KR102324939B1 - Semiconductor device - Google Patents

Abstract

Examples include substrates; a buffer layer disposed on the substrate; a filter layer disposed on the buffer layer; a first conductivity-type first semiconductor layer disposed on the filter layer; a light absorption layer disposed on the first conductivity type first semiconductor layer; a first conductivity-type second semiconductor layer disposed on the light absorption layer; an amplification layer disposed on the first conductivity-type second semiconductor layer; and a second conductivity-type semiconductor layer disposed on the amplification layer, wherein the buffer layer includes a first layer including AlGaN, wherein the first layer includes a first surface disposed closest to the substrate and the Disclosed is a semiconductor device comprising a second surface disposed closest to the filter layer, wherein the first surface has an Al composition greater than that of the second surface.

Description

Semiconductor device {SEMICONDUCTOR DEVICE}

The embodiment relates to a semiconductor device.

A semiconductor device including a compound such as GaN or AlGaN has many advantages, such as having a wide and easily adjustable band gap energy, and thus can be used in various ways as a light emitting device, a light receiving device, and various diodes.

In particular, light emitting devices such as light emitting diodes or laser diodes using group 3-5 or group 2-6 compound semiconductor materials of semiconductors have developed red, green, and Various colors such as blue and ultraviolet light can be realized, and efficient white light can be realized by using fluorescent materials or combining colors. , safety and environmental friendliness.

In addition, when a light receiving device such as a photodetector or a solar cell is manufactured using a semiconductor group 3-5 or group 2-6 compound semiconductor material, a photocurrent is generated by absorbing light in various wavelength ranges through the development of the device material. This makes it possible to use light of various wavelength ranges from gamma rays to radio wavelengths. In addition, it has advantages of fast response speed, safety, environmental friendliness, and easy adjustment of device materials, so it can be easily used for power control or ultra-high frequency circuits or communication modules.

Therefore, the semiconductor device can replace a light emitting diode backlight, a fluorescent lamp or an incandescent light bulb that replaces a cold cathode fluorescence lamp (CCFL) constituting a transmission module of an optical communication means and a backlight of a liquid crystal display (LCD) display device. The application is expanding to white light emitting diode lighting devices, automobile headlights and traffic lights, and sensors that detect gas or fire. In addition, the application of the semiconductor device may be extended to high-frequency application circuits, other power control devices, and communication modules.

In particular, in the case of a light receiving element, since a photocurrent is generated by absorbing light of a predetermined wavelength band, the wavelength band of absorbed light may be increased due to an electric field that varies according to the magnitude of the bias. Accordingly, in order to improve sensitivity to light having a predetermined wavelength, it is necessary to reduce a wavelength band according to a changing electric field.

The embodiment provides a semiconductor device having improved responsiveness and transmittance.

The problem to be solved in the embodiment is not limited thereto, and it will be said that the purpose or effect that can be grasped from the solving means or embodiment of the problem described below is also included.

A semiconductor device according to an embodiment includes a substrate; a buffer layer disposed on the substrate; a filter layer disposed on the buffer layer; a first conductivity-type first semiconductor layer disposed on the filter layer; a light absorption layer disposed on the first conductivity type first semiconductor layer; a first conductivity-type second semiconductor layer disposed on the light absorption layer; an amplification layer disposed on the first conductivity-type second semiconductor layer; and a second conductivity-type semiconductor layer disposed on the amplification layer, wherein the buffer layer includes a first layer including AlGaN, wherein the first layer includes a first surface disposed closest to the substrate and the and a second surface disposed closest to the filter layer, wherein the first surface has an Al composition greater than that of the second surface.

The Al composition of the buffer layer may decrease linearly from the first surface to the second surface.

The Al composition of the buffer layer may be gradually decreased from the first surface toward the second surface.

The first layer may have a band gap energy greater than a band gap energy of the filter layer and a band gap energy of the light absorption layer.

The buffer layer may include a second layer between the first layer and the substrate, and the second layer may include AlN.

The Al composition of the first surface may be 60%, and the Al composition of the second surface may be 20%.

The amplification layer may include AlGaN, and the Al composition may be greater than 0% and less than 20%.

The light absorption layer may include a first light absorption layer including InGaN or AlGaN; and a second light absorption layer disposed on the first light absorption layer, wherein the second light absorption layer may have an In composition of 2% to 5%.

A sensor according to an embodiment includes a housing; a first semiconductor element disposed in the housing and emitting ultraviolet light; and a second semiconductor device disposed in the housing, wherein the second semiconductor device includes: a substrate; a buffer layer disposed on the substrate; a filter layer disposed on the buffer layer; a first conductivity-type first semiconductor layer disposed on the filter layer; a light absorption layer disposed on the first conductivity type first semiconductor layer; a first conductivity-type second semiconductor layer disposed on the light absorption layer; an amplification layer disposed on the first conductivity-type second semiconductor layer; and a second conductivity-type semiconductor layer disposed on the amplification layer, wherein the buffer layer includes a first layer including AlGaN, wherein the first layer includes a first surface disposed closest to the substrate and the and a second surface disposed closest to the filter layer, wherein the first surface has an Al composition greater than that of the second surface.

An electronic product according to an embodiment includes a case; a sensor disposed within the case; and a control unit communicating with the sensor, wherein the sensor includes: a housing; a first semiconductor element disposed in the housing and emitting ultraviolet light; and a second semiconductor device disposed in the housing, wherein the second semiconductor device includes: a substrate; a buffer layer disposed on the substrate; a filter layer disposed on the buffer layer; a first conductivity-type first semiconductor layer disposed on the filter layer; a light absorption layer disposed on the first conductivity type first semiconductor layer; a first conductivity-type second semiconductor layer disposed on the light absorption layer; an amplification layer disposed on the first conductivity-type second semiconductor layer; and a second conductivity-type semiconductor layer disposed on the amplification layer, wherein the buffer layer includes a first layer including AlGaN, wherein the first layer includes a first surface disposed closest to the substrate and the and a second surface disposed closest to the filter layer, wherein the first surface has an Al composition greater than that of the second surface.

