JP2000101128A - Gan semiconductor light reception element and its application - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light reception element which has higher sensitivity and has superior resistance with respect to ultraviolet rays. SOLUTION: A stacked matter S, which contains a p-n junction structure via a buffer layer 2 (or directly) and is formed of a GaN material is grown on a crystal substrate 1, and a light reception element is obtained. The element is a back incidence-type element, by using a material through which light L1 which is a reception object passes for the crystal substrate. A buffer layer 2 or a crystal layer above it is set as a photosensitive layer which receives a light L1 and emitting photo luminescence L2. The buffer layer 2 is set as the photosensitive layer. In a p-n junction structure (S1/S2), layers generating carriers associated with optical current by optical excitation are light detection layers (c) and (d). The GaN material which generates carriers associated with an optical current by a light L2 is used for the light detection layers (c) and (d). By causing the layer of a band gap smaller than that of the light detection layers to be prevented from existing between the light detection layers ((c) and (d)), so as to make the light L2 reach the light detection layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a semiconductor photodetector utilizing the photovoltaic effect of a pn junction.

[0002]

2. Description of the Related Art With the increase in density of integrated circuits, reduced projection exposure apparatuses for forming fine circuit patterns include:
The ability to perform finer drawing at higher resolution is required. Therefore, a KrF excimer laser device (wavelength 248 nm) is used as a laser light source for drawing.
Also, switching to an ArF excimer laser device (wavelength 193 nm) is being studied.

In the above-described reduced projection exposure apparatus, a part of the laser beam is received by a light receiving element, and the output fluctuation is monitored. Examples of the light receiving element include a photodiode (PD) using a Si-based semiconductor material. However, if the laser light is a light having intense energy of a short wavelength such as 248 nm or 193 nm, the deterioration of the Si-based PD conventionally used becomes remarkable, and unless it is frequently replaced with a new one. It becomes the use situation which does not become.

[0004]

On the other hand, JP-A-7-28
Various light-receiving elements using a GaN-based semiconductor material, such as “Gallium nitride-based compound semiconductor light-receiving element” in JP-A-8334, have been devised. However, as described in the publication, the light to be received by the GaN-based light receiving element is 365
It is a long wavelength light of nm or more.

In the GaN-based light receiving element described in the publication, the light to be received, which is irradiated from above, directly reaches the light detection layer (the In _X Ga ₁ -XN light receiving layer in the publication) to receive the light. It is assumed that. Therefore, the layer above the light detection layer is recognized only as a window layer for transmitting light to be received. This means that the light to be received is 3
It is clear from the fact that the light is limited to long wavelength light of 65 nm or more. That is, light having a wavelength shorter than 365 nm is
Ga used as a contact layer on the outer layer of the laminate
It is only recognized that it is absorbed by N and cannot reach the photodetection layer directly enough.

As described above, since the conventional GaN-based light receiving element has only the idea of causing the light to be received directly to reach the light detection layer, the outer layer is provided with a band gap larger than the energy of the light to be received. No conditions or configurations have been taken into consideration so as to preferably receive light having an energy larger than that of the outer layer.

An object of the present invention is to provide a semiconductor light receiving element which can receive light of a shorter wavelength and has excellent resistance to ultraviolet rays by a new structure.

It is another object of the present invention to provide a method for detecting light using the light receiving element according to the present invention.

[0009]

The GaN-based semiconductor light receiving device of the present invention has the following features. (1) A light receiving structure having a structure in which a GaN-based crystal layer including a pn junction structure is formed on a crystal substrate via a buffer layer, and a p-side electrode and an n-side electrode are formed on the stacked body. In the device, the crystal substrate is made of a material through which light to be received can be transmitted, and the buffer layer is a light-sensitive layer made of a material that receives light to be received and emits photoluminescence light. A layer that generates carriers related to photocurrent by photoexcitation is a photodetection layer. The photodetection layer is made of a GaN-based material that generates carriers related to photocurrent by the photoluminescence light, and includes a photodetection layer and a photosensitive layer. A GaN-based semiconductor light-receiving element characterized in that a layer having a band gap smaller than the band gap of the light detection layer does not exist between the GaN-based semiconductor light receiving element.

