JP7335065B2 - light receiving and emitting device - Google Patents

Description

The present disclosure relates to a light receiving and emitting device.

2. Description of the Related Art Conventionally, as an example of a light-receiving element for receiving ultraviolet rays, an ultraviolet light-receiving element composed of a p-type gate optical FET using a GaN/AlGaN heterostructure is known (see, for example, Patent Document 1). As an example of a light-emitting element that emits ultraviolet light, an ultraviolet light-emitting element made of a Group III nitride laminate is known (see, for example, Patent Document 2).

There is also known a light emitting/receiving device that combines a light emitting element and a light receiving element to detect the state of an object to be detected between the light emitting element and the light receiving element (see, for example, Patent Document 3). Here, the state to be detected can be, for example, the concentration of a specific gas or liquid in the environment in which the light emitting/receiving device is placed, or the light emitted and reflected from the light emitting element.

WO2007/135739 WO2016/143653 JP 2016-181650 A

Here, the light-emitting element may change the characteristics of the light emitted (e.g., the light emission intensity) depending on the environment of use or changes over time. For example, in a light receiving and emitting device, if the characteristics of the light emitted by the light emitting element change, it becomes difficult to accurately determine the state of the detection target based on the detection value of the light receiving element.

An object of the present disclosure, which has been made in view of such circumstances, is to provide a light emitting/receiving device capable of detecting the state of a detection target with higher accuracy.

A light emitting/receiving device according to one embodiment includes a substrate, a light emitting element formed on the substrate and having a first nitride semiconductor laminate, and a light emitting element formed on the substrate and having a second nitride semiconductor laminate. wherein the first nitride semiconductor multilayer body is formed on the first nitride semiconductor layer containing Al and Ga, and contains Al and Ga. a second nitride semiconductor layer having a lattice constant larger than that of the first nitride semiconductor layer; and a nitride semiconductor of a first conductivity type formed on the second nitride semiconductor layer and containing Al and Ga. a light emitting layer containing Al and Ga formed on the nitride semiconductor layer of the first conductivity type; and a nitride semiconductor layer of the second conductivity type containing Al and Ga formed on the light emitting layer. and the second nitride semiconductor stacked body includes: a third nitride semiconductor layer having the same composition as the first nitride semiconductor layer; and a fourth nitride semiconductor layer having the same composition as the second nitride semiconductor layer.

According to the present disclosure, it is possible to provide a light emitting/receiving device capable of detecting the state of a detection target with higher accuracy.

1 is a cross-sectional view showing the configuration of a light emitting/receiving device according to an embodiment; FIG. FIG. 4 is a diagram for explaining reflected light and propagating light; It is a figure for demonstrating the process of the manufacturing method of a light emitting/receiving device. 4A and 4B are diagrams for explaining a step subsequent to FIG. 3 in the method of manufacturing the light receiving and emitting device; FIG. 5A and 5B are diagrams for explaining a step subsequent to FIG. 4 in the method of manufacturing the light receiving and emitting device; 6A and 6B are diagrams for explaining a step subsequent to FIG. 5 in the method of manufacturing the light receiving and emitting device; FIG. 7A and 7B are diagrams for explaining a step subsequent to FIG. 6 in the method of manufacturing the light receiving and emitting device; FIG.

Embodiments of the present disclosure will be described below with reference to the drawings. In each figure explained below, the same code|symbol may be attached|subjected to the part which has the same structure, and the overlapping description may be abbreviate|omitted.

<Structure of light receiving and emitting device>
As shown in FIG. 1 , the light emitting/receiving device 1 of this embodiment includes a substrate 2 , a light emitting element 20 and a light receiving element 30 . The light emitting device 20 is formed on the substrate 2 and has a first nitride semiconductor laminate 21 . A light receiving element 30 is formed on the substrate 2 and has a second nitride semiconductor laminate 31 .

First nitride semiconductor laminate 21 has first nitride semiconductor layer 3a containing Al and Ga. The first nitride semiconductor laminate 21 is formed on the first nitride semiconductor layer 3a, contains Al and Ga, and is a second nitride semiconductor having a lattice constant larger than that of the first nitride semiconductor layer 3a. It has a layer 4a. First nitride semiconductor laminate 21 is formed on second nitride semiconductor layer 4a and has first conductivity type nitride semiconductor layer 5 containing Al and Ga. The first nitride semiconductor laminate 21 is formed on the nitride semiconductor layer 5 of the first conductivity type and has a light emitting layer 6 containing Al and Ga. The first nitride semiconductor laminate 21 is formed on the light emitting layer 6 and has a second conductivity type nitride semiconductor layer 7 containing Al and Ga. That is, in the first nitride semiconductor multilayer body 21, on the substrate 2, the first nitride semiconductor layer 3a, the second nitride semiconductor layer 4a, the first conductivity type nitride semiconductor layer 5, the light emitting layer 6 and the A second conductivity type nitride semiconductor layer 7 is formed in this order. As shown in FIG. 1, the light emitting device 20 has an electrode 11 on the second conductivity type nitride semiconductor layer 7 . Further, the light emitting element 20 has an electrode 12 on the nitride semiconductor layer 5 of the first conductivity type. A two-dimensional electron gas layer 8a exists between the first nitride semiconductor layer 3a and the second nitride semiconductor layer 4a. The two-dimensional electron gas layer 8a is a two-dimensional electron gas (2DEG) layer in which electrons are distributed two-dimensionally, and is an electron traveling layer.