According to the embodiment, the embodiment may implement a semiconductor device having improved responsiveness and transmittance.

Various and advantageous advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention.

1 is a view showing a sensor according to an embodiment,
2 is a view showing the intensity of each wavelength for the excitation light of the light emitting device and the fluorescence of mold in FIG. 1;
3 is a conceptual diagram illustrating an electronic product according to an embodiment;
4 is a cross-sectional view of a semiconductor device according to an embodiment;
5 is a diagram illustrating an electric field distribution of a semiconductor device according to an embodiment;
6A is a view showing a buffer layer and a first conductivity-type first semiconductor layer of a semiconductor device according to an embodiment;
6B is a cross-sectional view of a buffer layer according to an embodiment;
6C is a cross-sectional view of a buffer layer according to another embodiment;
7 is a graph showing the transmittance of the buffer layer according to the embodiment,
8 is a graph showing the response of the buffer layer according to the embodiment,
9a to 9c are diagrams showing the electric field distribution (Electric Field) according to the Al composition of the amplification layer,
10 is a view for explaining a light absorption layer of a semiconductor device according to an embodiment;
11B is a view for explaining a difference in band gap energy of a light absorption layer according to an embodiment;
12A to 12B are diagrams for explaining an effect of an electric field distribution of a light absorption layer according to an embodiment.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated and described in the drawings. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms including an ordinal number such as second, first, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as the first component, and similarly, the first component may also be referred to as the second component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that no other element is present in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, the embodiment will be described in detail with reference to the accompanying drawings, but regardless of the reference numerals, the same or corresponding components are given the same reference numerals, and the overlapping description thereof will be omitted.

The semiconductor device according to the present embodiment may be a light receiving device.

The light receiving element may include a thermal element that converts photon energy into thermal energy, or a photoelectric element that converts photon energy into electrical energy. In particular, the photoelectric device may generate electrons and holes by absorbing light energy greater than or equal to the energy band gap of the light absorbing layer material in the light absorbing layer. In addition, current may be generated by the movement of electrons and holes by an electric field applied from the outside of the photoelectric device.

The semiconductor device according to the present embodiment may be an Avalanche PhotoDiode (APD). The APD may further include an amplification layer having a high electric field between the first and second conductivity-type semiconductor layers. Electrons or holes moved to the amplification layer collide with atoms around them by a high electric field to create new electrons and holes, and the current can be amplified by repeating this process. Accordingly, the APD can respond sensitively to even a small amount of light, and thus can be used as a high-sensitivity sensor or long-distance communication.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them.

1 is a diagram illustrating a sensor according to an embodiment.

Referring to FIG. 1 , the detection sensor according to the embodiment includes a housing 3000 , a light emitting device 2000 disposed on the housing 3000 , and a semiconductor device 1000 disposed on the housing 3000 . Here, the semiconductor device 1000 may be a semiconductor device according to the above-described embodiment.

The housing 3000 may include a circuit pattern (not shown) electrically connected to the ultraviolet light emitting device 2000 and the semiconductor device 1000 . The housing 3000 is not particularly limited as long as it is configured to electrically connect an external power source and an element.

The housing 3000 may include a control module (not shown) and/or a communication module (not shown). Accordingly, the size of the sensor can be reduced. The control module may apply power to the ultraviolet light emitting device 2000 and the semiconductor device 1000 , amplify a signal detected by the semiconductor device 1000 , or transmit the detected signal to the outside. The control module may be an FPGA or an ASIC. The present invention is not limited thereto.

The light emitting device 2000 may output light in an ultraviolet wavelength band to the outside of the housing 3000 . The light emitting device 2000 may output light (UV-A) in the near-ultraviolet wavelength band, may output light (UV-B) in the far-ultraviolet wavelength band, and emit light (UV-C) in the deep-ultraviolet wavelength band. can do. The ultraviolet wavelength band may be determined by the Al composition ratio of the light emitting device 1000 . Illustratively, the light (UV-A) in the near-ultraviolet wavelength band may have a wavelength in the range of 320 nm to 420 nm, and the light (UV-B) in the far-ultraviolet wavelength band may have a wavelength in the range of 280 nm to 320 nm, deep ultraviolet rays Light in the wavelength band (UV-C) may have a wavelength in a range of 100 nm to 280 nm.

Various microorganisms can be present in the outside air. The microorganism (P) may be a biological particle including mold, bacteria, bacteria, and the like. That is, it can be distinguished from non-living particles such as dust. When the microorganism (P) absorbs strong energy, a characteristic fluorescence is generated.

For example, the microorganism P may absorb light of a predetermined wavelength band and emit a fluorescence spectrum of a predetermined wavelength band. That is, the microorganism (P) consumes a portion of the absorbed light and emits a fluorescence spectrum in a certain wavelength band.

Accordingly, the semiconductor device 1000 detects the fluorescence spectrum emitted by the microorganism P. Since each microorganism (P) emits a different fluorescence spectrum, the existence and type of the microorganism (P) can be known by examining the fluorescence spectrum emitted by the microorganism (P).

The light emitting device 2000 may be a UV light emitting diode, and the semiconductor device 1000 may be a semiconductor device according to the above-described embodiment and may be a UV photodiode.

FIG. 2 is a view showing the intensity of each wavelength of the excitation light of the light emitting device and the fluorescence of mold in FIG. 1 .

Referring to FIG. 2 , the light applied to the semiconductor device that is the light receiving device in FIG. 1 may include excitation light generated from the light emitting device and fluorescence generated by mold or the like by the excitation light. In addition, as described below, the excitation light may have high response intensity at wavelengths of 280 nm and 325 nm.