(2) The GaN-based semiconductor light-receiving device according to (1), wherein the material of the buffer layer is a GaN-based material.

(3) A laminated body composed of a GaN-based crystal layer including a pn junction structure is formed on a crystal substrate via a buffer layer or directly, and a p-type side electrode and an n-type side electrode are formed thereon. A light-receiving element having a formed structure, wherein the crystal substrate and the buffer layer are made of a material through which light to be received can be transmitted, and a light-receiving object is provided between the crystal substrate and the light detection layer in the pn junction structure. A light-sensitive layer made of a GaN-based crystal that receives light and emits photoluminescence light is provided. In the pn junction structure, a layer that receives light and generates carriers related to photocurrent is a light detection layer. The layer is made of GaN that generates carriers related to photocurrent by receiving the photoluminescence light.
A GaN-based semiconductor light-receiving device, comprising a system material, wherein a layer having a band gap smaller than the band gap of the light detection layer does not exist between the light detection layer and the photosensitive layer.

(4) A structure in which the pn junction structure is a hetero junction structure, and an intermediate layer made of a GaN-based crystal exists between the photodetection layer and the photosensitive layer. [Energy of photoluminescence light] <The GaN according to the above (1) or (3), wherein a combination of the material of the intermediate layer and the material of the photosensitive layer is selected so as to satisfy [[band gap of the intermediate layer]].
Series semiconductor light receiving element.

(5) [Band gap of light detection layer] <
The combination of the material of the photodetection layer, the material of the intermediate layer, and the material of the photosensitive layer is such that [energy of photoluminescence light] ≦ [band gap of the photosensitive layer] <[band gap of the intermediate layer]. The selected G according to (4) above
aN-based semiconductor light receiving element.

(6) The GaN-based semiconductor light-receiving element according to any one of (1) to (5), wherein the light to be received is light having energy larger than the band gap of the photosensitive layer.

The detection method of the present invention has the following features. (7) The GaN-based semiconductor light-receiving element according to any one of (1) to (6) above, wherein light having an energy equal to or larger than the band gap of a photosensitive layer provided in the GaN-based semiconductor light-receiving element is received. A method for detecting light, comprising: causing light to enter a light-sensitive layer, generating photoluminescence light in the light-sensitive layer, and detecting the photoluminescence light in a light detection layer.

(8) The detection method according to the above (7), wherein light having an energy larger than the band gap of the photosensitive layer is used as light to be received.

[0017]

The light receiving element according to the present invention detects the light reception by extracting the electromotive force of the light to be received by using a pn junction. The basic structure of the element is similar to solar cells, etc.
It has a pn junction structure and ohmic electrodes on both sides.

The first feature of the light receiving element according to the present invention is that it has a structure of a type (back-illuminated type) which receives light from the back side of the crystal substrate and receives light. Therefore, the material of the crystal substrate is a material through which light to be received can be transmitted. With the back-illuminated structure, the following two functions can be obtained simultaneously. Both contribute to the improvement of sensitivity. Since the electrode does not block the light to be received, the limited incident area can be used to the maximum, and the photocurrent can be generated more efficiently. Since there is no need to consider the incidence of light when forming the electrodes, the area occupied by the electrodes can be expanded to the maximum with respect to the electrode installation surface, and the generated photocurrent can be taken out more efficiently. Become.