Here, for example, the word “over” in the expression “having the second nitride semiconductor layer 4a on the first nitride semiconductor layer 3a” means the second nitride semiconductor layer 4a on the first nitride semiconductor layer 3a. Although it means that two nitride semiconductor layers 4a are formed, this expression also applies when another layer further exists between the first nitride semiconductor layer 3a and the second nitride semiconductor layer 4a. included. For example, as shown in FIG. 1, even when the two-dimensional electron gas layer 8a exists between the first nitride semiconductor layer 3a and the second nitride semiconductor layer 4a, the "first nitride semiconductor layer 3a has a second nitride semiconductor layer 4a". The term "upper" has the same meaning in other relationships between layers and between layers and elements.

In addition, the word "containing" in the expression "first nitride semiconductor layer 3a containing Al and Ga" means that the layer mainly contains Al and Ga, but other elements may also be contained. included in this expression. Specifically, this expression also applies to the case where the composition of this layer is slightly changed by adding a small amount of another element (for example, an element such as As, In, P, Sb, or N is several percent or less). Of course it is included. The term "includes" also has the same meaning in expressing the compositions of other layers.

The second nitride semiconductor laminate 31 has a third nitride semiconductor layer 3b having the same composition as the first nitride semiconductor layer 3a. The second nitride semiconductor laminate 31 has a fourth nitride semiconductor layer 4b formed on the third nitride semiconductor layer 3b and having the same composition as the second nitride semiconductor layer 4a. That is, in the second nitride semiconductor laminate 31, the third nitride semiconductor layer 3b and the fourth nitride semiconductor layer 4b are formed on the substrate 2 in this order. As shown in FIG. 1, light receiving element 30 has electrodes 13 and 14 on fourth nitride semiconductor layer 4b. A two-dimensional electron gas layer 8b exists between the third nitride semiconductor layer 3b and the fourth nitride semiconductor layer 4b. The two-dimensional electron gas layer 8b is an electron transit layer, like the two-dimensional electron gas layer 8a.

Although details will be described later, the first nitride semiconductor layer 3 a and the third nitride semiconductor layer 3 b are formed by separating one nitride semiconductor lower layer 3 . Therefore, the third nitride semiconductor layer 3b has the same composition as the first nitride semiconductor layer 3a. The second nitride semiconductor layer 4a and the fourth nitride semiconductor layer 4b are formed by separating one nitride semiconductor upper layer 4 from each other. Therefore, the fourth nitride semiconductor layer 4b has the same composition as the second nitride semiconductor layer 4a. Here, similarly, the two-dimensional electron gas layer 8a and the two-dimensional electron gas layer 8b are formed by separating one two-dimensional electron gas layer 8 from each other.

<Action, effect>
As shown in FIG. 2, the light emitting/receiving device 1 is used in a state where the detection target T exists on the opposite side of the light emitting element 20 and the light receiving element 30 from the substrate 2 (upper side in the example of FIG. 2). The detection target T is, for example, water or air. Further, the light emitted by the light emitting element 20 is, for example, ultraviolet rays. The light emitting/receiving device 1 can detect the concentration of a specific substance or specific gas contained in the detection target T. FIG.
Examples of substances and expectations here include nitrites, O ₃ , NO, NO ₂ , DNA, and flames, but are not limited to these as long as they have light absorption in the ultraviolet range.
Moreover, when ultraviolet rays are used, bacteria contained in the target T can be sterilized. The light emitted from the light-emitting layer 6 of the light-emitting element 20 to the detection target T is absorbed according to the concentration of a specific substance or specific gas contained in the detection target T. Therefore, based on the intensity of the reflected light La from the detection target T received by the light receiving element 30, it is possible to detect the concentration of the specific substance or specific gas. In the case of sterilization, it is possible to confirm whether or not a sufficient amount of ultraviolet light is emitted for sterilization.
Further, by forming the light emitting element 20 and the light receiving element 30 on the same substrate, the light receiving and emitting device can be easily formed.

Here, the optical elements such as the light emitting element 20 and the light receiving element 30 generally change their element characteristics depending on the temperature in the usage environment and aging. For example, in the case of the light emitting element 20, even if it is operated with the same electric power, the amount of light emitted may change according to the temperature change of the light emitting element 20. FIG. Further, for example, in the case of the light receiving element 30, the detected value may change even if the same amount of light is received. Therefore, for example, when an optical element is used in a measuring device, a problem may occur that the measurement result changes depending on the element temperature. Therefore, it is preferable that the light emitting/receiving device 1 used as a measuring device corrects the detected value.