Accordingly, in the semiconductor device in the sensor according to the embodiment, the Al composition ratio and thickness may be controlled so that the filter layer allows light of 320 nm or more to pass through as much as possible. In addition, in the semiconductor device according to the embodiment, the first conductivity type second semiconductor layer so that the electric field strength does not change in the amplification layer and the light absorption layer even when the thickness of the light absorption layer changes (so that the electric field strength of the amplification layer is higher than the electric field strength of the light absorption layer) The thickness and Si doping concentration can be set. With this configuration, the semiconductor device may provide an improved gain by absorbing a plurality of light in the light absorption layer, and improve accuracy in sensing only light of a desired wavelength band.

3 is a conceptual diagram of an electronic product according to an embodiment.

Referring to FIG. 3 , the electronic product according to the embodiment includes a case 2 , a detection sensor 10 disposed in the case 2 , a functional unit 40 performing a function of the product, and a control unit 20 . do.

The electronic product may be a concept including various home appliances and the like. For example, the electronic product may be a home appliance that performs a predetermined role by receiving power, such as a refrigerator, an air purifier, an air conditioner, a water purifier, and a humidifier.

However, the present invention is not necessarily limited thereto, and the electronic product may include a product having a predetermined sealed space, such as an automobile. That is, the electronic product may be a concept including all of the various products that need to confirm the existence of the microorganism 1 .

The function unit 40 may perform a main function of the electronic product. For example, when the electronic component is an air conditioner, the functional unit 40 may be a part that controls the temperature of the air. Also, when the electronic component is a water purifier, the functional unit 40 may be a water purifier.

The control unit 20 may communicate with the function unit 40 and the detection sensor 10 . The controller 20 may operate the detection sensor 10 to detect the presence and type of microorganisms introduced into the case 2 . As described above, since the detection sensor 10 according to the embodiment can be miniaturized in a module form, it can be mounted on electronic products of various sizes.

The control unit 20 may detect the concentration and type of microorganisms by comparing the signal detected by the detection sensor 10 with data stored in advance. The pre-stored data may be stored in the memory in the form of a look-up table, and may be periodically updated.

As a result of the detection, when the concentration of microorganisms is greater than or equal to a preset reference value, the control unit 20 may drive the washing system or output a warning signal to the display unit 30 .

4 is a cross-sectional view of a semiconductor device according to an embodiment, and FIG. 5 is a diagram illustrating an electric field distribution of the semiconductor device according to the embodiment.

Referring to FIG. 4 , the semiconductor device 100 according to the embodiment may include a substrate 110 , a semiconductor structure 120 , a first electrode 131 , and a second electrode 132 . In addition, a buffer layer 115 may be further disposed between the substrate 110 and the semiconductor structure 120 .

First, the substrate 110 may be a light-transmitting, conductive, or insulating substrate 110 . For example, the substrate 110 may include at least one _{of sapphire (Al 2} O ₃ ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga ₂ O _{3 .}

The substrate 110 may have a thickness T ₁ of 2400 nm to 3600 nm. Here, the thickness means a length in the stacking direction of the semiconductor device 100 . However, it is not limited to this length.

The buffer layer 115 may be disposed on the substrate 110 . The buffer layer 115 may relieve deformation caused by a difference in lattice constant between the substrate 110 and the first conductivity-type first semiconductor layer 122 .

In addition, the buffer layer 115 may prevent diffusion of a material included in the substrate 110 . To this end, the buffer layer 115 may have a thickness of 300 to 3000 nm, but the present invention is not limited thereto. Here, the thickness is the thickness direction of the semiconductor structure 120 , and is the first direction.

The buffer layer 115 may include one selected from AlN, AlAs, GaN, AlGaN, and SiC, or a double layer structure thereof. The buffer layer 115 may be omitted in some cases.

_{The thickness T 2} of the buffer layer 115 may be 640 nm to 960 nm, but is not limited thereto. The configuration of the buffer layer 115 will be described in detail below with reference to FIGS. 6A to 6C .

The semiconductor structure 120 may be disposed on the substrate 110 (or the buffer layer 115 ). The semiconductor structure 120 of the semiconductor device 100 according to the embodiment includes a filter layer 121 , a first conductivity type first semiconductor layer 122 , a light absorption layer 123 , and a first conductivity type second semiconductor layer 124 . , an amplification layer 125 and a second conductivity type semiconductor layer 126 .

Each of the layers of the semiconductor structure 120 (the first conductivity type first semiconductor layer 122 , the barrier layer, the light absorption layer 123 , the first conductivity type second semiconductor layer 124 , the amplification layer 125 , and the second conductivity type) The type semiconductor layer 126) may be implemented with at least one of group III-V and group II-VI compound semiconductors. The semiconductor structure 120 may be formed of, for example, a semiconductor material having a compositional formula of _{In x} Al _y Ga _{1 -x- y N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).} . For example, the semiconductor structure 120 may include GaN.

The filter layer 121 may be disposed on the lowermost portion of the semiconductor structure 120 . The filter layer 121 may be an undoped, undoped layer.

The filter layer 121 may pass light having a wavelength less than or equal to a predetermined wavelength among light received through the substrate 110 and the buffer layer 115 and may filter light having a wavelength greater than a predetermined wavelength. The filter layer 121 may filter UV-C light having a central wavelength of 280 nm. For example, the filter layer 121 may filter light in a wavelength band of a predetermined ratio with respect to the central wavelength of UV-C light. With this configuration, the filter layer 121 may filter UV-C light irradiated to the mold or the like and pass light in the wavelength band of fluorescence generated from the mold. The filter layer 121 may filter light of a predetermined wavelength band, including Al. That is, the Al composition of the filter layer 121 may vary according to the wavelength band of the absorbed light. For example, the filter layer 121 of the semiconductor device 100 according to the embodiment has an Al composition of 15% and can absorb light of 320 nm or less. With this configuration, light having a wavelength greater than 320 nm may pass through the filter layer 121 .