The second feature of the light receiving element according to the present invention resides in the presence of a photosensitive layer. That is, the light to be received does not directly reach the light detection layer, but is once received by the light-sensitive layer, converted into photoluminescence light (hereinafter, also referred to as PL light) by the layer, and the PL light is converted to the light detection layer. This is a feature of detecting this by reaching. For this purpose, the relationship between the energy of the light to be received, the band gap of the photosensitive layer, and the band gap of the light detecting layer is specified, and if a layer exists between the photosensitive layer and the light detecting layer, the layer is determined. Is specified, and the PL light reaches the photodetection layer.

In the case of a GaN-based laminate having a pn junction structure, it is preferable that the upper portion of the laminate be p-type and the lower portion (that is, the photosensitive layer side) be n-type, for reasons of production relating to conduction type formation. On the other hand, some GaN-based materials (such as InGaN) emit strong PL light, but some are easier to form as n-type. Therefore, the present invention has an advantage that a GaN-based material that emits such strong PL light can be easily used as the photosensitive layer.

Further, the present invention proposes a mode in which a buffer layer is used as a photosensitive layer by utilizing a back-illuminated structure when providing a photosensitive layer. The buffer layer is relatively easy to form as compared with the crystal layer.

In this specification, the p of the light receiving element according to the present invention is
In the n-junction structure, a “layer that generates carriers related to photocurrent by photoexcitation” is called a photodetection layer. Here, “optical excitation” is excitation by PL light as described above. Further, the “carrier related to the photocurrent” is a carrier that drifts in the depletion layer and becomes a photocurrent. Such carriers include those generated inside the depletion layer as well as those generated outside the depletion layer and capable of reaching the edge of the depletion layer. Therefore, the light detection layer includes the depletion layer itself and a region within the carrier diffusion length from the edge of the depletion layer. However, the light detection layer does not always include the entire depletion layer. As described below, as an intermediate layer, even if it is a depletion layer, if the PL light is transmitted through the heterojunction structure, that part is not included in the photodetection layer.

The light receiving element of the present invention has a mode in which an intermediate layer made of a GaN-based crystal exists between the photosensitive layer and the light detecting layer. For example, in the example of FIG. 1, it is assumed that the pn junction (the n-type layer S1 / p-type layer S2) is a hetero junction and the depletion layers are spread as b and c. The buffer layer 2 also serves as the photosensitive layer. In order to make the PL light L2 preferably reach the light detection layer, it is preferable that the light L2 is transmitted through the n-type layer S1 as a layer having a band gap larger than the energy of the light L2. The depletion layer b extending to the layer S1 is also transmitted. So in that case,
The light detection layer is a combination of the depletion layer c and the region d within the diffusion length of the carrier above the depletion layer c. And the depletion layer b
Is an intermediate layer.

In the example of FIG. 1, when the pn junction is a homo junction, the entire depletion layer (b, c) becomes a layer that can be excited by PL light. Therefore, the light detection layer
This is a layer (a, b, c, d) in which the entire depletion layer and the regions a and d within the carrier diffusion length extending on both sides thereof are combined. In addition, the intermediate layer in the example of FIG. 1 is the remaining part except the part (a, b) of the light detection layer from the layer S1. The middle layer is
Any number of additional layers may be added between the layer S1 and the photosensitive layer.

A method of detecting light using the light receiving element of the present invention,
The magnitude relation of the band gap from the light to be received to the light detection layer will be described with reference to the example of FIG. In FIG. 1, pn
The junction is a heterojunction, the photodetection layer is (c + d), the intermediate layer is the entire layer S1, and the photosensitive layer is the buffer layer 2. The light L1 to be received passes through the crystal substrate 1 and reaches the photosensitive layer. [Band gap of photosensitive layer] ≦ [Energy of light to be received]. The photosensitive layer absorbs the light L1 to be received, and emits the PL light L2 by a transition between bands or a transition between impurity levels. That is, [PL light energy] ≦ [band gap of photosensitive layer]. The PL light reaches the photodetection layer and generates carriers. That is, [band gap of photodetecting layer] ≦ [energy of PL light]. The carriers drift in the depletion layer and become photocurrents, and light reception is detected.