As described above, in the light emitting/receiving device 1 , the light emitting element 20 and the light receiving element 30 are formed on the common substrate 2 . Therefore, as shown in FIG. 2, the light emitting/receiving device 1 generates propagating light Lb that is output from the light emitting layer 6 of the light emitting element 20, propagates through the substrate 2, and is received by the light receiving element 30. FIG. Here, the environment in which the propagating light Lb is generated (the operating environment of the light emitting element 20 and the light receiving element 30) is exactly the same as the reflected light La. Unlike the reflected light La, the propagating light Lb is not absorbed by a specific substance or a specific gas, so it is possible to measure the real-time emission intensity including environmental temperature and deterioration of the light emitting element. Here, the state in which the reflected light La is known is, for example, the state in which the reflected light La is zero. For example, it is possible to obtain the detected value of the propagating light Lb from the light receiving element 30 by blocking the light incident surface of the light receiving element with a shutter or blocking the upper surface of the light emitting element with a blackbody surface. Then, the light emitting/receiving device 1 can detect the state of the detection target T with higher accuracy by correcting the measurement of the detection target T based on the emission intensity. As another example, correction of detected values may be performed by a subtraction process. The subtraction process may be, for example, subtracting the detection value of the light receiving element 30 for the propagating light Lb acquired in advance from the detection value of the light receiving element 30 in the measurement of the detection target T. Here, calculation and correction of characteristics can be executed by a processor or the like that acquires detection values of the light receiving element 30 . Also, the temperature characteristics of the light emitting/receiving device 1 may be stored in a memory or the like accessible from the processor. Further, when the light-emitting element is used for sterilization, a correction circuit may be provided to change the power consumption of the light-emitting element based on the detection value of the light-receiving element.

In addition, the light emitting/receiving device 1 does not require another element (for example, a light receiving element for correction) in order to perform the above correction. Therefore, the light emitting/receiving device 1 can be miniaturized.

<Preferred form>
In the light receiving and emitting device 1, the first nitride semiconductor layer 3a contains Al _x Ga _(1-x) N (0<x<1), and the second nitride semiconductor layer 4a contains Al _y Ga _{(1-y )} N (0<x<y<1).

In the light receiving and emitting device 1, the first nitride semiconductor layer 3a preferably contains Al _x Ga _(1-x) N (0.52<x<0.7) and has a film thickness of 50 nm or more and 1000 nm or less. .

In the light emitting/receiving device 1, the second nitride semiconductor layer 4a preferably contains Al _y Ga _(1−y) N (x<y<x+0.3) and has a film thickness of 10 nm or more and 300 nm or less.

In the light emitting/receiving device 1, the nitride semiconductor layer 5 of the first conductivity type preferably has n-type conductivity and contains Al _z Ga _(1-z) N (y≦z<0.85).

The substrate 2 of the light emitting/receiving device 1 is preferably a sapphire substrate or an AlN substrate.

In the light emitting/receiving device 1, the light emitting layer 6 preferably has a multiple quantum well structure containing Al, Ga and N.

<Details about each configuration>
(substrate)
Specific examples of the substrate 2 constituting the light emitting/receiving device 1 of one aspect include sapphire (Al ₂ O ₃ ), Si, SiC, MgO, Ga ₂ O ₃ , ZnO, GaN, InN, AlN, or mixed crystals thereof. and the like.

For example, when using a nitride semiconductor single crystal substrate such as GaN, AlN, AlGaN, or a substrate (template substrate) in which a nitride semiconductor layer such as GaN, AlN, AlGaN is formed on a base material, on the upper side of the substrate 2 The difference in lattice constant from the nitride semiconductor layer to be formed is small, and threading dislocations can be reduced by growing the nitride semiconductor layer in a lattice matching system.

Moreover, from the viewpoint of high versatility, the substrate 2 may be a sapphire substrate. The substrate 2 may be doped n-type or p-type with donor or acceptor impurities.

As a method for manufacturing the substrate 2, a general substrate growth method such as a vapor phase growth method such as a sublimation method or a HVPE method, and a liquid phase growth method can be applied. Also, the thickness of the substrate 2 may be, for example, 100 μm or more and 800 μm or less. Further, the plane orientation includes c-plane (0001), a-plane {11-20}, m-plane {10-10}, etc. More preferably, the c-plane substrate is used.

(First nitride semiconductor layer, third nitride semiconductor layer)
As described above, the first nitride semiconductor layer 3 a and the third nitride semiconductor layer 3 b are formed by separating the nitride semiconductor lower layer 3 formed on the main surface of the substrate 2 . Therefore, the composition of nitride semiconductor lower layer 3 is the composition of first nitride semiconductor layer 3a and third nitride semiconductor layer 3b. Here, the main surface of the substrate 2 means the surface on which the first nitride semiconductor laminate 21 and the second nitride semiconductor laminate 31 are laminated. Here, the main surface of the substrate 2 is not limited to a flat surface (flat surface), and may include unevenness, for example.

The nitride semiconductor lower layer 3 contains Al _x Ga _(1-x) N (0<x<1) as a nitride semiconductor. Here, as described above, “including Al _x Ga _(1-x) N” means that most of the nitride semiconductor lower layer 3 is composed of Al _x Ga _(1-x) N, but other material. For example, when elements other than Al, Ga and N (e.g. group III elements such as In or dopants such as Mg and Si) are included to such an extent that they do not affect the properties of the nitride semiconductor lower layer 3 (about several percent) There is
Al _x Ga _(1-x) N (0<x<1) is Al _x Ga _(1-x) N (0.45<x<1) from the viewpoint of lattice matching with the substrate and the light-emitting layer. is preferred. Furthermore, considering the wavelength as a light receiving element, Al _x Ga _(1-x) N (0.52<x<0.7) is more preferable.
Also, the film thickness of Al _x Ga _(1-x) N is preferably 20 nm or more and 3000 nm or less from the viewpoint of lattice relaxation and the generated carrier amount of the two-dimensional electron gas. From the viewpoint of process, it is more preferably 50 nm or more and 1000 nm or less.
In addition to N, the first nitride semiconductor layer 3a and the third nitride semiconductor layer 3b contain V group elements other than N, such as P, As, and Sb, C, H, F, O, and Mg. , Si, etc. may be mixed, but the present invention is not limited to this.