Accordingly, the filter layer 121 may have a band gap to filter light having a wavelength smaller than a desired wavelength so that light having a wavelength smaller than a desired wavelength is not absorbed by the light absorption layer 123 .

However, the filter layer 121 does not filter light by being limited to this wavelength, and may have a wavelength band that is variably filtered according to the wavelength of the light absorbed by the light absorption layer 123 . For example, the thickness and composition of the filter layer 121 may be adjusted according to the absorption wavelength of the light absorption layer 123 . In this case, the filter layer 121 may pass light of a wavelength band greater than that of the light absorption layer 123 .

In addition, the filter layer 121 may have a band gap energy greater than or equal to a predetermined value in order to pass light having a wavelength greater than or equal to a desired wavelength. Accordingly, in the filter layer 121 , carrier recombination may occur due to a deep level within the band gap energy, and light may be generated by carrier recombination. In addition, the thickness (T ₃ ) of the filter layer 121 may be 400 nm to 600 nm, but is not limited thereto.

The first conductivity type first semiconductor layer 122 may be disposed on the substrate 110 (or the buffer layer 115 ). The first conductivity type first semiconductor layer 122 may be doped with a first dopant. Here, the first dopant may be an n-type dopant such as Si, Ge, Sn, Se, or Te. That is, the first conductivity-type first semiconductor layer 122 may be an n-type semiconductor layer doped with an n-type dopant. The first conductivity type first semiconductor layer 122 may have a thickness of 500 nm to 1500 nm, but the present invention is not limited thereto.

The first conductivity-type first semiconductor layer 122 may be a low-resistance layer and may be a contact layer in contact with an electrode. In addition, the first conductivity type first semiconductor layer 122 may perform secondary filtering. Illustratively, the first conductivity type first semiconductor layer 122 absorbs light of 320 nm or less that is not filtered by the filter layer 121 and passes light having a wavelength greater than 320 nm through the light absorption layer 123 to the filter layer 121 . It can complement the filter function of

In addition, a layer (hereinafter, a barrier layer) having a reduced Al composition may be disposed on the first conductivity type first semiconductor layer 122 . In the blocking layer, an energy band gap may be gently decreased in a direction from the first conductivity type first semiconductor layer 122 toward the light absorption layer 123 . The energy bandgap of the barrier layer in a region adjacent to the first conductivity-type first semiconductor layer 122 may be the same as that of the first conductivity-type first semiconductor layer 122 . Also, the energy band gap of the blocking layer in a region adjacent to the light absorption layer 123 may be the same as that of the light absorption layer 123 . With this configuration, an electric field is not formed from the light absorption layer 123 to the first conductivity type first semiconductor layer 122, and the electric field is concentrated in the amplification layer 125 to improve the current amplification phenomenon. have.

That is, in the blocking layer, the Al composition decreases from the first conductivity type first semiconductor layer 122 toward the light absorption layer 123 , so that the lattice imbalance between the first conductivity type first semiconductor layer 122 and the light absorption layer 123 . It is possible to remove the strain according to the In addition, the prevention layer is a negative electric field (kink) due to the distortion of the potential difference (kink) generated by the energy bandgap difference between the first conductivity type first semiconductor layer 122 and the light absorption layer 123 and the potential difference (kink). Electric Field) can be eliminated. Accordingly, in the blocking layer, an electric field toward the second conductivity type semiconductor layer 126 is concentrated in the amplification layer 125 , thereby improving carrier multiplication and current amplification.

_{Also, the thickness T 4} of the first conductivity-type first semiconductor layer 122 may be 800 nm to 1200 nm. However, it is not limited to this length.

The light absorption layer 123 may be disposed on the first conductivity-type first semiconductor layer 122 (or the prevention layer). The light absorption layer 123 may have a thickness of 100 nm to 200 nm, but the present invention is not limited thereto.

The light absorption layer 123 may be an i-type semiconductor layer. That is, the light absorption layer 123 may include an intrinsic semiconductor layer. Here, the intrinsic semiconductor layer may be an undoped semiconductor layer or an unintentionally doped semiconductor layer.

The unintentionally doped semiconductor layer may mean that N-vacancy occurs without doping with a dopant, for example, an n-type dopant such as a silicon (Si) atom, in a semiconductor layer growth process. At this time, if the N-vacancy increases, the concentration of excess electrons increases, so that even if it is not intended in the manufacturing process, electrical properties similar to those doped with the n-type dopant may be obtained. Up to a partial region of the light absorption layer 123 may be doped with a dopant by diffusion.

The light absorption layer 123 may absorb light incident on the semiconductor device 100 . That is, the light absorption layer 123 may absorb light having an energy greater than or equal to the energy band gap of the material forming the light absorption layer 123 to generate carriers including electrons and holes. In the semiconductor device 100 , current may flow due to the movement of carriers.

Also, the light absorption layer 123 may affect the gain of the semiconductor device 100 according to its thickness. For example, in the light absorption layer 123 , when the thickness of the light absorption layer 123 is increased, the strength of the electric field formed in the light absorption layer 123 is lowered. can get

In addition, the light absorption layer 123 may have a relatively lower electric field strength than the amplification layer 125 . In addition, the light absorption layer 123 may have different materials depending on the wavelength of the characteristic fluorescence generated by microorganisms such as mold.

In addition, the thickness T ₅ of the light absorption layer 123 may be 150 nm to 400 nm. However, it may have various lengths as described below and is not limited thereto.

The first conductivity-type second semiconductor layer 124 may be disposed on the light absorption layer 123 . The first dopant mentioned above may be doped in the first conductivity-type second semiconductor layer 124 . That is, the first conductivity-type second semiconductor layer 124 may be an n-type semiconductor layer doped with an n-type dopant.

