics are obtained, and the reliability is high.

FIG. 4 shows a band diagram of each semiconductor layer in an equilibrium state for reference. CB in FIG, VB, E _F respectively the conduction band, the valence band energy, indicating the Fermi energy. In the drawing, the hatched area indicates a neutral area. (Fourth Embodiment) FIG. 5 is a sectional view showing a bipolar transistor type semiconductor magnetic head according to a fourth embodiment of the present invention. The portions corresponding to those of the semiconductor magnetic head of FIG. 1 are denoted by the same reference numerals as those of FIG.

This embodiment is an example in which the bipolar transistor controls the carrier density of the p-type magnetic semiconductor layer. The semiconductor magnetic head of this embodiment will be described according to the manufacturing process. First, a p-type GaAs layer 10 (thickness: 500 nm, p-type carrier concentration: about 5 × 19 cm ⁻³ ) and an n-type GaAs layer 11 (film thickness:
300 nm, n-type carrier concentration: about 5 × 17 cm ⁻³ ),
p-type magnetic semiconductor layer (In _0.95 Mn _0.05 As layer) 2 (film thickness: 100 nm, p-type carrier concentration: about 5 × 17c)
m ⁻³ ) and a p-type GaAs layer 12 (thickness: 100 nm, p-type carrier concentration: about 2 × 19 cm ⁻³ ) are sequentially formed by MBE.

Thereafter, a p-type ohmic electrode 13 is formed on the p-type GaAs layer 10, an n-type ohmic electrode 14 is formed on the n-type GaAs layer 11, and a p-type ohmic electrode 15 is formed on the p-type GaAs layer 12.

These semiconductor layers 10, 11 and 12 are made of pn
It has a p-type bipolar transistor structure. That is, the p-type GaAs layer 10 is a p-type emitter layer and an n-type GaAs
The s layer 11 is an n-type base layer, and the p-type magnetic semiconductor layer 2 is a p-type collector layer. The p-type GaAs layer 12 becomes a p-type emitter contact layer. Also, ohmic electrodes 13, 14,
Reference numeral 15 denotes an emitter electrode, a base electrode, and a collector electrode.

When the bipolar transistor is in a normal forward operation state, a reverse bias state exists between the collector and the base. Therefore, when the base-emitter voltage is lower than the so-called on-voltage, the collector current does not flow, and the p-type magnetic semiconductor layer (p-type collector layer) 2 is depleted and enters a paramagnetic state.

However, when the base-emitter voltage is higher than the on-state voltage, a large collector current flows, and a large amount of holes flow into the p-type magnetic semiconductor layer (p-type collector layer) 2. Magnetic semiconductor layer (p-type collector layer)
2 is in a ferromagnetic state.

Therefore, a voltage is applied to the electrodes 13, 14, 15 to bring the collector-base into a reverse bias state as described above and change the voltage between the base and the emitter, that is, the p-type magnetic semiconductor layer 2 By changing the carrier density inside, the magnetic state of the p-type magnetic semiconductor layer 2 can be controlled.

When such a p-type magnetic semiconductor layer 2 is brought closer to a magnetic recording medium such as a magnetic tape or a magnetic disk, the magnetic state of the magnetic recording medium is adjusted in accordance with the magnetic state of the p-type magnetic semiconductor layer 2. Can be changed.

Here, since the p-type magnetic semiconductor layer 2 does not need to use a coil for its magnetization, the response speed of the semiconductor magnetic head is increased since there is no inductance due to the coil that hinders high-speed response.

Further, since the magnetizing signal is given in the form of a base current, it is possible to control a collector current which is a large magnetizing current with a small current, so that the sensitivity of the semiconductor magnetic head is increased.

Therefore, according to the present embodiment, it is possible to realize a semiconductor magnetic head capable of high sensitivity and high speed response. FIG. 6 shows a band diagram of each semiconductor layer in an equilibrium state for reference. CB in FIG, VB, E _F respectively the conduction band, the valence band energy, indicating the Fermi energy. In the drawing, the hatched area indicates a neutral area. (Fifth Embodiment) FIG. 7 is a sectional view showing a heterojunction bipolar transistor type semiconductor magnetic head according to a fifth embodiment of the present invention. Parts corresponding to those of the semiconductor magnetic head of FIG. 4 are denoted by the same reference numerals as in FIG.
Detailed description is omitted.

This embodiment is different from the fourth embodiment in that
In this example, the semiconductor material of the p-type GaAs layer (p-type emitter layer) 10 has a larger band gap energy than the semiconductor material of the n-type GaAs layer (n-type base layer) 11. That is, the present embodiment is an example in which the carrier density of the p-type magnetic semiconductor layer is controlled by the heterojunction bipolar transistor.