(Second nitride semiconductor layer, fourth nitride semiconductor layer)
As described above, the second nitride semiconductor layer 4 a and the fourth nitride semiconductor layer 4 b are formed by separating the nitride semiconductor upper layer 4 . Therefore, the composition of nitride semiconductor upper layer 4 is the composition of second nitride semiconductor layer 4a and fourth nitride semiconductor layer 4b. Nitride semiconductor upper layer 4 contains Al _y Ga _(1-y) N (0<x<y<1) as a nitride semiconductor. x is the Al composition ratio in the composition formula of the nitride semiconductor in the nitride semiconductor lower layer 3 .
Al _y Ga _(1-y) N (0<x<y<1) in the light-emitting element 20 is Al _y Ga _(1-y) N (x<y<x+0) from the viewpoint of lattice matching with the substrate and the light-emitting layer. .3). Furthermore, in view of the contact property with the electrode as a light receiving element, Al _y Ga _(1−y) N (x<y<x+0.2) is more preferable.
Also, the film thickness of Al _y Ga _(1-y) N is preferably 5 nm or more and 300 nm or less from the viewpoint of lattice relaxation and the generated carrier amount of the two-dimensional electron gas. From the viewpoint of process, it is more preferably 10 nm or more and 100 nm or less.
Al _y Ga _(1−y) N (0<x<y<1) in the light receiving element 30 is the same as in the light emitting element 20 . On the other hand, the film thickness is preferably 5 nm or more and 100 nm or less from the viewpoint of the amount of carriers generated in the two-dimensional electron gas. From the viewpoint of forming a Schottky barrier by the electrode, the thickness is preferably 10 nm or more and 50 nm or less.
In addition to N, the second nitride semiconductor layer 4a and the fourth nitride semiconductor layer 4b contain V group elements other than N, such as P, As, and Sb, C, H, F, O, and Mg. , Si, etc. may be mixed, but the present invention is not limited to this.

Here, the lattice constant of Al _x Ga _(1−x) N can be calculated by the following equation (1) using Vegard's law.
a _AB = xa _A + (1-x) a _B ... (1)
a _AB in equation (1) is the lattice constant of Al _x Ga _(1−x) N. Also, a _A is the lattice constant of AlN. Also, _aB is the lattice constant of GaN. Here, as a _A and a _B , "S. Strite and H. Morko, GaN, AIN, and InN: A review Journal of Vacuum Science & Technology B 10, 1237 (1992); doi: 10.1116/1.585897" (a _A =3.112 Å, a _B =3.189 Å) can be used.
To find the lattice constant in more detail, it is possible to find it by electron energy loss spectroscopy (TEM-EELS). From the Al composition and Ga composition of each layer obtained by EELS measurement commissioned by the Foundation for the Advancement of Materials Science and Technology (MST), detailed lattice constants of each layer can be determined according to the above Vegard's law.
Alternatively, it can be calculated using X-ray diffraction (XRD). XRD was carried out using a PANalytical X'pert/MRD with a tube at 45 kV/40 mA, a collimated line source using double crystal Ge(220), and an incident solar slit of 0.0. 04°, the detector slit is set to 1/16 mm, and the axis is aligned with respect to the (20-24) plane peak of the AlN substrate. After that, the 2θ/ω scan was performed in the range of 34° to 37°, the measurement interval was 0.02°, and the integration time was 0.3 seconds. The 2θ/ω scan is repeated while changing the ° interval. Qx and Qy are calculated from the above measurements, and the relaxation rate and lattice constant for the substrate are calculated.
As a method for measuring the film thickness of each layer in the substrate and the nitride semiconductor layer, there is a method of using the film thickness observed by slicing the laminate and observing the cross section by TEM (transmission electron microscopy). More specifically, a sample is prepared which is exfoliated to 200 nm with respect to the <11-20> plane. Using Hitachi's HD-2300, the measurement is performed with an applied voltage of 200 kV. The observation range of the cross-sectional image has an observation width of 1 μm, observation is performed at each of three locations, and the average thickness of each layer at the three locations is taken as the film thickness.

As described above, the Al composition ratio y in the composition formula of the nitride semiconductor of the nitride semiconductor upper layer 4 is larger than the Al composition ratio x in the composition formula of the nitride semiconductor of the nitride semiconductor lower layer 3 . Therefore, the second nitride semiconductor layer 4a has a larger lattice constant than the first nitride semiconductor layer 3a. Moreover, the fourth nitride semiconductor layer 4b has a larger lattice constant than the third nitride semiconductor layer 3b.