When an intermediate layer exists as shown in FIG.
[Energy of L light] <[Band gap of intermediate layer] is preferable, whereby PL light can reach the photodetection layer without being absorbed. The generation of carriers by light absorption means that electrons in the valence band are excited in the conduction band, and holes are generated in the valence band. Since the bottom of the conduction band occupies few places of electrons, PL light having energy equal to the band gap cannot generate a sufficient amount of carriers (that is, absorption is small). On the other hand, in the case of PL light having an energy larger than the band gap, electrons can be excited also at a position above the bottom of the valence band of the photodetection layer, so that the amount of generated carriers increases (that is, the amount of generated carriers). Large absorption). Therefore, from the point of causing the PL light to reach the photodetection layer without loss, generating more carriers, and increasing the sensitivity, [bandgap of the photodetection layer] <[energy of photoluminescence light] ≦ [photosensitivity Layer band gap)
<[Band gap of intermediate layer] is most preferable. For the same reason, it is preferable that [band gap of photosensitive layer] <[energy of light to be received].

In the example shown in FIG. 1, when the pn junction structure is a homojunction structure, [band gap of the light detection layer] = [band gap of the intermediate layer], the PL light is also absorbed by the intermediate layer. Will be. However, by setting the absorption coefficient of the PL light in the intermediate layer to an appropriate value, the PL light can reach the light detection layer. Also, from such a viewpoint, even if there is an intermediate layer that satisfies [band gap of intermediate layer] <[band gap of light detection layer], it is possible to cause PL light to reach the light detection layer. However, from the viewpoint of seeking a light-receiving element with higher sensitivity, the present invention provides such an intermediate layer (ie,
A layer having a band gap smaller than the band gap of the light detection layer is not provided. The absorption coefficient indicates the degree of light absorption. The absorption coefficient has wavelength dependence, and when the light energy is equal to or larger than the band gap of the semiconductor, the absorption coefficient increases sharply in the direct transition type semiconductor and increases gradually in the indirect transition type semiconductor.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a light-receiving element according to the present invention has an n-type crystal layer S1, a buffer layer on a crystal substrate 1 (or directly). A p-type crystal layer S2 is sequentially crystal-grown to form a stacked body S, on which a p-side electrode Q1 and an n-side electrode Q2 are provided to form a light receiving element. All the crystal layers constituting the stacked body S are GaN
It consists of a system material. The photosensitive layer is provided between the crystal substrate and the photodetection layer, and may be provided either as a buffer layer as shown in FIG. 1 or as a GaN-based crystal layer as shown in FIG.

Although there is no limitation on the vertical direction of the pn junction, as described in the description of the operation, an embodiment in which the crystal substrate side is an n-type is preferable in terms of manufacturing. In the examples of FIGS. 1 and 2, the upper layer side is p-type, and the p-type ohmic electrode Q1 is provided on the uppermost layer of the multilayer body S, and the n-type layer is partially exposed, and the n-type layer is exposed on the surface. The ohmic electrode Q2 on the side is provided. Hereinafter, the present invention will be described with a similar electrode structure with the upper layer side being p-type.

The material of the crystal substrate may be any material that can grow a GaN-based material and that can transmit light to be received. For example, sapphire, quartz, SiC and the like can be mentioned. Above all, sapphire C surface, A surface, 6H
-SiC substrates, particularly C-plane sapphire substrates, are preferred.

The wavelength range of light to be received by the device according to the present invention is determined by the band gap of the material of the photosensitive layer. In the present invention, there is an embodiment in which the buffer layer is used as a light-sensitive layer.
It is preferable to use an aN-based material. Therefore, it is preferable to always use a GaN-based material for the light-sensitive layer, and the light to be received at this time is light having a shorter wavelength than red light (wavelength around 656 nm).