This will be described according to the manufacturing process. First, a p-type GaAs layer 10 (film thickness:
500 nm, p-type carrier concentration: about 5 × 19 cm ⁻³ ),
p-type Al _x Ga _{1 -x} As grading layer 16 (Al composition x = 0 → 0.3, film thickness: 30 nm, p-type carrier concentration: about 1 × 18 cm −3), p-type Al _0.3 Ga _0.7 As layer 17 (Thickness: 100 nm, p-type carrier concentration: about 1 × 1
8 cm ⁻³ ), p-type Al _x Ga _{1 -x} As grading layer 18 (Al composition x = 0.3 → 0. Film thickness: 30 nm, p-type carrier concentration: about 1 × 18 cm ⁻³ ), n-type GaAs layer 1
1 (film thickness: 100 nm, n-type carrier concentration: about 8 × 18
cm ^-3 ), p-type magnetic semiconductor layer (In _0.95 Mn _0.05 As)
Layer) 2 (film thickness: 100 nm, p-type carrier concentration: about 5 ×)
17 cm ⁻³ ), p-type GaAs layer 12 (film thickness: 100 n)
m, p-type carrier concentration: about 5 × 19 cm ⁻³ ) are sequentially formed by MBE.

In this embodiment, the p-type GaAs layer 10 is an emitter contact layer, and the p-type Al _0.3 Ga _0.7 As layer 17
Is a p-type emitter layer, n-type GaAs layer 11 is an n-type base layer, p-type magnetic semiconductor layer 2 is a p-type collector layer, and p-type GaAs
The s layer 12 becomes a p-type collector contact layer.

The mechanism of magnetization of the p-type magnetic semiconductor layer 2 is the fourth.
This is the same as the embodiment. However, in the case of this embodiment,
Since the band gap energy of the p-type Al _0.3 Ga _0.7 As layer (p-type emitter layer) 17 is larger than that of the n-type GaAs layer (n-type base layer) 11, the n-type GaAs layer (n-type base layer) 11 From p-type Al _0.3 Ga _0.7 As
The impurity concentration of the n-type GaAs layer (n-type base layer) 11 can be increased while the back injection of electrons into the layer (p-type emitter layer) 17 is kept low.

Therefore, according to the present embodiment, it is possible to make use of a heterojunction bipolar transistor having a low base resistance and a high current amplification factor, thereby enabling a higher-speed operation than the semiconductor magnetic head of the fourth embodiment. And a semiconductor magnetic head with high sensitivity can be realized.

FIG. 8 shows a band diagram of each semiconductor layer in an equilibrium state for reference. CB in FIG, VB, E _F respectively the conduction band, the valence band energy, indicating the Fermi energy. In the drawing, the hatched area indicates a neutral area. (Sixth Embodiment) FIG. 9 is a schematic diagram showing a main part of a magnetic recording and reproducing system according to a sixth embodiment of the present invention.

This magnetic recording / reproducing system is roughly divided into a magnetic head section 21 according to the present invention and a magnetic tape 22.
And a magnetic recording medium comprising: It should be noted that a cassette for accommodating the magnetic tape 22, a drive mechanism for running the magnetic tape, and the like are omitted.

The magnetic head unit 21 includes a semiconductor substrate (for example, a Si substrate or a GaAs substrate) and a semiconductor substrate 23.
A plurality of semiconductor magnetic heads 24 ₁ , 2 integrated on
4 ₂ , 24 ₃ ...

Here, the semiconductor magnetic heads 24 ₁ , 24
For example, any of the ones described in the first to fifth embodiments is used as ₂ , 24 ₃ . Also, the semiconductor magnetic heads 24 ₁ , 24 ₂ , 24 ₃ ... Are alternately arranged to reduce crosstalk.

The magnetic tape 22 includes a semiconductor magnetic head 24
Tracks 25 ₁ , 25 of the same number as ₁ , 24 ₂ , 24 ₃ .
It is divided into _2, 25 _3. According to the present embodiment, the use of the semiconductor magnetic heads 24 ₁ , 24 ₂ , 24 ₃ ... Eliminates the necessity of the coil portion of the magnetic head portion which conventionally occupies a large area. Can be reduced to, for example, a small area of 0.15 to 1 μm ² or less. Thus, a highly integrated semiconductor magnetic head unit 21 can be realized.

Therefore, according to the present embodiment, it is possible to realize a magnetic recording / reproducing system smaller in size than the conventional one. If the same size as the conventional one is sufficient, a magnetic recording / reproducing system with a higher density track can be realized.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the case where the present invention is applied to a magnetic head has been described. However, the present invention can also be applied to devices such as a motor, an actuator, and an optical deflector using magnetism. That is, the present invention is applicable to all devices using conventional magnets.