(First conductivity type nitride semiconductor layer)
The first conductivity type nitride semiconductor layer 5 is a conductive nitride semiconductor layer, and is formed on the nitride semiconductor upper layer 4 (second nitride semiconductor layer 4a). The nitride semiconductor included in the nitride semiconductor layer 5 of the first conductivity type is, for example, Al _z Ga _(1-z) N (0<z<1). Al _z Ga _(1-z) N (0<z<1) is preferably Al _z Ga _(1-z) N (y≦z<1) from the viewpoint of lattice matching with the substrate and the light-emitting layer. . Furthermore, in view of the contact property with the electrode, Al _z Ga _(1-z) N (y≦z<0.85) is more preferable. Also, the film thickness of Al _z Ga _(1-z) N is preferably 300 nm or more and 3000 nm or less from the viewpoint of lattice relaxation and reduction of the resistance component. From the viewpoint of process, it is more preferably 300 nm or more and 1000 nm or less. When y<z, 2DEG occurs also at this interface, which is better from the viewpoint of resistance reduction.
When forming the light-emitting layer 6 from a material corresponding to the bandgap energy in the deep ultraviolet region, it is possible to improve the crystallinity and the light-emitting efficiency. From the viewpoint of realizing high luminous efficiency, the nitride semiconductor included in the first conductivity type nitride semiconductor layer 5 is preferably a mixed crystal of AlN and GaN. In addition to N, the nitride semiconductor of the first conductivity type nitride semiconductor layer 5 contains V group elements other than N, such as P, As, and Sb, and impurities such as C, H, F, O, Mg, and Si. Although it may be mixed, it is not limited to this.

The first conductivity type nitride semiconductor layer 5 and the second conductivity type nitride semiconductor layer 7 are layers of nitride semiconductors having conductivity different from each other. In general, a p-type semiconductor has a deeper acceptor level than an n-type semiconductor, and it is necessary to grow low Al composition AlGaN with a large lattice constant. From the viewpoint of lattice matching, an n-type semiconductor having a lattice constant close to that of the light-emitting layer has better crystallinity than a p-type semiconductor, and has less influence on the light-emitting layer 6 . Therefore, it is preferable that the nitride semiconductor layer 5 of the first conductivity type is n-type and the nitride semiconductor layer 7 of the second conductivity type is p-type.

(Light emitting layer)
The light emitting layer 6 is a nitride semiconductor layer and is formed on the first conductivity type nitride semiconductor layer 5 . The nitride semiconductor included in the light emitting layer 6 is preferably a mixed crystal of AlN and GaN, for example, from the viewpoint of achieving high light emission efficiency. In addition to N, the light-emitting layer 6 may contain V group elements other than N, such as P, As, and Sb, and impurities such as C, H, F, O, Mg, and Si. Moreover, the light emitting layer 6 can have either a quantum well structure or a single layer structure. From the viewpoint of achieving high luminous efficiency, the light emitting layer 6 preferably has at least one well structure.

Further, when the emission wavelength of the light emitting element 20 is to be in the deep ultraviolet region (280 nm or less), the nitride semiconductor included in the light emitting layer 6 preferably contains Al, Ga and N. In addition, from the viewpoint of increasing the luminous efficiency, the light emitting layer 6 has a multiple quantum well structure (MQW) having quantum well layers containing Al, Ga and N and electron barrier layers made of AlN or a mixed crystal containing AlN. is preferred.

(Second conductivity type nitride semiconductor layer)
The second conductivity type nitride semiconductor layer 7 is a conductive nitride semiconductor layer and is formed on the light emitting layer 6 . The nitride semiconductor included in the second conductivity type nitride semiconductor layer 7 is, for example, GaN or AlGaN. In addition to N, the nitride semiconductor of the nitride semiconductor layer 7 of the second conductivity type contains V group elements other than N, such as P, As, and Sb, and impurities such as C, H, F, O, Mg, and Si. It may be mixed. However, as described above, it is preferable that the conductivity of the nitride semiconductor layer 5 of the first conductivity type is n-type and the conductivity of the nitride semiconductor layer 7 of the second conductivity type is p-type.

(electrode)
Among the electrodes 11 and 12 of the light emitting element 20, the n-type electrode (for example, the electrode 12) includes Al, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Co, Rh, Ir, Ni, Metals such as Pd, Pt, Cu, Ag, Au, and Zr, mixed crystals thereof, or conductive oxides such as ITO or Ga ₂ O ₃ can be used. For example, the n-type electrode may use Ti/Al/Ni/Au. In addition, the p-type electrode (for example, the electrode 11) is made of metals such as Ni, Au, Pt, Ag, Rh, Pd, Pt, and Cu, mixed crystals thereof, or conductive oxides such as ITO or Ga ₂ O ₃ etc. can be used. For example, the p-type electrode may use Ni/Au.

The electrodes 13 and 14 of the light receiving element 30 are made of at least Ti, Al, Au, Ni, V, Mo, Hf, Ta, W, Nb, Zn, Ag, Cr, and Zr, which are low contact resistance materials. It can be constructed of materials including three. For example, electrodes 13 and 14 may use V/Al/Mo/Au.

Methods of forming the electrodes 11, 12, 13 and 14 include, but are not limited to, resistance heating vapor deposition, electron gun vapor deposition, sputtering, and the like. Electrodes 11, 12, 13 and 14 may be single layers. Electrodes 11, 12, 13 and 14 may also be laminated. Moreover, the electrodes 11, 12, 13 and 14 may be subjected to heat treatment in an atmosphere of oxygen, nitrogen, air, or the like after the layers are formed.