Among the light to be received, ultraviolet rays, particularly, a wavelength of 248 nm (KrF excimer laser) and a wavelength of 193 nm are used.
Since nm (ArF excimer laser) is light having intense energy, there are many problems for conventional devices. By using a GaN-based material for receiving such ultraviolet rays, an excellent light-receiving element having improved ultraviolet resistance can be obtained as compared with a conventional PD or the like using a Si-based semiconductor material.

It is preferable to use a GaN-based material for the light-sensitive layer. However, if the material composition is made closer to InN, the range of the light to be received is changed to red light (wavelength 656n) toward the longer wavelength side.
m), but at the same time a PL with low energy
Since light is emitted, there is less room for selecting a material for the light detection layer. Conversely, the material used for the photosensitive layer is AlN
, The boundary where light can not be received approaches the vicinity of the wavelength of 200 nm, and the light to be received is limited to light having a shorter wavelength.
Light will be emitted, leaving less room for choice of intermediate layer material that will preferably transmit it.

In view of the above, the material of the photosensitive layer is InG
It is preferable to select from aN to GaN to AlGaN in consideration of a combination with a material of another layer. Among these preferable materials, GaN is a preferable material because it is easy to increase the quantum efficiency of photoluminescence light by doping impurities (Mg, Si, etc.) and has excellent environmental resistance. Therefore, when the material of the photosensitive layer is GaN, G
Light having an energy equal to or greater than the band gap of aN is a preferable light to be received. In particular, light having a higher energy in terms of absorption coefficient, that is, light having a wavelength shorter than 365 nm is a preferable light to be received.

When the buffer layer is used as a photosensitive layer,
The thickness of the buffer layer is a thickness that can serve as a buffer layer,
Considering the thickness capable of emitting more intense PL light as the photosensitive layer, the preferred range is about 10 nm to 500 nm.

In a case where a light-sensitive layer is separately provided on the buffer layer, it is preferable to use a material having a sufficiently large band gap as a material of the buffer layer so that light to be received can be transmitted. However, if light having energy higher than that of the material of the buffer layer enters, the buffer layer responds and emits unintended PL light. However, unintended PL light is absorbed by the original light-sensitive layer, so that the secondary PL light emitted is weak and can be substantially ignored.

As a method of forming the buffer layer, a method used for forming a conventional buffer layer may be used.
E, CBE, GS-CBE, sputtering and the like. In particular, it is preferable to use the same method as the method of growing the GaN-based crystal layer grown on the buffer layer.

As a method of growing the GaN-based crystal layer grown on the buffer layer, HVPE, MOCVD, MBE and the like can be mentioned, but MOCVD and MBE are preferable because a heterojunction structure can be manufactured with good control.

The pn junction structure is not limited to a two-layer pn junction structure such as a homo junction or a hetero junction as shown in FIG.
A structure in which an i-layer is interposed between a p-type layer and an n-type layer may be used, or various stacked structures such as a double hetero junction structure may be used.

In the case where the pn junction structure is a hetero junction structure, if the n-type layer is an intermediate layer, the band gap of the n-type layer is changed to the other p-type as described in the description of the operation.
Preferably, it is larger than the mold layer. In the case where the pn junction structure is a hetero junction structure, the n-type layer may be a photosensitive layer. In the case of this embodiment, the band gap of the n-type layer is considered from the idea of the present invention that the light to be received is not converted to PL light by the light-sensitive layer to reach the light detection layer without directly reaching the light detection layer. Is preferably larger than the other p-type layer.

The GaN-based material referred to in the present invention has the formula In _X
Ga _Y Al _Z N (0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ Z ≦
1, X + Y + Z = 1). As described in the above description, the GaN-based material according to the above equation is considered in consideration of the band gap so that PL light is emitted from the photosensitive layer and reaches the light detection layer to generate carriers. May be selected and combined from among the materials of each layer. Although there are many examples of combinations of materials, one example is shown below.