In the above embodiment, an In _0.95 Mn _0.05 As layer containing InAs, which is a III-V compound semiconductor, as a base and Mn as a magnetic impurity was used as the magnetic semiconductor layer. At least one of
A group III-V compound semiconductor other than InAs composed of a group III element and at least one group V element of As, P and Sb other than InAs may be used as a base. It is also possible to use magnetic impurities other than Mn.

In the fourth and fifth embodiments, the emitter layer, the base layer, and the collector layer are formed on the substrate in this order, but the collector layer, the base layer, and the emitter layer are formed in this order. Is also good. In addition, various modifications can be made without departing from the scope of the present invention.

[0072]

As described above, according to the present invention, by using a magnetic semiconductor layer whose magnetic order changes according to the internal carrier density as a magnetization layer, it is possible to control the carrier density in the magnetic semiconductor layer. A new magnetic semiconductor device based on the principle can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a Schottky type semiconductor magnetic head according to a first embodiment of the present invention;

FIG. 2 is a sectional view showing a Schottky type semiconductor magnetic head according to a second embodiment of the present invention;

FIG. 3 is a sectional view showing a pn diode type semiconductor magnetic head according to a third embodiment of the present invention;

FIG. 4 is a band diagram of each semiconductor layer constituting the semiconductor magnetic head of FIG. 3 in an equilibrium state;

FIG. 5 is a sectional view showing a bipolar transistor type semiconductor magnetic head according to a fourth embodiment of the present invention;

FIG. 6 is a band diagram of each semiconductor layer constituting the semiconductor magnetic head of FIG. 5 in an equilibrium state;

FIG. 7 is a sectional view showing a heterojunction bipolar transistor type semiconductor magnetic head according to a fifth embodiment of the present invention;

FIG. 8 is a band diagram of each semiconductor layer constituting the semiconductor magnetic head of FIG. 7 in an equilibrium state;

FIG. 9 is a schematic diagram showing a main part of a magnetic recording and reproducing system according to a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... p-type GaAs substrate 2 ... p-type magnetic semiconductor layer (first semiconductor layer) 3 ... Schottky electrode (control electrode) 4 ... p-type ohmic electrode (control electrode) 5 ... InGaP intermediate layer 6 ... n-type GaAs layer (Third semiconductor layer) 7 n-type GaAs layer 8 p-type GaAs layer (second semiconductor layer) 9 n-type ohmic electrode (control electrode) 10 p-type GaAs layer (fourth semiconductor layer) 11 ... n-type GaAs layer (fifth semiconductor layer) 12 ... p-type GaAs layer (sixth semiconductor layer) 13 ... p-type ohmic electrode (control electrode) 14 ... n-type ohmic electrode (control electrode) 15 ... p-type ohmic electrode (control electrode) 16 ... p-type AlGaAs grading layer 17 ... p-type Al _0.3 Ga _0.7 As layer (fourth semiconductor layer) 18 ... p-type AlGaAs grading layer 21 ... magnetic head unit 22 ... magnetic tape 23 The semiconductor substrate 24 _1, 24 _2, 24 ₃ ... semiconductor magnetic head 25 _1, 25 _2, 25 ₃ ... Track

Claims (6)

[Claims] A first conductivity type first semiconductor layer provided on a semiconductor substrate and having a magnetic order that changes according to an internal carrier density; and a carrier density in the first semiconductor layer, the And a control electrode for controlling the magnetic order of the semiconductor layer. 2. The magnetic semiconductor device according to claim 1, wherein said control electrode is in Schottky contact with said first semiconductor layer. 3. The method according to claim 1, further comprising the step of:
A second semiconductor layer of a first conductivity type having an impurity concentration higher than that of the first semiconductor layer is provided. A second semiconductor layer having an impurity concentration lower than that of the second semiconductor layer is provided below or above the first semiconductor layer. A third semiconductor layer of two conductivity type is provided; first and second electrodes in ohmic contact with the second and third semiconductor layers are provided; and the first and second electrodes are connected to the control electrode. The magnetic semiconductor device according to claim 1, wherein: 4. A semiconductor device comprising: a fourth semiconductor layer of a first conductivity type, a fifth semiconductor layer of a second conductivity type, a first semiconductor layer, and an impurity concentration lower than that of the first semiconductor layer. And a third, fourth and fifth electrode in ohmic contact with the fourth, fifth and sixth semiconductor layers, respectively. 2. The magnetic semiconductor device according to claim 1, wherein the third, fourth, and fifth electrodes are used as the control electrodes. 5. The base of the first semiconductor layer is Ga, In.
And at least one group III element of Al and Al;
I comprising at least one group V element of P and Sb
5. The magnetic semiconductor device according to claim 1, wherein the magnetic semiconductor device is a II-V compound semiconductor, and the base contains Mn as a magnetic impurity. 6. A magnetic head comprising the magnetic semiconductor device according to claim 1; and a magnetic recording medium for holding magnetization induced by the magnetic head. Magnetic recording / reproducing device.