(Two-dimensional electron gas layer)
The nitride semiconductor lower layer 3 functions as a channel layer, the nitride semiconductor upper layer 4 functions as a barrier layer, and a two-dimensional electron gas layer 8 exists at the interface between the channel layer and the barrier layer. Here, in the light receiving element 30,
Schottky junctions are generated between the nitride semiconductor upper layer 4 and the electrodes 13 and 14 by forming the electrodes 13 and 14 corresponding to the source electrode and the drain electrode from the above materials. Therefore, in the light receiving element 30, the current between the source and the drain in the dark state is reduced. On the other hand, when ultraviolet rays are incident on the nitride semiconductor upper layers 3 and 4, electron-hole pairs are generated in the depletion layer, and the electric field causes the electrons and holes to flow, respectively, so that the two-dimensional electron gas layer 8b and the electrodes resistance is reduced. Thereby, the Schottky junction between nitride semiconductor upper layer 3 and electrodes 13 and 14 disappears. Therefore, a large photocurrent can be obtained when light is incident.

Further, unlike the configuration of the conventional technology, the light emitting device 20 includes the first nitride semiconductor layer 3a and the second nitride semiconductor layer 4a having a larger lattice constant than the first nitride semiconductor layer 3a. Prepare. The light-emitting element 20 has a two-dimensional electron gas layer 8a like the light-receiving element 30 does. The light emitting device 20 also has an ohmic contact (electrode 12) on the first conductivity type nitride semiconductor layer 5 near the two-dimensional electron gas layer 8a. Due to the presence of the two-dimensional electron gas layer 8 , electrons injected through the electrode 12 preferentially flow through the two-dimensional electron gas layer 8 via the first conductivity type nitride semiconductor layer 5 . This is because the two-dimensional electron gas layer has a lower resistance than the nitride semiconductor layer of the first conductivity type, which reduces the lateral resistance and enables the forward voltage Vf of the light emitting element 20 to be reduced. be. In addition, electrons preferentially flow through the two-dimensional electron gas layer, thereby reducing current concentration. Thereby, the light emission distribution is improved, and the light emission intensity of the light emitting element 20 can be increased.

(Light receiving element)
The light receiving element 30 is an MSM (metal-semiconductor-metal) ultraviolet light receiving element. Since the structure is simple, complicated steps are not required in the manufacture of the light receiving element 30, and the layers below the light emitting element 20 (layers close to the substrate 2) can be shared. Further, as described above, the detected value of the light receiving element 30 can be corrected based on the propagating light Lb that propagates through the substrate 2 shared with the light emitting element 20 .

(Light receiving and emitting device)
The light emitting/receiving device 1 can be applied to devices in, for example, the medical/life science field, the environmental field, the industrial/industrial field, the life/home appliance field, the agricultural field, and other fields. The light emitting/receiving device 1 is used for synthesizing/decomposing medicines or chemical substances, sterilizing equipment for liquids/gases/solids (containers, foods, medical equipment, etc.), cleaning equipment for semiconductors, etc., and surface modification equipment for films, glass, metals, etc. , exposure equipment for manufacturing semiconductors, FPDs, PCBs, and other electronic products, printing/coating equipment, adhesion/sealing equipment, transfer/molding equipment for films, patterns, mockups, etc., measurement of banknotes, scratches, blood, chemical substances, etc.・Applicable to inspection equipment.

Examples of liquid sterilizers include automatic ice makers, ice trays and ice storage containers in refrigerators, water supply tanks for ice makers, freezers, ice makers, humidifiers, dehumidifiers, cold water tanks, hot water tanks, and flow paths of water servers. Piping, stationary water purifiers, portable water purifiers, water supply equipment, water heaters, waste water treatment equipment, disposers, waste water traps for toilet bowls, washing machines, dialysis water sterilization modules, peritoneal dialysis connector sterilizers, disaster water storage systems, etc. are listed, but are not limited to these.

Examples of gas sterilizers include air purifiers, air conditioners, ceiling fans, floor or bedding vacuum cleaners, futon dryers, shoe dryers, washing machines, clothes dryers, indoor germicidal lamps, and storage ventilation. Examples include, but are not limited to, systems, shoeboxes, chests of drawers, and the like.

Examples of solid sterilizers (including surface sterilizers) include vacuum packers, belt conveyors, hand tool sterilizers for medical, dental, barber and beauty salon use, toothbrushes, toothbrush cases, chopstick cases, cosmetic pouches, Drain lids, local washes of toilet bowls, toilet bowl lids, etc., but not limited to these.

<Manufacturing method>
The light emitting/receiving device 1 is manufactured through steps of forming each layer on the substrate 2 . This step can be performed, for example, by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD). In FIG. 3, a nitride semiconductor lower layer 3, a nitride semiconductor upper layer 4, a first conductivity type nitride semiconductor layer 5, a light emitting layer 6 and a second conductivity type nitride semiconductor layer 7 are formed in this order on a substrate 2. state. Here, a two-dimensional electron gas layer 8 exists at the interface between the nitride semiconductor lower layer 3 and the nitride semiconductor upper layer 4 .

