JPH11340575A - Superlattice semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost superlattice semiconductor light-emitting device, capable of being simply manufactured and stably and continuously operating at room temperature. SOLUTION: This device is a heterojunction pin type diode semiconductor device, having an intrinsic semiconductor i-layer 15 with a superlattice structure. The intrinsic semiconductor i-layer 15 is formed by laminating a plurality of cyclic layers formed by a barrier layer 21, a quantum well layer 22, the barrier layer 21, and an activated layer 23 in this order. Each thickness of the quantum well layer 22 and the activated layer 23 is set to that a quantization level Γ1 of the quantum well lyaer 22 is made practically equal to a quantization level L1 and Γ1 of the activated layer 23 adjacent to the quantum well layer 22. Light is emitted after the electrons existing in the quantization level Γ1 of the quantum well layer 22 is made to underge transition to a quantization level L1 and Γ1 of the activated layer 23 adjacent to the quantum well layer 22, and a quantization level Γ2 of the activated layer 23 to its quantization level Γ1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a superlattice semiconductor light emitting device having a superlattice structure.

[0002]

2. Description of the Related Art In recent years, light-emitting elements that can be used in light sources for optical communication and measurement, optical integrated circuits, and the like have been actively studied. Recently, for example, in the prior art document "Notomi et al.," Quantum well layer intersubband transition laser ", Applied Physics, Vol. 64, No. 7, pp. 672-677, 199.
As described in "5 Years", a semiconductor laser having a structure different from a semiconductor laser widely used at present is proposed. The semiconductor laser disclosed in the above-mentioned prior art document is called a quantum cascade laser, and realizes laser oscillation using transition between subbands of a quantum well of a superlattice semiconductor.

In a quantum well layer of a superlattice semiconductor having such a superlattice structure, electrons of a second quantization level (second levelΓ2 points) are converted to a first quantization level (first level). Level Γ1
In order to emit light by relaxing to (point), it is necessary to realize a so-called population inversion in which the number of electrons at the second quantization level is larger than the number of electrons at the first quantization level. . In this conventional quantum cascade laser, electrons at the second quantization level of the quantum well layer are transited to the first quantization level of a quantum well layer spatially separated from the quantum well layer. As described above, by using a special structure in which the period of the superlattice is not constant, the population inversion is realized, and the electrons at the second quantization level of the quantum well layer are separated from the quantum well layer spatially separated from the quantum well layer. Light is emitted by transitioning to the first quantization level of the well layer.

[0004]

However, in the above-described quantum cascade laser using the intersubband transition of the conventional example, in order to obtain an effective population inversion between subbands, a special superlattice period is not constant. It is necessary to produce a superlattice with a periodic structure, and it is difficult to design and grow the device.
There was a problem that the price became high. Further, since electrons of the second quantization level of the quantum well layer are shifted to the first quantization level of the quantum well layer which is spatially separated from the quantum well layer and emit light, the second quantum level is emitted. There has been a problem that the transition probability between the quantization level and the first quantization level is low, and the luminous efficiency is low. In addition, since electrons that do not contribute to light emission raise the temperature of the device, there is a problem that the device may be destroyed and reliability is poor.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to produce a superlattice semiconductor light emitting device which can be manufactured more easily and at a lower cost than conventional examples, and which can operate stably and continuously at room temperature. Is to provide.

[0006]

According to a first aspect of the present invention, there is provided a superlattice semiconductor light emitting device comprising an intrinsic semiconductor layer having a superlattice structure between two electrodes, to which a reverse bias voltage is applied. In the superlattice semiconductor element, the intrinsic semiconductor layer is formed by laminating a plurality of layers for one cycle in which a first barrier layer, a quantum well layer, a second barrier layer, and an active layer are sequentially formed. And the quantum well layer and the quantum well layer so that the quantization level Γ1 of the quantum well layer and the quantization levels L1 and Γ1 of the active layer adjacent thereto have substantially the same energy level. Each thickness or each composition ratio of the active layer is set, and the quantization level Γ1 of the quantum well layer is set.
Is changed to the quantization level L1 and Γ1 of the active layer adjacent thereto, and then the luminescence is obtained by making a transition from the quantization level Γ2 of the active layer to the quantization level Γ1. It is characterized by the following.

A superlattice semiconductor light emitting device according to a second aspect is the superlattice semiconductor light emitting device according to the first aspect.
The intrinsic semiconductor layer is an intrinsic semiconductor i layer, and the superlattice semiconductor light emitting device further includes a p-type semiconductor layer and an n-type semiconductor layer sandwiching the intrinsic semiconductor i layer between the two electrodes. The superlattice semiconductor light emitting device is a pin diode device.

Further, the superlattice semiconductor light emitting device according to claim 3 is the superlattice semiconductor light emitting device according to claim 1, wherein the intrinsic semiconductor layer is an intrinsic semiconductor i layer, and the superlattice semiconductor light emitting device is A first n-type semiconductor layer and a second n-type semiconductor layer sandwiching the intrinsic semiconductor i-layer between the two electrodes; and the superlattice semiconductor light-emitting element is a nin-type semiconductor element. It is characterized by.

According to a fourth aspect of the present invention, there is provided a superlattice semiconductor light emitting device according to any one of the first to third aspects, wherein a predetermined impurity is added to the quantum well layer by 1 × 10 4. ^The n-type semiconductor layer is characterized by being doped by ^{16 to} 1 × 10 ¹⁸ / cm ³ .

A superlattice semiconductor light emitting device according to a fifth aspect is the superlattice semiconductor light emitting device according to the first aspect.
The intrinsic semiconductor layer is an intrinsic semiconductor i-layer, and the superlattice semiconductor light-emitting element has the intrinsic semiconductor i-layer interposed between the two electrodes and has a predetermined impurity of 1 × 10 ^{16 to} 5 × 10 ^16. The semiconductor device further includes a first n ⁺ -type semiconductor layer and a second n ⁺ -type semiconductor layer doped at a predetermined high concentration of × 10 ¹⁸ / cm ³ , and the superlattice semiconductor light-emitting device is an n ⁺ in ⁺ -type semiconductor layer. It is characterized by being an element.