As in the embodiment shown in FIG. 1, when the buffer layer 2 also serves as a photosensitive layer and the pn junction structure is a heterojunction structure, the combination of materials (photosensitive layer 2 / n-type layer S1 / p-type layer) S2) is (In _0.1 Ga _0.9 N / GaN / In _0.2
Ga _0.8 N), (Al _0.05 Ga _0.95 N / Al _0.1 Ga
_0.9 N / GaN). When the pn junction structure is a homo junction structure, the material of the n-type layer S1 is the material of the p-type layer S2, and the combination of the materials (the photosensitive layer 2 / the n-type layer S1) is (GaN / InGaN), Al _0.1 Ga
_0.9 N / GaN) and (AlGaN / InGaN).

As shown in FIG. 2, the photosensitive layer is formed of a crystal layer S
In the case where the buffer layer is separately provided as 1, for example, a combination of the above materials may be used for the buffer layer using AlN or the like that transmits light to be received.

In the light-receiving element of the present invention, light that passes through the photosensitive layer and directly reaches the photodetection layer and is excited (referred to as direct excitation light) is not the object of detection. Is done. However, when the light receiving element of the present invention is actually used, there is usually no problem because the light receiving element is normally used under the condition that only the light to be received is irradiated.

The light receiving element of the present invention may be provided with a filter layer for limiting the wavelength range of the light to be received. The filter layer may be used not only for limiting the range of the light to be received itself but also for cutting light other than the light to be received. For example, the direct excitation light is cut, and only the light to be received is selected. The position of the filter layer may be either on the outside world side or on the light detection layer side with respect to the photosensitive layer. When the excitation light is cut directly, the excitation light may be provided on the incident surface of the crystal substrate to transmit the light to be received, or may be provided between the photosensitive layer and the light detection layer to transmit only the PL light.

The method for detecting light according to the present invention is a method for detecting light having an energy greater than or equal to the band gap of the photosensitive layer, and particularly larger than the band gap of the photosensitive layer, using the light receiving element according to the present invention. is there. According to this method, light having higher energy can be detected without being restricted by the band gap of the window layer as in the related art. For example, if the photosensitive layer is GaN,
Light having a wavelength shorter than 365 nm is a preferable light to be received. This is completely different from the conventional light detection method using a light receiving element that detects only light transmitted through the window layer.

[0047]

EXAMPLE 1 In this example, a light receiving element having a structure shown in FIG. 3 was manufactured in a mode in which a buffer layer also serves as a photosensitive layer. The photosensitive layer is In _0.1 Ga _0.9 N, and the light detecting layer is In _0.8 Ga _0.2 N
It is.

[Formation of Buffer Layer (Photosensitive Layer)] A sapphire C-plane substrate was used as the crystal substrate 1 and MOCVD was used.
In a nitrogen atmosphere at 500 ° C., a thickness of 40 n
m In _0.1 Ga _0.9 N buffer layer 2 was formed.

[Formation of Laminated Structure S] The temperature was raised to 1000 ° C., and a hydrogen atmosphere was used.
The N layer S1 was grown at 3 μm. Further, an n-type In _0.2 Ga _0.8 N layer S
2 was grown 0.1 μm. Further, a p-type GaN layer S3 was grown to a thickness of 0.5 μm in a hydrogen atmosphere and biscyclopentadienyl magnesium as a dopant to form a pn junction structure. Thereafter, the atmosphere gas was switched to nitrogen, and the temperature was gradually cooled to room temperature.

In this embodiment, the conductivity type of the In _0.2 Ga _0.8 N layer S2 is n-type. However, the stacked structure of FIG. 3 may be undoped or p-type. Although the interface of the pn junction is different, in each case, the n-type GaN layer S1 is an intermediate layer, and the light detection layer exists in the InGaN layer S2.

[Formation of Electrode] As shown in FIG. 3, the layer S3 and the layer S2 are partially removed by dry etching to partially expose the upper surface of the n-type layer S1, and the n-side electrode is formed on the surface. Q2 was provided, and a p-side electrode Q1 was provided on the upper surface of the remaining p-type layer S3 to provide a light receiving element.