The light emitting/receiving device 1 is manufactured through a process of removing unnecessary portions of each layer formed on the substrate 2 by etching. This step can be performed, for example, by inductively coupled plasma (ICP) etching. Here, a resist 50 is formed on the required portion (portion to be protected). FIG. 4 shows a state in which each layer formed on the substrate 2 is etched and separated into the light-emitting element 20 portion and the light-receiving element 30 portion. Here, as shown in FIG. 4, a resist 50 is formed on the second conductivity type nitride semiconductor layer 7 in the light emitting element 20 and light receiving element 30 portions. 5 shows a state in which the first conductivity type nitride semiconductor layer 5, the light emitting layer 6, and the second conductivity type nitride semiconductor layer 7 are removed by etching from the light receiving element 30 portion. Moreover, FIG. 6 shows a state in which part of the light emitting layer 6 and the second conductivity type nitride semiconductor layer 7 of the light emitting element 20 is removed by etching.

The light emitting/receiving device 1 is manufactured through steps of forming electrodes 11 , 12 , 13 and 14 . This step can be carried out in a variety of ways, for example by evaporating the metal by electron beam evaporation (EB). FIG. 7 shows a state in which the electrode 11 is formed by depositing metal.

Here, among the layers formed on the substrate 2, the nitride semiconductor layer is an Al raw material containing, for example, trimethylaluminum (TMAl), a Ga raw material containing trimethylgallium (TMGa) or triethylgallium (TEGa), for example, It can be formed using an N source containing ammonia (NH ₃ ).

Light emitting and receiving devices of Examples 1 to 19 and Comparative Examples 1 to 4 having the same layer structure as the light emitting and receiving device 1 of the above embodiment were produced. In other words, the light emitting/receiving devices of Examples 1 to 19 and Comparative Examples 1 to 4 have a light emitting element and a light receiving element on one substrate. The light emitting device includes a first nitride semiconductor layer, a second nitride semiconductor layer, a first conductivity type nitride semiconductor layer, a light emitting layer, a second conductivity type nitride semiconductor layer, and two electrodes. Also, the light receiving element includes a third nitride semiconductor layer, a fourth nitride semiconductor layer and two electrodes.

[Example 1]
A light emitting/receiving device 1 having the structure shown in FIG. 1 was manufactured as follows.

A nitride semiconductor lower layer 3, a nitride semiconductor upper layer 4, a first conductive type nitride semiconductor layer 5, a light emitting layer 6 and a second conductive layer are formed on a substrate 2 containing a sapphire single crystal by metal organic chemical vapor deposition (MOCVD). type nitride semiconductor layers 7 were laminated in this order. Specifically, an AlN buffer layer of 2 μm was formed on a sapphire single crystal substrate using TMAl and NH ₃ . Al _x Ga _(1−x) N (x=0.45) as the first nitride semiconductor lower layer 3 was formed thereon to a thickness of 150 nm using TMAl, TEGa and NH ₃ . Next, Al _y Ga _(1-y) N (y=0.55) was formed to a thickness of 50 nm as the second nitride semiconductor upper layer 4 . Al _z Ga _(1−z) N (z=0.55) is formed with a thickness of 500 nm as the first conductivity type nitride semiconductor layer 5 , and Si is doped by using monosilane (SiH ₄ ) at this time to form an n-type semiconductor. layered. A light-emitting layer 6 composed of Al _0.55 Ga _0.45 N/Al _0.75 Ga _0.25 N was laminated thereon in three cycles so as to have a quantum well layer of 3 nm/barrier layer of 6 nm. 10 nm of p-type Al _0.85 Ga _0.15 N was formed as an electron blocking layer. At this time, Mg was doped using cyclopentadienylmagnesium (Cp ₂ Mg). Finally, Cp ₂ Mg was used to laminate p-type GaN to a thickness of 100 nm as the second conductivity type nitride semiconductor layer 7 . Through this process, the laminate shown in FIG. 3 was obtained. The film thickness in each layer of this laminate was calculated by cross-sectional TEM measurement, and the Al composition was calculated by XRD.

In this lamination step, a light emitting/receiving device was produced from the laminated body obtained by the steps shown in FIGS. Specifically, using an RTA apparatus, a p-type activation process is performed at 900° C. for 5 minutes in a nitrogen atmosphere, and the layered structure on which a photomask using a resist is formed is grown on the substrate using ICP. Etching was performed so as to reach the AlN buffer layer formed thereon, and the light emitting element and the light receiving element were separated. Next, a photomask using a resist was formed again, and only the light receiving element 30 was etched by ICP up to the second nitride semiconductor upper layer 4b. At this time, the thickness of the second nitride semiconductor upper layer 4b was 25 nm from step measurement. A photomask was prepared using a new resist, and the light emitting element 20 was partially etched up to the first conductivity type nitride semiconductor layer 5 . At this time, the film thickness of the exposed portion of the etched first conductivity type nitride semiconductor layer 5 was 480 nm. A photomask using a new resist was formed, and EB vapor deposition was performed on the etched first conductivity type nitride semiconductor layer 5 of the light emitting element 20 and the second nitride semiconductor upper layer 4b of the light receiving element 30 . The electrodes used are V/Al/Ni/Au. The deposited electrode was subjected to alloying treatment at 950° C. for 1 minute in a nitrogen atmosphere using an RTA apparatus. A photomask using a new resist was formed, and EB vapor deposition was performed on the second conductivity type nitride semiconductor layer 7 of the light emitting element 20 . The electrodes used are Ni/Au. The deposited electrode was subjected to alloying treatment at 900° C. for 1 minute in a nitrogen atmosphere using an RTA apparatus. A 10 nm SiO ₂ protective film was formed using plasma Chemical Vapor Deposition (CVD). A window was opened in the SiO ₂ protective film directly above the electrodes 11, 12, 13, and 14, and Ti/Au was vapor-deposited as a pad electrode to obtain a light emitting/receiving device 1.