Further, the superlattice semiconductor light emitting device according to claim 6 is the superlattice semiconductor light emitting device according to claim 2, wherein when light is incident on the intrinsic semiconductor i layer via the p-type semiconductor layer, The electrons in the valence band of the quantum well layer to which the light is incident are caused to transition to the quantization level Γ1 of the quantum well layer other than the quantum well layer, and thereafter, the quantization levels L1 and L1 of the active layer adjacent thereto are set. After the transition to # 1, the light emission is obtained by transitioning from the quantization level # 2 of the active layer to the quantization level # 1.

A superlattice semiconductor light emitting device according to a seventh aspect is the superlattice semiconductor light emitting device according to any one of the first to sixth aspects, wherein the intrinsic semiconductor layer is interposed between the superlattice semiconductor light emitting device and the intrinsic semiconductor layer. It is characterized in that laser oscillation is provided by providing two reflecting surfaces provided to face each other so as to reflect at least a part of the light emitted in step (1).

Further, the superlattice semiconductor light emitting device according to claim 8 is the superlattice semiconductor light emitting device according to any one of claims 1 to 6, wherein the intrinsic semiconductor layer is formed by using a crystal growth method. The superlattice semiconductor light-emitting element has two reflecting surfaces provided so as to sandwich the intrinsic semiconductor layer and to reflect at least a part of light emitted from the intrinsic semiconductor layer. And the two reflecting surfaces sandwich the intrinsic semiconductor layer between two layers of an AlGaAs layer or an AlAs layer when the intrinsic semiconductor layer is formed using a crystal growth method. After forming the intrinsic semiconductor layer as described above, the superlattice semiconductor light emitting device is oxidized to form a highly reflective film made of Al ₂ O ₃ .

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment> FIG. 1 is a sectional view showing a superlattice semiconductor light emitting device 10 according to an embodiment of the present invention. As shown in FIG. 1, the superlattice semiconductor light emitting device of the present embodiment is a heterojunction pin type diode semiconductor device including an intrinsic semiconductor i layer 15 having a superlattice structure. The barrier layer 21, the quantum well layer 22, the barrier layer 21 (hereinafter, the two barrier layers are referred to as the barrier layer 21), and the active layer 23 are sequentially formed, and a layer for one cycle is laminated in plural cycles. Be formed. Also, the quantum well layer 22 and the active layer 23 are set such that the quantization level Γ1 of the quantum well layer 22 and the quantization levels L1 and Γ1 of the active layer 23 adjacent thereto have substantially the same energy level. After the electron existing at the quantization level Γ1 of the quantum well layer 22 is transited to the quantization levels L1 and Γ1 of the active layer 23 adjacent thereto, the thickness of the active layer 23 is changed. It is characterized in that light emission is obtained by making a transition from the quantized level # 2 to the quantized level # 1.

FIGS. 3 to 8 are cross-sectional views showing the steps of manufacturing the superlattice semiconductor light emitting device 10 of FIG. 1. For the steps of manufacturing the superlattice semiconductor light emitting device 10 of this embodiment, see FIGS. This will be described below.

(1) As shown in FIG. 3, n made of Si
A 300 μm-thick n-type semiconductor substrate made of n-type GaAs doped with a doping amount of, for example, 10 ¹⁸ / cm ³ and having upper and lower plane orientations (1,1,1) is placed in an acetone solution. Ultrasonic cleaning was performed to remove the organic impurity layer 20a attached to the surface. (2) After the above-mentioned cleaning, as shown in FIG. 4, after the surface is completely dried, the surface of the semiconductor substrate 20 is cleaned with an ammonia-based etching solution (ammonia: hydrogen peroxide solution: water = 2 ° C.) at 25 ° C. 1:96 (mass ratio) for 5 minutes, the surface layer of 0.5 to 0.5 μm is removed, and the stress generated during the substrate surface treatment (mirror treatment) is reduced.
A layer having dislocations can be removed, and good crystal growth can be achieved.

(3) After performing a heat treatment at 650 ° C. in a vacuum to completely remove the surface oxide layer, as shown in FIGS. 1 and 5, the following layers were formed by successively growing crystals. (A) n-type Al _0.4 Ga doped with n-type impurity ions of Si, for example, at a doping amount of 5 × 10 ¹⁷ / cm ³
_A 1 μm thick n-type buffer layer 17 of _0.6 As. (B) An i-type cladding layer 16 made of i-type Al _0.4 Ga _0.6 As and having a thickness of 500 °. (C) 1 μm thick intrinsic semiconductor i-layer 15 having a superlattice structure. Here, the intrinsic semiconductor i-layer 15 is formed of the first barrier layer 2
1, a quantum well layer 22, a second barrier layer 21, and an active layer 23 are formed in this order.
The intrinsic semiconductor i-layer 15 is formed by alternately repeating the barrier layer 21 and the quantum well layer 22 or the active layer 23 in a plurality of periods such as 00 periods. The barrier layer 21 has a superlattice structure, and the barrier layer 21 is made of AlAs having a thickness of 45 °.
The active layer 2 is made of GaAs having a thickness of 40 °.
3 is made of GaAs having a thickness of 55 °. The intrinsic semiconductor i-layer 15 is formed in 15 to 100 periods in a preferred embodiment, and is formed in 50 periods in a more preferred embodiment. (D) An i-type cladding layer 14 of i-type GaAs having a thickness of 500 °. (E) A p-type impurity ion of Be (beryllium) doped with a doping amount of 1 × 10 ¹⁸ / cm ^3, for example.
A 2000-mm-thick p-type cap layer 13 of type Al _0.4 Ga _0.6 As.