The first conductivity-type second semiconductor layer 124 may be disposed between the light absorption layer 123 and the amplification layer 125 . The first conductivity type second semiconductor layer 124 may have a different electric field between the light absorption layer 123 and the amplification layer 125 by adjusting the thickness and Si doping concentration. In particular, the first conductivity-type second semiconductor layer 124 may allow a higher electric field to be concentrated in the amplification layer 125 as shown in FIG. 2 . Accordingly, the multiplication action of carriers may be concentrated in the amplification layer 125 having the highest electric field.

The first conductivity-type second semiconductor layer 124 may have a thickness T ₆ of 20 nm to 60 nm. In addition, the first conductivity-type second semiconductor layer 124 may have a Si doping of 2E18/cm ³ to 3E18/cm ³ . This will be described below.

Referring to FIG. 2 , in the first conductivity type second semiconductor layer 124 , the first slope of the electric field strength increases between the first conductivity type first semiconductor layer 122 and the light absorption layer 123 according to the Si doping concentration. (S1), the maximum electric field strength M1 in the first conductivity type first semiconductor layer 122, the second slope S2 of the increasing electric field strength in the first conductivity type second semiconductor layer 124, and the amplification layer ( 125) to change the maximum electric field strength (M2). (Distance in FIG. 2 is the direction of the first conductivity type first semiconductor layer 122 from the lower first conductivity type first semiconductor layer 122 to the upper second conductivity type semiconductor layer 126 . Shows the electric field measured from a partial area.

The first conductivity type second semiconductor layer 124 decreases the maximum electric field strength in the light absorption layer 123 when the Si doping concentration in the first conductivity type second semiconductor layer 124 increases, and the maximum electric field strength in the amplification layer 125 is increased. The electric field strength M2 may be increased.

When the Si doping concentration increases, the first conductivity-type second semiconductor layer 124 has an electric field strength that increases between the first conductivity-type first semiconductor layer 122 and the light absorption layer 123 due to a decrease in potential difference due to an energy bandgap. The first slope S1 may decrease, and the maximum electric field strength M1 in the first conductivity type first semiconductor layer 122 may decrease. In addition, in the first conductivity type second semiconductor layer 124 , when the Si doping concentration increases, the second slope S2 of the electric field strength that increases in the first conductivity type second semiconductor layer 124 increases, and the amplification layer ( 125), the maximum electric field strength M2 may increase. With this configuration, the first conductivity-type second semiconductor layer 124 may control the electric field applied to the light absorption layer 123 and the amplification layer 125 to improve the gain and responsiveness of the semiconductor device. However, the electric field may vary depending on the composition ratio of factors such as thickness and Al as well as Si concentration.

Referring back to FIG. 1 , the amplification layer 125 may be disposed on the first conductivity-type second semiconductor layer 124 . The amplification layer 125 may be an i-type semiconductor layer like the light absorption layer 123 . In addition, the amplification layer 125 may further include Al. That is, the amplification layer 125 may be composed of a compound of Al and the material included in the light absorption layer 123 . For example, the amplification layer 125 may have a single-layer structure including AlGaN.

In addition, the amplification layer 260 has _{the composition formula of In x} Al _y Ga _{1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) as in the above-mentioned embodiment. It can be formed of a semiconductor material having

The amplification layer 125 may multiply carriers generated in the light absorption layer 123 . That is, the amplification layer 125 may have an avalanche function. Avalanche refers to a phenomenon in which the semiconductor device 100 to which the reverse bias is applied absorbs light to generate carriers, and by these, other carriers are continuously generated to amplify the current.

Carriers moved to the amplification layer 125 collide with surrounding atoms to generate new electron and hole carriers, which collide with surrounding atoms to generate carriers, thereby multiplying the carriers. In the amplification layer 125 , an electric field is applied the highest, so that the multiplication action of carriers can be concentrated. In addition, the current of the semiconductor device 100 may be increased by the multiplication of carriers. That is, the semiconductor device 100 can amplify a current by amplifying carriers even when light having a low energy is incident by the amplification layer 125 . In other words, it is possible to detect low energy light, so that light reception sensitivity can be improved.

Meanwhile, since the amplification layer 125 further includes Al, the amplification effect may be further improved. That is, the electric field in the amplification layer 125 may be increased by Al included in the amplification layer 125 . Specifically, the Al composition will be described in detail with reference to FIGS. 9A to 9C below.

_{The thickness T 7} of the amplification layer 125 may be 50 nm to 200 nm.

The second conductivity type semiconductor layer 126 may be disposed on the amplification layer 125 . The second conductivity type semiconductor layer 126 may be doped with a second dopant. Here, the second dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. That is, the second conductivity-type semiconductor layer 126 may be a p-type semiconductor layer doped with a p-type dopant. The second conductivity type semiconductor layer 126 may have a thickness of 300 nm to 400 nm, but the present invention is not limited thereto.

_{The thickness T 8} of the second conductivity type semiconductor layer 126 may be 280 nm to 420 nm, but is not limited thereto.

The semiconductor structure 120 according to the embodiment of the present invention may have a structure in which a nin diode and a nip diode are bonded to each other by the first conductive type second semiconductor layer 124 . That is, the first conductivity type first semiconductor layer 122 (n-type semiconductor layer), the light absorption layer 123 (i-type semiconductor layer), and the first conductivity type second semiconductor layer 124 (n-type semiconductor layer) are nin structure, a first conductivity type second semiconductor layer 124 (n-type semiconductor layer), an amplification layer 125 (i-type semiconductor layer), a second conductivity type semiconductor layer 126 (p-type semiconductor layer) You can achieve this nip structure.

In general, the i-type semiconductor layer can form a high electric field by having a higher resistance value than that of the n-type semiconductor layer and the p-type semiconductor layer. In addition, the p-type semiconductor layer among the n-type semiconductor layer and the p-type semiconductor layer has a higher resistance value, so that a higher electric field can be formed. Therefore, it may be advantageous to amplify carriers in a region adjacent to the p-type semiconductor layer that forms a higher electric field.