Thus, the light emitting/receiving device 1 having the structure shown in FIG. 1 was obtained. LED characteristics and sensor characteristics were evaluated for the flip-chip type device. For the evaluation of the LED characteristics, the emission characteristics and driving voltage when current was applied were measured using an integrating sphere and a parameter analyzer. When 350 mA was applied, ultraviolet light irradiated from the back side of the substrate was measured, and the wavelength was 265 nm, and an output of 12 mW was obtained. At this time, the driving voltage was 5.1V. Next, the characteristics of the sensor were evaluated using standard ultraviolet light separated by a filter while the LED was not illuminated. Also at this time, the measurement was performed with the ultraviolet light incident from the back side of the substrate. The wavelength of the ultraviolet light used was 265 nm (half width of 3 nm), and 10 μW/cm ² was used. The photosensitivity calculated from the obtained current value was 10 ⁶ A/W, and the signal/noise (S/N) when not irradiated with ultraviolet light was 10 ⁶ . In addition, when the LED is irradiated under the same conditions as above, the output of the sensor obtained by the LED irradiation light that propagates only inside the substrate in an environment where the reflected light does not enter the sensor (using a shutter or cover) When the voltage (output voltage in open system) was measured, 3 mV was obtained. Since the output voltage was 0.01 mV when the LED was not driven, it became clear that the propagating light could be measured.

[Example 2]
By performing the same steps as in Example 1 on the first nitride semiconductor laminate 21 and the second nitride semiconductor laminate 31 under the conditions shown in Table 1 in detail, Examples 2 to 19, Light receiving and emitting devices 1 of Comparative Examples 1 to 3 were obtained.

From the above results, a good correlation was obtained between the sensor output voltage and the irradiation intensity of the LED when only the propagating light was measured, proving that calibration using the internally propagating light is possible.

(others)
The present disclosure may not be limited to the embodiments and variations described above. Design changes and the like can be added to each embodiment based on the knowledge of those skilled in the art, and aspects with such changes and the like are included in the scope of the present disclosure.

1 light emitting/receiving device 2 substrate 3 nitride semiconductor lower layer 3a first nitride semiconductor layer 3b third nitride semiconductor layer 4 nitride semiconductor upper layer 4a second nitride semiconductor layer 4b fourth nitride semiconductor layer 5 1-conductivity-type nitride semiconductor layer 6 light-emitting layer 7 second-conductivity-type nitride semiconductor layers 8, 8a, 8b two-dimensional electron gas layers 11, 12, 13, 14 electrode 20 light-emitting element 21 first nitride semiconductor laminate 30 Light receiving element 31 Second nitride semiconductor laminate 50 Resist La Reflected light Lb Propagating light T Object to be detected

Claims (6)

a substrate;
a light emitting device formed on the substrate and having a first nitride semiconductor laminate;
a light receiving element formed on the substrate and having a second nitride semiconductor laminate,
The first nitride semiconductor laminate is
a first nitride semiconductor layer of Al _x Ga(1−x)N (0<x<1);
a second nitride semiconductor layer formed on the first nitride semiconductor layer and having Al _y Ga(1-y)N (0<x<y<1);
a first conductivity type nitride semiconductor layer formed on the second nitride semiconductor layer and containing Al and Ga;
a light emitting layer formed on the nitride semiconductor layer of the first conductivity type and containing Al and Ga;
a second conductivity type nitride semiconductor layer formed on the light emitting layer and containing Al and Ga;
two electrodes provided directly on the first conductivity type nitride semiconductor layer and on the second conductivity type nitride semiconductor layer, respectively;
The second nitride semiconductor laminate is
a third nitride semiconductor layer having the same composition as the first nitride semiconductor layer;
a fourth nitride semiconductor layer formed on the third nitride semiconductor layer and having the same composition as the second nitride semiconductor layer;
and two electrodes provided directly on the fourth nitride semiconductor layer.
Light receiving and emitting device. The first nitride semiconductor layer is Al _x Ga(1-x)N (0.52<x<0.7) and has a film thickness of 50 nm or more and 1000 nm or less.
The light emitting/receiving device according to claim 1 . The second nitride semiconductor layer is Al _y Ga(1-y)N (x<y<x+0.3) and has a thickness of 300 nm or less.
The light emitting/receiving device according to claim 1 or 2. the first conductivity type nitride semiconductor layer has n-type conductivity and contains Al _z Ga(1-z)N (y≦z<0.85);
The light emitting/receiving device according to any one of claims 1 to 3. The substrate is a sapphire substrate or an AlN substrate,
The light emitting/receiving device according to any one of claims 1 to 4. The light emitting layer has a multiple quantum well structure containing Al, Ga and N,
The light emitting/receiving device according to any one of claims 1 to 5.

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