(4) As shown in FIG. 6, Mn / Au (1000/150) is formed on the upper surface of the uppermost p-type cap layer 13.
0 °) was formed. Here, the electrode 11
Forms an electrode material 11a by a lift-off method using a photosensitive organic thin film (resist pattern) 18;
A light output hole 11b penetrating in the thickness direction is formed at the center thereof to form the electrode 11 in a ring shape.
Next, as shown in FIG.
a was covered with a resist, and mesa etching was performed to cut off the connection between the electrodes of a plurality of devices, thereby performing device isolation. (5) Further, as shown in FIG.
AuGe / Ni / Au (= 1000Å / 300)
({1500}). (6) Finally, with respect to the element on which the electrode 12 is formed, 4
Heat treatment was performed at 00 ° C. for 1.5 minutes.
In step 2, an ohmic connection was obtained. Through the above manufacturing steps, the superlattice semiconductor light emitting device 10 is obtained.

As shown in FIG. 1, the positive electrode of the variable voltage DC power supply 30 is connected to the electrode 12 while the DC power supply 3
By connecting the negative electrode of 0 to the electrode 11, a reverse bias voltage is applied to the superlattice semiconductor light emitting device 10.

In the superlattice semiconductor light emitting device 10 configured as described above, a reverse bias voltage is applied to the electrodes 11 and 12.
When the voltage is applied in between, the quantization level of the quantum well layer 22 Γ1
And the quantization levels L1 and Γ of the active layer 23 adjacent thereto.
So that 1 and 1 have substantially the same energy level,
The respective thicknesses of the quantum well layer 22 and the active layer 23 are set, and electrons existing at the quantization level Γ1 of the quantum well layer 22 are transited to the quantization levels L1 and 活性 1 of the active layer 23 adjacent thereto. Thereafter, light emission is obtained by making a transition from the quantization level # 2 of the active layer 23 to the quantization level # 1. Further, since the intrinsic semiconductor i-layer 15 is stacked in a plurality of cycles, light emission occurs over a period, and light emission having a large light emission intensity can be obtained. Here, the emitted light changes from the quantization level # 2 of the active layer 23 to the quantization level # 1.
Is light having a wavelength corresponding to the energy of the difference at the time of transition to.

Here, the quantization level L1 and the quantization level Γ1
Is a level point determined in advance from the energy structure diagram of, for example, GaAs, which represents energy with respect to the wavelength vector with respect to the upper end of the valence band, as is well known.

That is, the reverse bias voltage is applied between the electrodes 11,
12, the electrons that flowed into the intrinsic semiconductor i-layer 15 as the superlattice semiconductor layer are usually at the first quantization level Γ1, which is the lowest level of the quantum well layer 22, but were applied. When transitioning to the adjacent active layer 23 according to the reverse bias voltage, when the energy of the first quantization level Γ1 and the energy of the first quantization level L1 of the transition destination active layer 23 are substantially equal to each other. , These two subbands resonate with each other, and the electrons easily transition to the first quantization level L1. The first quantized level L1 at the transition destination resonates with the second quantized level Γ2 of the quantum well layer, and electrons are transferred to the first quantized level L1 and the second quantized level L2. You can go back and forth in position # 2 freely. Here, the quantization level Γ1 of the quantum well layer 22 and the quantization level L of the active layer 23 adjacent thereto.
1 and the quantization levels L1 and Γ of the active layer 23.
As a method for easily obtaining an electric field that resonates 2, in the present embodiment, these three quantization levels are resonated by changing the thicknesses of the quantum well layer 22 and the active layer 23. In the latter case, since the effective mass of electrons is different between the point L and the point 上昇, a difference occurs in the increase in the subband level due to the quantum size effect when the thickness of the active layer 23 is reduced.
It is possible to resonate the L1 point and the Γ2 point of the same active layer 23.

The present invention is not limited to the method for resonating the above three quantization levels, but the present invention is not limited to this. The material composition of the quantum well layer 22 and the active layer 23 is determined by the three quantization levels. You may change it so that it may become substantially the same level. In this case, the composition of the quantum well layer 22 is GaAs, and the composition of the active layer 23 serving as the light emitting layer is Al _x Ga _{1 -x} As (0 <x <
0.4). Here, the quantum well layer 22 and the active layer 23
Have the same 60 ° thickness.

When electrons move in the intrinsic semiconductor i-layer 15 having the superlattice structure configured as described above, a large amount of electrons may be accumulated because the effective mass of the electrons at the point L is large and the state density is large. Can be. Usually, electrons undergo phonon scattering, and immediately transition from the L1 point to the first quantized level Γ1 point, which is a low level. However, during laser oscillation, the transition to the low level due to phonon scattering is suppressed. L
The transition from the Γ2 point that resonates with one point to the Γ1 point results in a direct transition by light emission.

In the above embodiment, light is emitted using electrons generated by application of a reverse bias voltage. However, the present invention is not limited to this, and light having a predetermined intensity is incident through the light output hole 11b. The electrons in the valence band of the quantum well layer 22 to which light is incident are transferred to the quantum well layers 22 other than the quantum well layer 22.
After transition to the quantization level Γ1 of the active layer and then to the quantization level L1 and Γ1 of the active layer adjacent thereto,
Light emission may be obtained by making a transition from the quantization level # 2 of the active layer to the quantization level # 1. That is, a predetermined reverse bias voltage is applied between the electrodes 11 and 12, and the intrinsic semiconductor is formed from the hole 11b of the electrode 11 through the p-type cap layer 13 and the i-type clad layer 14 as shown in FIG. When light is incident on the quantum well layer 22 of the i-layer 15, the intrinsic semiconductor i-layer 15 having a superlattice structure operates as follows. That is, electrons in the valence band of the quantum well layer 22 are excited by the incident light and transit to the first quantization level Γ1 point of the quantum well layer 22. As a result, carriers that are electrons are generated at the first quantization level Γ1 point of the quantum well layer 22. First of the quantum well layer 22
The electrons excited at the quantization level Γ1 point of the active layer 23 have the quantization levels L1 and Γ of the active layer 23 adjacent thereto, as described above.
After the transition to 1, the light emission is obtained by transitioning from the quantization level # 2 of the active layer 23 to the quantization level # 1.