For example, by disposing the first conductivity-type second semiconductor layer 124 between the light absorption layer 123 and the amplification layer 125 , a higher electric field may be concentrated in the amplification layer 125 .

In addition, since the amplification layer 125 further includes Al, the electric field of the amplification layer 125 may be higher. Accordingly, acceleration and multiplication of carriers may be intensively performed in the amplification layer 125 by the high electric field concentrated in the amplification layer 125 .

The first electrode 131 may be disposed on the first conductivity-type first semiconductor layer 122 . The first electrode 131 may be electrically connected to the first conductivity-type first semiconductor layer 122 . The first electrode 131 may be selected from Ti, Ru, Rh, Ir, Mg, Zn, Al, In, Ta, Pd, Co, Ni, Si, Ge, Ag, Au, and optional alloys thereof.

The second electrode 132 may be disposed on the second conductivity-type semiconductor layer 126 . The second electrode 132 may be electrically connected to the second conductivity-type semiconductor layer 126 . The second electrode 132 may be formed of the same material as the first electrode 131 .

6A is a view illustrating a buffer layer and a filter layer of a semiconductor device according to an embodiment, FIG. 6B is a cross-sectional view of the buffer layer according to the embodiment, and FIG. 6C is a cross-sectional view of a buffer layer according to another embodiment.

6A , the buffer layer 1150 of the semiconductor device according to the embodiment may include a plurality of layers. The buffer layer includes a first buffer layer 115-1, a second buffer layer 115-2, and a third buffer layer ( 115-3) may be included.

The first buffer layer 115 - 1 may be disposed on the lowermost portion of the buffer layer. The first buffer layer 115 - 1 may be disposed on the substrate. Accordingly, the first buffer layer 115 - 1 may contact the buffer layer.

As described above, the buffer layer 115 may include one selected from AlN, AlAs, GaN, AlGaN, and SiC, or a double layer structure thereof. The buffer layer 115 may be omitted in some cases. Here, the first buffer layer 115 - 1 may include AlN.

The second buffer layer 115 - 2 may be disposed on the first buffer layer 115 - 1 . The second buffer layer 115 - 2 may include Al _x Ga _{1 - x} N. (where x represents a composition (%) of Al in each layer) The second buffer layer 115 - 2 may be disposed between the third buffer layer 115 - 3 and the first buffer layer 115 - 1 .

The second buffer layer 115 - 2 may include a first surface S1 disposed closest to the substrate side. The first surface S1 may be disposed on the lowermost portion of the second buffer layer 115 - 2 . The first surface S1 may be a surface in which the second buffer layer and the first buffer layer 115 - 1 contact each other.

The third buffer layer 115 - 3 may be disposed on the second buffer layer 115 - 2 . The third buffer layer 115 - 3 may be disposed under the filter layer 121 . The third buffer layer 115 - 3 may be disposed between the second buffer layer 115 - 2 and the filter layer 121 . The third buffer layer 115 - 3 may include a second surface S2 disposed closest to the filter layer 121 . The second surface S2 may be disposed on the top of the third buffer layer 115 - 3 . The second surface S2 may be a surface in which the third buffer layer 115 - 3 and the filter layer 121 disposed on the third buffer layer 115 - 3 contact each other.

And the third buffer layer 115 - 3 may include Al _x Ga _{1 - x} N. (Here, x represents a composition (%) of Al in each layer) However, the third buffer layer 115 - 3 may have a different Al composition from the second buffer layer 115 - 2 .

The Al composition of the second buffer layer 115 - 2 may be greater than the Al composition of the third buffer layer 115 - 3 . That is, the Al composition of the first surface S1 may be greater than that of the second surface S2 . Al composition of the second buffer layer 115 - 2 and the second third buffer layer 115 - 3 may decrease from the substrate toward the filter layer 121 .

As shown in FIG. 6B , the Al composition of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may be gradually decreased from the substrate toward the filter layer 121 . For example, the Al composition of the second buffer layer 115 - 2 may be A. Also, the third buffer layer 115 - 3 may have an Al composition of B. And A can be greater than B. Accordingly, the band gap energy of the second buffer layer 115 - 2 may be greater than the band gap energy of the third buffer layer 115 - 3 . Also, the Al composition of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may be greater than that of the filter layer 121 . Due to this configuration, the second buffer layer 115 - 2 and the third buffer layer 115 - 3 have an energy bandgap greater than that of the filter layer 121 , so that light transmitted from the filter layer 121 can pass through the buffer layer 115 . have. For example, when the Al composition of the filter layer 121 is 20% and it is designed to transmit light of 320 nm or more, the Al composition of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may be greater than 20%. Accordingly, the filter layer 121 may transmit light incident on the semiconductor device with sharper transmittance at a desired wavelength. For example, the filter layer 121 may transmit light having a wavelength greater than 320 nm and absorb light having a wavelength smaller than 320 nm. Here, the boundary wavelength between the absorbed light and the transmitted light is referred to as a cut wavelength. In the above example, the cutoff wavelength may be 320 nm.

In addition, the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may be sharply formed at a wavelength at which light transmitted through the filter layer 121 is blocked. That is, the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may increase the difference in transmittance of light between 320 nm and 320 nm or more based on a desired wavelength (blocking wavelength).