[Evaluation of Performance] This light-receiving element was mounted on a stem base and the sensitivity was measured.
3A / W sensitivity to m light (ArF), wavelength 256n
2A / W sensitivity to m light (KrF), wavelength 325
It exhibited a sensitivity of 2 A / W for nm light (HeCd). However, for light having a wavelength of 390 nm, 0.2 A /
The sensitivity was reduced with W, and no sensitivity was exhibited for blue light of 450 nm.

As described above, the photosensitive layer In _0.1 Ga
_{By using a combination of 0.9} N and a light detection layer (In _0.8 Ga _0.2 N), a light-receiving element having no sensitivity to visible light as described above was obtained. When the life was measured by injecting pulsed light having an ArF wavelength of 193 nm, 1 × 10 ¹⁰
No decrease in sensitivity was observed in the single pulse, indicating that the pulse had excellent resistance to ultraviolet light having a short wavelength.

Example 2 In this example, as shown in FIG. 2, a light receiving element in which a photosensitive layer was independently provided as a crystal layer on a buffer layer was manufactured. The photosensitive layer is Al _0.05 Ga _0.95 N, and the light detecting layer is G
aN.

[Formation of Buffer Layer] Using a sapphire C-plane substrate as the crystal substrate 1, MOCVD, a nitrogen atmosphere,
At 500 ° C., an AlN buffer layer 2 having a thickness of 40 nm was formed on the substrate 1.

[Formation of Laminated Structure S] The temperature was raised to 1000 ° C., and a hydrogen atmosphere was used.
_{A 0.05} Ga _0.95 N layer S1 was grown 0.1 μm. This layer S1 is a photosensitive layer. Further, the n-type Al _0.2 Ga _0.8 N layer S2 is
μm was grown. This layer S2 is an intermediate layer. further,
A p-type GaN layer S3 was grown to a thickness of 0.5 μm in a hydrogen atmosphere with a dopant of biscyclopentadienyl magnesium to form a pn junction structure. A light detection layer exists in the p-type GaN layer S3. Thereafter, the atmosphere gas was changed to nitrogen, and the temperature was gradually cooled to room temperature. Then, an electrode was formed in the same manner as in Example 1 to obtain a light receiving element.

[Evaluation of Performance] When the sensitivity of this light receiving element was measured in the same manner as in Example 1, the sensitivity was 3 A / W with respect to 193 nm light (ArF), and with respect to 256 nm light (KrF). And showed a sensitivity of 2 A / W. However, for 325 nm wavelength light (HeCd), 0.5 A
/ W, the sensitivity decreased, and no sensitivity was exhibited for light having a wavelength of 390 nm. As described above (photosensitive layer Al _0.05 Ga
_0.95 N, photodetection layer GaN)
As compared with Example 1, a light-receiving element in which the boundary area of sensitivity / insensitivity was further shifted to the shorter wavelength side was obtained. ArF wavelength 1
The resistance to 93 nm pulsed light was the same as in Example 1.

[0058]

As described above, the light-receiving element of the present invention is provided with a light-sensitive layer as a type in which light is incident from the back side of the substrate. Since light can be generated and the area occupied by the electrodes can be increased to the maximum, high sensitivity can be obtained. The light-receiving element of the present invention can receive light of wavelengths in the red to ultraviolet range, but has excellent resistance to ultraviolet light by being made of a GaN-based material.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a light receiving element of the present invention.

FIG. 2 is a diagram showing another configuration example of the light receiving element of the present invention.