In the present embodiment, the light emitted from the intrinsic semiconductor i-layer 15 is, as shown in FIG. 1, from the side parallel to the thickness direction of the intrinsic semiconductor i-layer 15 in the thickness direction. It is configured to output in a direction perpendicular to the direction. However, the present invention is not limited to this, and the light emitted from the intrinsic semiconductor i-layer 15 is transmitted through the light output hole 11h provided in the electrode 11 through the i-type cladding layer 14 and the p-type cap layer 13. The signal may be output, or the signal may be output from the n-type semiconductor substrate 20 via the i-type cladding layer 16, the n-type buffer layer 17, and the n-type semiconductor substrate 20. In the case of outputting from the n-type semiconductor substrate 20 side, the i-type cladding layer 1
6, the n-type buffer layer 27 and the n-type semiconductor substrate 20 are formed thinly so as to transmit light, and the electrode 12
A light output hole (not shown) is formed in the same manner as the electrode 11, and the generated light is output from the hole.

<Modification> Next, a modification of the laser diode using the superlattice semiconductor light emitting device 10 will be described below. In the modification, first and second mirror layers (not shown) are formed on two sides of the intrinsic semiconductor i-layer 15 parallel to the thickness direction, respectively, as compared with the above embodiment. It is characterized by. Here, the first
The second mirror surface layer and the second mirror surface layer are formed to face each other with the intrinsic semiconductor i-layer 15 interposed therebetween, and each constitute a known Fabry-Perot mirror surface.

Here, the Fabry-Perot mirror surface is, for example, three times with respect to light generated in the intrinsic semiconductor i-layer 15.
In this modification, the orientation of the crystal of the n-type semiconductor substrate 20 is set to a predetermined direction, and the two side surfaces of the intrinsic semiconductor i-layer 15 are each a predetermined surface. After forming the intrinsic semiconductor i-layer 15 so as to have a cleavage surface, the side surface itself was used as a Fabry-Perot mirror surface by cleavage. In this case, Fabry
The reflectivity of the two side surfaces of the intrinsic semiconductor i-layer 15 used as the low mirror surface is not limited to 30%, and may be configured to reflect at least a part of light generated in the intrinsic semiconductor i-layer 15. In the modification, the interval between the two side surfaces of the intrinsic semiconductor i-layer 15 was set to 300 μm. However, the present invention is not limited to this, and the intrinsic semiconductor i
The distance between the two sides of the layer may be 100 μm or 50 μm.
It may be 0 μm, ie the spacing can be set arbitrarily so as to form a Fabry-Perot resonator.

With the above configuration, a Fabry-Perot resonator having two side surfaces can be formed on the intrinsic semiconductor i-layer 15 in the superlattice semiconductor light-emitting device 10. Is repetitively reflected by the Fabry-Perot resonator inside it and resonates, causing the superlattice semiconductor light emitting device 10 to oscillate in the laser mode, that is, to oscillate the laser at a large intensity.

<Another Modified Example> When a normal surface emitting laser is formed, a reflection film is formed by a multilayer film structure. However, a quantum intersubband transition laser has an emission wavelength as long as several μm. For this reason, in the case of a multilayer reflective film, the film thickness is as large as several tens of μm, and it is extremely difficult to form it during crystal growth. In place of the above-described reflection surface in the above-described modification, the intrinsic semiconductor i-layer 15 having a superlattice structure is formed by a crystal growth method, and at the same time, the intrinsic semiconductor i-layer 1 is formed.
5 and the cladding layer 16, and between the intrinsic semiconductor i-layer 15 and the cladding layer 14, an AlGaAs layer or AlAs
By forming an Al ₂ O ₃ (alumina) film by performing a heat treatment in an oxidizing atmosphere to form an Al ₂ O ₃ (alumina) film, the upper and lower surfaces of the intrinsic semiconductor i-layer 15 have high reflectance made of alumina. A film may be formed.
At this time, there is an advantage that the reflection film can be easily formed as compared with the conventional example.

<Further Modifications> In the above embodiments and modifications, the layers at the upper and lower ends of the intrinsic semiconductor i-layer 15 may be quantum well layers 22 and 23 or barrier layers 21. Good.

In the above embodiments and modifications, the superlattice semiconductor light emitting device 10 is a pin diode device. However, the present invention is not limited to this, and the p-type cap layer 13 may be replaced with an n-type cap layer. 13 may be provided as a nin-type semiconductor device. At this time, for example, the material of the n-type cap layer 13 is GaAs doped with silicon at a concentration of 1 × 10 ¹⁸ / cm ³ , and the i-type clad layer 14
Is AlGaAs, and the material of the intrinsic semiconductor i-layer 15, the material of the i-type cladding layer 16, and the material of the n-type buffer layer 17 are the same as described above.

In the above-mentioned nin type semiconductor device,
Instead of the n-type cap layer 13 and the n-type buffer layer 17, a predetermined high impurity concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁸ / cm ³ is added to the n-type cap layer 13 and the n-type buffer layer 17. By providing a first n ⁺ -type semiconductor layer and a second n ⁺ -type semiconductor layer doped with, an n ⁺ in ⁺ -type semiconductor element may be formed.

<Effects of Embodiment and Modification> As described above in detail, according to the superlattice semiconductor light emitting device of the embodiment and the modification, the two types of quantum well layers 22 having different effective masses of electrons and the active layers are provided. An intrinsic semiconductor i-layer 15 in which a layer 23 and a barrier layer 21 are stacked, and when a predetermined reverse bias voltage is applied, the active layer 23 has a second quantization level between the first and second quantization levels # 2 and # 1. Light having a wavelength corresponding to the energy of the difference can be generated and output. Further, in the superlattice semiconductor light emitting device of the embodiment, since the superlattice period is configured using the intrinsic semiconductor i-layer 15 having a simple periodic structure, the conventional quantum cascade using the intersubband transition is used. It can be manufactured at lower cost than a laser. Furthermore, since a stable population inversion is obtained even at room temperature, a laser structure element having a reflection surface can also oscillate at room temperature.