In addition, the Al composition of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may decrease linearly from the substrate toward the filter layer 121 as shown in FIG. 6C . For example, the Al composition may be A on the first surface S1, which is the lowermost portion of the second buffer layer 115 - 2 . Also, the Al composition may be B on the second surface S2, which is the uppermost portion of the third buffer layer 115 - 3 . In addition, the Al composition may linearly decrease from the first surface S1 to the second surface S2 . And A can be greater than B. Accordingly, the band gap energy of the second buffer layer 115 - 2 may be greater than the band gap energy of the third buffer layer 115 - 3 . Also, the Al composition of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may be greater than that of the filter layer 121 . Due to this configuration, the second buffer layer 115 - 2 and the third buffer layer 115 - 3 have an energy bandgap greater than that of the filter layer 121 , so that light transmitted from the filter layer 121 can pass through the buffer layer 115 . have. For example, when the Al composition of the filter layer 121 is 20% and it is designed to transmit light of 320 nm or more, the Al composition of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may be greater than 20%. Accordingly, the filter layer 121 may transmit light incident on the semiconductor device with sharper transmittance at a desired wavelength. As described above, the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may facilitate coupling with the filter layer 121 disposed thereon. Due to this, the number of defects in the filter layer may be reduced, and thus the light filtering effect at the cutoff wavelength may be improved. For example, the filter layer 121 may transmit light having a wavelength greater than 320 nm and absorb light having a wavelength smaller than 320 nm.

In addition, the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may have a total thickness of 400 nm to 1000 nm. When the total thickness of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 is less than 400 nm, the thickness of the buffer layer becomes thin, and thus a surface morphology occurs. In addition, when the total thickness of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 is greater than 1000 nm, there is a limitation in that a warpage phenomenon of the wafer (eg, a wafer bow) occurs.

Each of the second buffer layer 115 - 2 and the third buffer layer 115 - 3 may have the same thickness. However, the present invention is not limited thereto.

7 is a graph showing the transmittance of the buffer layer according to the embodiment, and FIG. 8 is a graph showing the response of the buffer layer according to the embodiment.

Referring to FIG. 7 , in FIG. 7 , a represents light transmittance (%) according to wavelength when the second buffer layer and the third buffer layer are present in the semiconductor device, and b represents the second buffer layer and the third buffer layer in the semiconductor device. When only the first buffer layer is present without the light transmittance (%).

Specifically, the semiconductor structure may be configured based on GaN. Here, the amplification layer may further include Al and include AlGaN. a to b have a difference only in the structure of the buffer layer, and the rest may be configured the same.

The first conductivity type first semiconductor layer may be n-GaN, and may have a thickness of 200 nm and a doping concentration of 5E18/cm 3 . The light absorption layer may be i-GaN, and may have a thickness of 100 nm and a doping concentration of 1E16/cm 3 . The first conductivity-type second semiconductor layer may be n-GaN, and may have a thickness of 40 nm and a doping concentration of 1E18/cm3. The amplification layer may have a doping concentration of 1E16/cm3. The second conductivity type semiconductor layer may be p-GaN, and may have a thickness of 300 nm and a doping concentration of 1.5E17/cm 3 . However, this is only an example for constructing the following experimental examples, and the present invention is not limited thereto.

At this time, when the second buffer layer and the third buffer layer are present as shown in FIG. 7 , absorption and transmission of light can be clearly distinguished based on 320 nm. That is, the sharpness of the transmittance according to the wavelength of the semiconductor device may increase based on the cutoff wavelength of 320 nm. That is, the filter layer of the semiconductor device is an optical filter, and selectivity with respect to a wavelength may be improved.

Referring to FIG. 8 , the above cases may be equally applied to a and b. That is, the semiconductor device according to the embodiment may have improved responsiveness. Here, the response (responsivity) represents the current output when 1W of light is applied to the semiconductor device. That is, it can be said that the performance of the semiconductor device as a photodetector is improved when the response is high in a desired wavelength band.

Since the sharpness of absorption/transmission is improved at the cutoff wavelength, the semiconductor device according to the embodiment can also clearly provide response at the cutoff wavelength (320 nm in FIG. 8 ). Specifically, the semiconductor device does not show a large difference in response at a wavelength of 360 nm depending on the presence or absence of the second buffer layer and the third buffer layer. However, the semiconductor device exhibits a difference in responsiveness in a band adjacent to the cutoff wavelength in case a in which the second and third buffer layers are present than in case b in which the buffer layer is not present. That is, the semiconductor device according to the embodiment may provide improved response in a wavelength region adjacent to the cutoff wavelength.

9A to 9C are diagrams illustrating an electric field distribution according to an Al composition of an amplification layer;

9A to 9C , the amplification layer of the semiconductor device according to the embodiment may include Al. The amplification layer may have an Al composition of 1% to 20%. In FIG. 9A , the amplification layer may be made of GaN without including Al. In addition, in FIG. 9B, the Al composition of the amplification layer may be 10%, and in FIG. 9C, the Al composition may be 20%.

The amplification layer 125 may have the highest electric field as described above. Accordingly, the high electric field of the amplification layer 125 is advantageous for the acceleration of carriers, and the amplification of carriers and currents can be made more effectively.

And the thickness of the amplification layer 125 may be 50 nm to 200 nm. When the thickness of the amplification layer 125 is less than 50 nm, the space in which the amplification of carriers can be made becomes smaller, so that the improvement in the amplification effect may be insignificant. When the thickness of the amplification layer 125 is greater than 200 nm, the electric field becomes small and a negative (-) electric field may be formed.

As shown in FIGS. 9A to 9C , it can be seen that a high electric field is concentrated in a region of 420 nm to 590 nm in which the amplification layer is disposed. That is, a higher electric field may be formed in the amplification layer than in the light absorption layer by the second semiconductor layer of the first conductivity type. Carriers generated in the light absorption layer may be accelerated by the high electric field of the amplification layer to improve current amplification efficiency.

In FIG. 9A , the maximum electric field value may be approximately 1.41 MV/cm. However, it can be seen from FIGS. 9A to 9C that the maximum electric field value gradually increases as the Al composition gradually increases. That is, the amplification layer of the present invention may include Al to increase the electric field value. In addition, the current amplification effect may be further improved due to the acceleration of the carriers by the higher electric field.