FIG. 3 is a diagram showing another configuration example of the light receiving element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal substrate 2 Buffer layer (photosensitive layer) L1 Light to be received L2 Photoluminescence light S Stack S1 n-type layer S2 p-type layer Q1 p-type side electrode Q2 n-type side electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Tadomo 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Cable Industry Co., Ltd. Itami Works (72) Inventor Yoichiro Ouchi 4-3-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Inside Electric Wire Industry Co., Ltd. Itami Works (72) Inventor Masahiro Koto 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Electric Wire Co., Ltd. Itami Works (72) Inventor Kazumasa Hiramatsu 1-4-4-2 Shibata, Yokkaichi-shi, Mie Prefecture (72) Inventor Hiroshi Hamamura 1-1-10 Asamizodai, Sagamihara City, Kanagawa Prefecture Inside Nikon Sagamihara Works (72) Inventor Sumito Shimizu 1-6-3 Nishioi, Shinagawa-ku, Tokyo Nikon Oi Works F Terms (reference) 5F049 AA03 AA20 AB07 BA01 BB10 CA04 DA02 EA07 GA01 GA03 LA05

Claims (8)

[Claims] 1. A semiconductor device, comprising: a buffer layer on a crystal substrate;
A light receiving element having a structure in which a stacked body composed of a GaN-based crystal layer including an n-junction structure is formed, and a p-side electrode and an n-side electrode are formed thereon, wherein the crystal substrate transmits light to be received. The buffer layer is a light-sensitive layer made of a material that emits photoluminescence light in response to light to be received, and a layer that generates carriers related to photocurrent by photoexcitation in the pn junction structure. A photodetection layer comprising a GaN-based material that generates carriers related to photocurrent by the photoluminescence light, and a band smaller than a band gap of the photodetection layer between the photodetection layer and the photosensitive layer. A GaN-based semiconductor light receiving element, wherein a gap layer does not exist. 2. The GaN-based semiconductor light receiving device according to claim 1, wherein the material of the buffer layer is a GaN-based material. 3. A laminated body comprising a GaN-based crystal layer including a pn junction structure is formed on a crystal substrate via a buffer layer or directly, and a p-side electrode and an n-side electrode are formed thereon. The crystal substrate and the buffer layer are made of a material through which the light to be received can pass, and the light to be received is provided between the crystal substrate and the light detection layer in the pn junction structure. GaN that emits photoluminescence light in response to light
A light-sensitive layer made of a system crystal is provided. In the pn junction structure, a layer that receives light and generates carriers related to a photocurrent is a light detection layer, and the light detection layer receives the photoluminescence light. It is made of a GaN-based material that generates carriers related to photocurrent, and is characterized in that there is no layer having a band gap smaller than the band gap of the light detection layer between the light detection layer and the light sensitive layer. GaN based semiconductor light receiving element. 4. The pn junction structure is a hetero junction structure,
A structure in which an intermediate layer made of a GaN-based crystal exists between the light detection layer and the photosensitive layer, wherein the energy of the photoluminescence light is smaller than the band gap of the intermediate layer. 4. The GaN-based semiconductor light receiving device according to claim 1, wherein a combination of a material and a material of the photosensitive layer is selected. 5. The photodetecting layer material and the photodetecting layer material such that [bandgap of the photodetecting layer] <[energy of photoluminescence light] ≦ [bandgap of the photosensitive layer] <[bandgap of the intermediate layer]. The GaN-based semiconductor light receiving device according to claim 4, wherein a combination of a material for the intermediate layer and a material for the photosensitive layer is selected. 6. A light receiving object light having energy larger than a band gap of a photosensitive layer.
5. The GaN-based semiconductor light-receiving element according to any one of 5. 7. The GaN according to claim 1,
Using a GaN-based semiconductor light-receiving element, light having an energy equal to or greater than the band gap of the light-sensitive layer provided in the GaN-based semiconductor light-receiving element is incident on the light-sensitive layer as light to be received, and photoluminescence light is generated in the light-sensitive layer. And detecting the photoluminescence light in a photodetection layer. 8. The detection method according to claim 7, wherein light having energy larger than the band gap of the photosensitive layer is used as light to be received.