[0036]

As described above in detail, according to the superlattice semiconductor light-emitting device of the present invention, an ultra-semiconductor having a superlattice structure between two electrodes and having a reverse bias voltage applied thereto In the lattice semiconductor element, the intrinsic semiconductor layer is formed by laminating a plurality of layers for one cycle in which a first barrier layer, a quantum well layer, a second barrier layer, and an active layer are sequentially formed. And the quantization level Γ1 of the quantum well layer and the quantization level L1 of the active layer adjacent thereto.
And the thickness and the composition ratio of the quantum well layer and the active layer are set such that the energy levels of the quantum well layer and the active layer become substantially the same. Is changed to the quantization levels L1 and Γ1 of the active layer adjacent thereto, and then the light is obtained by making a transition from the quantization level の 2 of the active layer to the quantization level Γ1. Therefore, the semiconductor device includes two types of quantum well layers having different effective masses of electrons and an intrinsic semiconductor layer in which an active layer and a barrier layer are stacked, and when a predetermined reverse bias voltage is applied, the second and the active layers of the active layer are different. Light having a wavelength corresponding to the energy of the difference between the first quantization levels # 2 and # 1 can be generated and output. In the superlattice semiconductor light emitting device of the embodiment, since the superlattice period is formed using an intrinsic semiconductor layer having a simple periodic structure, the conventional quantum cascade laser using intersubband transition is used. In comparison, it can be manufactured at low cost. Furthermore, since a stable population inversion is obtained even at room temperature, a laser structure element having a reflection surface can also oscillate at room temperature.

In the above-described superlattice semiconductor light emitting device, the superlattice semiconductor light emitting device may be configured such that when light is incident on the intrinsic semiconductor i-layer via the p-type semiconductor layer, the quantum well layer on which light is incident. Of the valence band of the quantum well layer other than the quantum well layer, and then to the quantization levels L1 and の of the active layer adjacent thereto.
After the transition to 1, the light emission is obtained by transitioning from the quantization level # 2 of the active layer to the quantization level # 1.
Therefore, the semiconductor device includes two types of quantum well layers having different effective masses of electrons and an intrinsic semiconductor layer in which an active layer and a barrier layer are stacked, and when a predetermined reverse bias voltage is applied, the second and the active layers of the active layer are different. Light having a wavelength corresponding to the energy of the difference between the first quantization levels # 2 and # 1 can be generated and output. In the superlattice semiconductor light emitting device of the embodiment, since the superlattice period is formed using an intrinsic semiconductor layer having a simple periodic structure, the conventional quantum cascade laser using intersubband transition is used. In comparison, it can be manufactured at low cost. Furthermore, since a stable population inversion is obtained even at room temperature, a laser structure element having a reflection surface can also oscillate at room temperature.

Further, in the above-mentioned superlattice semiconductor light emitting device, the superlattice semiconductor light emitting device sandwiches the intrinsic semiconductor layer and reflects at least a part of the light emitted from the intrinsic semiconductor layer. Is provided with two reflecting surfaces provided so as to face each other, so that laser oscillation occurs.
Therefore, the semiconductor device includes two types of quantum well layers having different effective masses of electrons and an intrinsic semiconductor layer in which an active layer and a barrier layer are stacked, and when a predetermined reverse bias voltage is applied, the second and the active layers of the active layer are different. Light having a wavelength corresponding to the energy of the difference between the first quantization levels # 2 and # 1 can be generated and output. In the superlattice semiconductor light emitting device of the embodiment, since the superlattice period is formed using an intrinsic semiconductor layer having a simple periodic structure, the conventional quantum cascade laser using intersubband transition is used. In comparison, it can be manufactured at low cost. Furthermore, since a stable population inversion is obtained even at room temperature, a laser structure element having a reflection surface can also oscillate at room temperature.

Still further, in the superlattice semiconductor light emitting device, the intrinsic semiconductor layer is formed by using a crystal growth method, and the superlattice semiconductor light emitting device has the intrinsic semiconductor layer interposed therebetween, and Laser oscillation is provided by providing two reflecting surfaces provided to face each other so as to reflect at least a part of the emitted light, and the two reflecting surfaces are used for forming the intrinsic semiconductor layer by a crystal growth method. When formed by using, two layers of an AlGaAs layer or an AlAs layer are formed so as to sandwich the intrinsic semiconductor layer, and after forming the intrinsic semiconductor layer, the superlattice semiconductor light emitting element is formed. It is formed by oxidizing to form a high reflection film made of Al ₂ O ₃ . Therefore, the semiconductor device includes two types of quantum well layers having different effective masses of electrons and an intrinsic semiconductor layer in which an active layer and a barrier layer are stacked, and when a predetermined reverse bias voltage is applied, the second and the active layers of the active layer are different. Light having a wavelength corresponding to the energy of the difference between the first quantization levels # 2 and # 1 can be generated and output. In the superlattice semiconductor light emitting device of the embodiment, since the superlattice period is formed using an intrinsic semiconductor layer having a simple periodic structure, the conventional quantum cascade laser using intersubband transition is used. In comparison, it can be manufactured at low cost. Furthermore, since a stable population inversion is obtained even at room temperature, a laser structure element having a reflection surface can also oscillate at room temperature.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a superlattice semiconductor light emitting device 10 according to one embodiment of the present invention.

FIG. 2 is an energy band diagram showing a level energy with respect to a position in a thickness direction of an intrinsic semiconductor i-layer of the superlattice semiconductor light emitting device 10 of FIG.