Meanwhile, in the case of FIG. 9C , it can be seen that the electric field has a negative value in the 400 nm region (the region between the light absorption layer and the first conductivity-type second semiconductor layer). That is, in the case of FIG. 9C , the Al composition may be increased to have a higher electric field, but carriers may not move due to the generation of a barrier according to the negative electric field. Therefore, it may be preferable that the Al composition of the amplification layer be set to 20% or less.

In addition, when the amplification layer does not contain Al, the synergistic effect of the electric field according to the present invention cannot be obtained. That is, as in FIG. 9A , when the amplification layer does not include Al, the amplification effect of the current may be insignificant. According to the above results, it can be seen that the Al composition according to the present invention is preferably formed to be greater than 0% and less than 20%.

In addition, the amplification layer according to the embodiment may include AlGaN and have a higher band gap energy than the amplification layer including only GaN. With this configuration, the amplification layer of the semiconductor device according to the embodiment has a large energy band gap, so that the level of dark current can be reduced. In addition, since the amplification layer has conductivity by doping with Si, there is a problem in that carriers move from the light absorption layer through the first conductivity type second semiconductor layer to the amplification layer, and loss occurs due to scattering of carriers. do. In this case, the amplification layer according to the embodiment reduces the Si doping concentration to reduce resistance, and thus, scattering of carriers can be prevented.

10 is a diagram illustrating a light absorption layer of a semiconductor device according to an embodiment, FIGS. 11A to 11B are diagrams illustrating a difference in band gap energy of a light absorption layer according to an embodiment, and FIGS. 12A to 12B are diagrams for an embodiment It is a diagram for explaining the effect of the electric field distribution of the light absorption layer.

Referring to FIG. 10 , the light absorption layer 123 of the semiconductor device of the semiconductor device according to the embodiment may be formed of a plurality of layers. For example, the light absorption layer 123 may include a first light absorption layer 123-1 and a second light absorption layer 123-2. The first light absorption layer 123 - 1 may be disposed under the light absorption layer 123 . The first light absorption layer 123 - 1 may be in contact with the first conductivity type first semiconductor layer. Also, the second light absorption layer 123 - 2 may be disposed on the first light absorption layer 123 - 1 . In addition, the second light absorption layer 123 - 2 may have a first conductivity-type second semiconductor layer disposed thereon.

The first light absorption layer 123 - 1 may include AlGaN or InGaN. According to this configuration, in growing the second light absorption layer 123-2 disposed thereon on the first conductivity type first semiconductor layer, mismatch defects occurring in heterogeneous growth, surface morphology ( Structural limitations such as surface morphology can be avoided.

A second light absorbing layer 123-2 is In _y Ga _{1 -} may include N _y. The second light absorption layer 123 - 2 may have an In composition of 2% to 5%. With this configuration, the energy band gap of the second light absorption layer 123 - 2 may be lower than that of the case of including AlGaN.

11A to 11B, FIG. 11A is a view showing the band gap energy when the light absorption layer contains only AlGaN, and FIG. 11B is a light absorption layer comprising a first light absorption layer and a second light absorption layer as in the embodiment. It is a diagram showing the band gap energy in the case of being made.

11A to 11B , the light absorption layer may be positioned at 200 nm to 400 nm in the semiconductor device. In this case, the first light absorption layer and the second light absorption layer may include In ( FIG. 11B ), and thus the band gap energy may be lower than that of the case where the light absorption layer includes only AlGaN ( FIG. 11A ). With this configuration, the light absorption layer according to the embodiment may improve the absorption efficiency of the light absorption layer through a smaller band gap energy. Also, as shown in FIGS. 12A to 12B , the light absorption layer according to the embodiment may have a small electric field distribution due to a small band gap energy. Here, FIG. 12A is a view showing the electric field distribution when the light absorption layer contains only AlGaN, and FIG. 12B is a view showing the electric field distribution when the light absorption layer consists of a first light absorption layer and a second light absorption layer as in the embodiment. It is a drawing.

In addition, the light absorption layer according to the embodiment may have a thickness of 130 nm to 200 nm. When the thickness of the light absorption layer is less than 130 nm, the current generated by absorbing light having an energy greater than or equal to the energy band gap of the material for forming the light absorption layer to generate carriers including electrons and holes has a weak limit. In addition, when the thickness of the light absorption layer is greater than 200 nm, the electric field distribution is reduced and diffusion to the generated photocarriers is reduced, thereby reducing the efficiency of the semiconductor device.

In the above, the embodiment has been mainly described, but this is only an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in the range that does not depart from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (10)

Board;
a buffer layer disposed on the substrate;
a filter layer disposed on the buffer layer;
a first conductivity-type first semiconductor layer disposed on the filter layer;
a light absorption layer disposed on the first conductivity type first semiconductor layer;
a first conductivity-type second semiconductor layer disposed on the light absorption layer;
an amplification layer disposed on the first conductivity-type second semiconductor layer; and
a second conductivity-type semiconductor layer disposed on the amplification layer;
The buffer layer comprises a first layer comprising AlGaN,
The first layer includes a first surface disposed closest to the substrate and a second surface disposed closest to the filter layer,
The first surface is a semiconductor device having an Al composition greater than that of the second surface.
According to claim 1,
The buffer layer is
A semiconductor device in which Al composition decreases linearly or stepwise from the first surface toward the second surface.
According to claim 1,
The first layer has a band gap energy greater than a band gap energy of the filter layer and a band gap energy of the light absorption layer,
The buffer layer includes a second layer between the first layer and the substrate, and the second layer includes AlN.
According to claim 1,
The Al composition of the first surface is 60%, the Al composition of the second surface is 20%,
The amplification layer includes AlGaN, and the Al composition is greater than 0% and less than 20%.
According to claim 1,
The light absorption layer is
a first light absorption layer including InGaN or AlGaN; and
a second light absorption layer disposed on the first light absorption layer;
The second light absorption layer,
A semiconductor device having an In composition of 2% to 5%. delete delete delete delete delete

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