FIG. 3 is a cross-sectional view showing a first step of the manufacturing steps of the superlattice semiconductor light emitting device 10 of FIG.

FIG. 4 is a cross-sectional view showing a second step in the manufacturing process of the superlattice semiconductor light emitting device 10 of FIG.

FIG. 5 is a cross-sectional view showing a third step in the process of manufacturing the superlattice semiconductor light emitting device 10 of FIG.

FIG. 6 is a sectional view showing a fourth step in the process of manufacturing the superlattice semiconductor light emitting device 10 of FIG.

FIG. 7 is a cross-sectional view showing a fifth step in the process of manufacturing the superlattice semiconductor light emitting device 10 of FIG.

8 is a cross-sectional view showing a sixth step in the process of manufacturing the superlattice semiconductor light emitting device 10 of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Super lattice semiconductor light emitting element, 11 and 12 ... Electrode, 11h ... Light output hole, 13 ... Cap layer, 14 ... Cladding layer, 15 ... Intrinsic semiconductor i layer, 16 ... Cladding layer, 17 ... Buffer layer, 20 ... Semiconductor Substrate, 21: barrier layer, 22: quantum well layer, 23: active layer, 30: variable voltage DC power supply.

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[Procedure amendment]

[Submission date] April 19, 1999

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[0006]

According to a first aspect of the present invention, there is provided a superlattice semiconductor light emitting device comprising an intrinsic semiconductor layer having a superlattice structure between two electrodes, and having a bias voltage applied thereto. In the lattice semiconductor element, the intrinsic semiconductor layer is formed by laminating a plurality of layers for one cycle in which a first barrier layer, a quantum well layer, a second barrier layer, and an active layer are sequentially formed. And the quantization level Γ1 of the quantum well layer and the quantization level L of the active layer adjacent thereto.
The thicknesses or the composition ratios of the quantum well layer and the active layer are set so that 1 and 実 質 2 have substantially the same energy level, and exist at the quantization level に 1 of the quantum well layer. After transitioning electrons to the quantization levels L1 and Γ2 of the active layer adjacent thereto, light is emitted by transitioning from the quantization level Γ2 of the active layer to the quantization level Γ1. And

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A superlattice semiconductor light emitting device according to a second aspect is the superlattice semiconductor light emitting device according to the first aspect.
The intrinsic semiconductor layer is an intrinsic semiconductor i layer, and the superlattice semiconductor light emitting device further includes a p-type semiconductor layer and an n-type semiconductor layer sandwiching the intrinsic semiconductor i layer between the two electrodes. The superlattice semiconductor light emitting device is a pin diode device, and the bias voltage is a reverse bias voltage.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

A superlattice semiconductor light emitting device according to a fourth aspect of the present invention further comprises a superlattice semiconductor layer having a superlattice structure between two electrodes, wherein a superlattice semiconductor is applied with a bias voltage. In the device, the superlattice semiconductor layer is formed by laminating a plurality of layers of one cycle in which a first barrier layer, a quantum well layer, a second barrier layer, and an active layer are sequentially formed. And the quantization level Γ1 of the quantum well layer and the quantization level L of the active layer adjacent thereto.
Each thickness or each composition ratio of the quantum well layer and the active layer is set so that 1 and １2 have substantially the same energy level, and a predetermined impurity is added to the quantum well layer by 1 × 10 4. Doping by ^{16 to} 1 × 10 ¹⁸ / cm ³ and n
After the electrons present at the quantization level Γ1 of the quantum well layer are transited to the quantization levels L1 and Γ2 of the active layer adjacent thereto, the quantization level Γ2 of the active layer is formed. The light emission is obtained by making a transition to the quantized level Γ1 from.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

Further, the superlattice semiconductor light emitting device according to claim 6 is the superlattice semiconductor light emitting device according to claim 2, wherein when light is incident on the intrinsic semiconductor i layer via the p-type semiconductor layer, The electrons in the valence band of the quantum well layer to which the light is incident are caused to transition to the quantization level Γ1 of the quantum well layer other than the quantum well layer, and thereafter, the quantization levels L1 and L1 of the active layer adjacent thereto are set. After the transition to # 2, light emission is obtained by transitioning from the quantization level # 2 of the active layer to the quantization level # 1.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

The superlattice semiconductor light emitting device according to claim 7 is the superlattice semiconductor light emitting device according to claim 1, wherein the intrinsic semiconductor layer is interposed between the superlattice semiconductor light emitting device and the intrinsic semiconductor layer. It is characterized in that laser oscillation is provided by providing two reflecting surfaces provided to face each other so as to reflect at least a part of the light emitted in step (1).

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

The superlattice semiconductor light emitting device according to claim 8 is the superlattice semiconductor light emitting device according to claim 1, 2, 3, 5 or 6, wherein the intrinsic semiconductor layer is formed by using a crystal growth method. The superlattice semiconductor light-emitting element has two reflecting surfaces provided so as to sandwich the intrinsic semiconductor layer and to reflect at least a part of light emitted from the intrinsic semiconductor layer. And the two reflecting surfaces sandwich the intrinsic semiconductor layer between two layers of an AlGaAs layer or an AlAs layer when the intrinsic semiconductor layer is formed using a crystal growth method. After forming the intrinsic semiconductor layer as described above, the superlattice semiconductor light emitting device is oxidized to form a highly reflective film made of Al ₂ O ₃ . A superlattice semiconductor light emitting device according to a ninth aspect is the superlattice semiconductor light emitting device according to the fourth aspect, wherein the superlattice semiconductor layer is interposed, and at least one of the light emitted from the superlattice semiconductor layer is provided. Laser oscillation is provided by providing two reflecting surfaces provided to face each other so as to reflect light of the portion. Further, the superlattice semiconductor light emitting device according to claim 10 is the superlattice semiconductor light emitting device according to claim 4, wherein the superlattice semiconductor layer is formed by using a crystal growth method, A superlattice semiconductor layer is interposed, and laser oscillation is provided by providing two reflecting surfaces provided to face each other so as to reflect at least a part of light emitted by the superlattice semiconductor layer, The two reflecting surfaces are formed when the superlattice semiconductor layer is formed using a crystal growth method.
Two layers of an AlGaAs layer or an AlAs layer are formed so as to sandwich the superlattice semiconductor layer. After forming the superlattice semiconductor layer, the superlattice semiconductor light emitting device is oxidized to form Al ₂ O. ₃ is formed by forming a high reflection film.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

<Embodiment> FIG. 1 is a sectional view showing a superlattice semiconductor light emitting device 10 according to an embodiment of the present invention. As shown in FIG. 1, the superlattice semiconductor light emitting device of the present embodiment is a heterojunction pin type diode semiconductor device including an intrinsic semiconductor i layer 15 having a superlattice structure. The barrier layer 21, the quantum well layer 22, the barrier layer 21 (hereinafter, the two barrier layers are referred to as the barrier layer 21), and the active layer 23 are sequentially formed, and a layer for one cycle is laminated in plural cycles. Be formed. Also, the quantum well layer 22 and the active layer 23 are set such that the quantization level Γ1 of the quantum well layer 22 and the quantization levels L1 and Γ2 of the active layer 23 adjacent thereto have substantially the same energy level. After the electron existing at the quantization level Γ1 of the quantum well layer 22 is shifted to the quantization levels L1 and Γ2 of the active layer 23 adjacent thereto, the thickness of the active layer 23 is changed. It is characterized in that light emission is obtained by making a transition from the quantized level # 2 to the quantized level # 1.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

In the superlattice semiconductor light emitting device 10 configured as described above, a reverse bias voltage is applied to the electrodes 11 and 12.
When the voltage is applied in between, the quantization level of the quantum well layer 22 Γ1
And the quantization levels L1 and Γ of the active layer 23 adjacent thereto.
2 so that they have substantially the same energy level,
Each thickness of the quantum well layer 22 and the active layer 23 is set, and electrons existing at the quantization level Γ1 of the quantum well layer 22 are transited to the quantization levels L1 and の 2 of the active layer 23 adjacent thereto. Thereafter, light emission is obtained by making a transition from the quantization level # 2 of the active layer 23 to the quantization level # 1. Further, since the intrinsic semiconductor i-layer 15 is stacked in a plurality of cycles, light emission occurs over a period, and light emission having a large light emission intensity can be obtained. Here, the emitted light changes from the quantization level # 2 of the active layer 23 to the quantization level # 1.
Is light having a wavelength corresponding to the energy of the difference at the time of transition to.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

In the above embodiment, light is emitted using electrons generated by application of a reverse bias voltage. However, the present invention is not limited to this, and light having a predetermined intensity is incident through the light output hole 11b. The electrons in the valence band of the quantum well layer 22 to which light is incident are transferred to the quantum well layers 22 other than the quantum well layer 22.
After transition to the quantization level Γ1 of the active layer, and then to the quantization levels L1 and Γ2 of the active layer adjacent thereto.
Light emission may be obtained by making a transition from the quantization level # 2 of the active layer to the quantization level # 1. That is, a predetermined reverse bias voltage is applied between the electrodes 11 and 12, and the intrinsic semiconductor is formed from the hole 11b of the electrode 11 through the p-type cap layer 13 and the i-type clad layer 14 as shown in FIG. When light is incident on the quantum well layer 22 of the i-layer 15, the intrinsic semiconductor i-layer 15 having a superlattice structure operates as follows. That is, electrons in the valence band of the quantum well layer 22 are excited by the incident light and transit to the first quantization level Γ1 point of the quantum well layer 22. As a result, carriers that are electrons are generated at the first quantization level Γ1 point of the quantum well layer 22. First of the quantum well layer 22
The electrons excited at the quantization level Γ1 point of the active layer 23 have the quantization levels L1 and Γ of the active layer 23 adjacent thereto, as described above.
After the transition to 2, the light emission is obtained by transition from the quantization level # 2 of the active layer 23 to the quantization level # 1.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction contents]

[0036]

As described above in detail, according to the superlattice semiconductor light emitting device of the present invention, a superlattice having an intrinsic semiconductor layer having a superlattice structure between two electrodes and being applied with a bias voltage is provided. In the semiconductor device, the intrinsic semiconductor layer is formed by laminating a plurality of layers for one cycle in which a first barrier layer, a quantum well layer, a second barrier layer, and an active layer are sequentially formed. And the quantization level Γ1 of the quantum well layer and the quantization level L1 of the active layer adjacent thereto.
And the thicknesses or composition ratios of the quantum well layer and the active layer are set so that the energy levels of the quantum well layer and the active layer become substantially the same, and the electrons existing at the quantization level Γ1 of the quantum well layer are set. Is shifted to the quantization levels L1 and Γ2 of the active layer adjacent thereto, and then the light is obtained by shifting from the quantization level Γ2 of the active layer to the quantization level Γ1. Therefore, the semiconductor device includes an intrinsic semiconductor layer in which two types of quantum well layers having different effective masses of electrons and an active layer and a barrier layer are stacked, and when a predetermined bias voltage is applied, the second and third active layers are formed. Light having a wavelength corresponding to the energy of the difference between the quantization levels # 2 and # 1 can be generated and output. In the superlattice semiconductor light emitting device of the embodiment, since the superlattice period is formed using an intrinsic semiconductor layer having a simple periodic structure, the conventional quantum cascade laser using intersubband transition is used. In comparison, it can be manufactured at low cost. Furthermore, since a stable population inversion is obtained even at room temperature, a laser structure element having a reflection surface can also oscillate at room temperature.

[Procedure amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

In the above-described superlattice semiconductor light emitting device, the superlattice semiconductor light emitting device may be configured such that when light is incident on the intrinsic semiconductor i-layer via the p-type semiconductor layer, the quantum well layer on which the light is incident. Of the valence band of the quantum well layer other than the quantum well layer, and then to the quantization levels L1 and の of the active layer adjacent thereto.
After the transition to 2, the light emission is obtained by transitioning from the quantization level # 2 of the active layer to the quantization level # 1.
Therefore, the semiconductor device includes an intrinsic semiconductor layer in which two types of quantum well layers having different effective masses of electrons and an active layer and a barrier layer are stacked, and when a predetermined bias voltage is applied, the second and third active layers are formed. Light having a wavelength corresponding to the energy of the difference between the quantization levels # 2 and # 1 can be generated and output. In the superlattice semiconductor light emitting device of the embodiment, since the superlattice period is formed using an intrinsic semiconductor layer having a simple periodic structure, the conventional quantum cascade laser using intersubband transition is used. In comparison, it can be manufactured at low cost. Furthermore, since a stable population inversion is obtained even at room temperature, a laser structure element having a reflection surface can also oscillate at room temperature.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Naoki Otani 5 Sanraya, Daiya, Seika-cho, Soraku-cho, Kyoto Prefecture AT / IR Research Institute for Environmentally Adaptable Communications (72) Inventor Norifumi Egami Kyoto Prefecture 5 Shiraya, Inaya, Seika-cho, Soraku-gun, Japan A72 R & D Co., Ltd. Environmentally Friendly Communication Research Laboratory (72) Inventor Masaaki Nakayama 3-138 Sugimoto, Sumiyoshi-ku, Osaka-shi, Osaka Prefecture Applied physics, Osaka City University In the classroom

Claims (8)

[Claims] 1. A superlattice semiconductor device comprising an intrinsic semiconductor layer having a superlattice structure between two electrodes and applied with a reverse bias voltage, wherein the intrinsic semiconductor layer comprises a first barrier layer and a quantum well. Layer and second
Of the quantum well layer, and the quantum level of the active layer adjacent to the quantum well layer Γ1. The thicknesses or composition ratios of the quantum well layer and the active layer are set such that the energy levels L1 and Ｌ1 are substantially the same, and the quantization level Γ1 of the quantum well layer is set. Is changed to the quantization level L1 and Γ1 of the active layer adjacent thereto, and then the luminescence is obtained by making a transition from the quantization level Γ2 of the active layer to the quantization level Γ1. A superlattice semiconductor light emitting device, comprising: 2. The intrinsic semiconductor layer is an intrinsic semiconductor i-layer, and the superlattice semiconductor light emitting device is provided between the two electrodes.
The superlattice semiconductor light emitting device according to claim 1, further comprising a p-type semiconductor layer and an n-type semiconductor layer sandwiching the intrinsic semiconductor i layer, wherein the superlattice semiconductor light emitting device is a pin type diode device. . 3. The intrinsic semiconductor layer is an intrinsic semiconductor i-layer, and the superlattice semiconductor light emitting device is provided between the two electrodes.
2. The semiconductor device according to claim 1, further comprising a first n-type semiconductor layer and a second n-type semiconductor layer sandwiching the intrinsic semiconductor i-layer, wherein the superlattice semiconductor light-emitting element is a nin-type semiconductor element. 3. Super-semiconductor semiconductor light emitting device. 4. A method according to claim 1, wherein a predetermined impurity is added to the quantum well layer by 1 × 1.
The superlattice semiconductor light emitting device according to claim 1, wherein the n-type semiconductor layer is doped by doping from 0 ^{16 to} 1 × 10 ¹⁸ / cm ³ . 5. The superlattice semiconductor light emitting device, wherein the intrinsic semiconductor layer is an intrinsic semiconductor i layer,
The above intrinsic semiconductor i-layer is interposed and a predetermined impurity is 1 ×
The semiconductor device further includes a first n ⁺ -type semiconductor layer and a second n ⁺ -type semiconductor layer which are doped at a predetermined high concentration of 10 ^{16 to} 5 × 10 ¹⁸ / cm ³ , and the superlattice semiconductor light-emitting element is n ⁺ 2. The super lattice semiconductor light emitting device according to claim 1, wherein the super lattice semiconductor light emitting device is an in ⁺ type semiconductor device. 6. The superlattice semiconductor light emitting device, when light enters the intrinsic semiconductor i-layer via the p-type semiconductor layer, emits electrons of the valence band of the quantum well layer to which the light enters. After the transition to the quantization level Γ1 of the quantum well layer other than the quantum well layer, and subsequently to the quantization levels L1 and Γ1 of the active layer adjacent thereto, the quantization level Γ2 of the active layer is changed. 3. The superlattice semiconductor light-emitting device according to claim 2, wherein light emission is obtained by making the transition to the quantization level Γ1 from. 7. The superlattice semiconductor light-emitting element is provided so as to sandwich the intrinsic semiconductor layer and to face at least a part of light emitted from the intrinsic semiconductor layer so as to reflect at least a part of the light emitted from the intrinsic semiconductor layer. The superlattice semiconductor light emitting device according to claim 1, wherein the superlattice semiconductor light emitting device performs laser oscillation by providing two reflecting surfaces. 8. The intrinsic semiconductor layer is formed by using a crystal growth method, and the superlattice semiconductor light emitting element sandwiches the intrinsic semiconductor layer and at least a part of light emitted from the intrinsic semiconductor layer. 2 provided to face each other so as to reflect light
Laser oscillation is provided by providing two reflecting surfaces, and the two reflecting surfaces are formed when the intrinsic semiconductor layer is formed using a crystal growth method.
Two layers are formed so as to sandwich the intrinsic semiconductor layer, and after forming the intrinsic semiconductor layer, the superlattice semiconductor light emitting device is oxidized to form a highly reflective film made of Al ₂ O _3. The superlattice semiconductor light emitting device according to claim 1, wherein the superlattice semiconductor light emitting device is formed by forming: