LSPR-based single-photon detector and manufacturing method therefor

Abstract

Provided is a method of manufacturing a single photon detection device, the method including the steps of: forming a PN junction having a p-type region and a n-type region in a horizontal direction on a substrate; and forming a metal nanoprism structure on the PN junction, wherein the metal nanoprism structure induces LSPR at a wavelength of 900 nm to 1550 nm to increase light absorption of incident photons.

Description

LSPR-based single-photon detector and its manufacturing method

[0001] The present invention relates to a LSPR-based single-photon detector and a method for manufacturing the same, and more particularly, to a single-photon detector with improved light detection sensitivity and a method for manufacturing the same using a Si lateral pn junction diode having a metal nanostructure formed therein for inducing localized surface plasmon resonance (LSPR).

[0002] As autonomous driving technology advances, demand is increasing for sensor systems capable of precisely recognizing a vehicle's surroundings. In particular, to achieve Level 5 full autonomous driving, LiDAR sensors, capable of recognizing not only objects around the vehicle but also spatial information such as buildings and terrain with high precision, are essential. To ensure safety and reliability, these LiDAR sensors require highly sensitive photodetectors capable of detecting even the smallest signals at the single photon level.

[0003] In general, a Si CMOS-based single-photon avalanche diode (SPAD) is widely used as the light-receiving element of the LiDAR sensor, and this has a structure that uses a near-infrared (NIR) laser with a wavelength of 905 nm as a light source.

[0004] The 905 nm wavelength has the advantage of being relatively inexpensive and easy to miniaturize, but its use at high output is limited due to the risk of retinal damage, and as a result, a highly sensitive detection element that can operate stably even at very low light intensities is required.

[0005] Conventional SPADs are generally designed to enable sensitive detection of single photons by applying a high reverse bias voltage to a pn junction diode to induce impact ionization when charge generation by a single photon occurs in the depletion region, thereby generating an avalanche current.

[0006] However, the above structure has limited light absorption efficiency, and there are technical limitations in improving sensitivity, especially in a specific wavelength range (e.g., 905 nm).

[0007] Meanwhile, localized surface plasmon resonance (LSPR) is a phenomenon in which, when light of a specific wavelength is incident on a metal nanostructure, free electrons on the metal surface collectively oscillate due to resonance with the photons, inducing strong electric field enhancement. This LSPR phenomenon can dramatically increase the light absorption rate of a specific wavelength range around the metal nanostructure, and has recently been actively studied in various energy and optical sensor applications such as water splitting, carbon dioxide reduction, artificial photosynthesis, and photoelectric devices.

[0008] Accordingly, there is a technological need to improve the photosensitivity of single-photon detectors and their efficiency in specific wavelength ranges (e.g., 905 nm).

[0009]

[0010] The technical problem to be achieved by the present invention is to provide a single photon detector with improved light detection sensitivity and a method for manufacturing the same by using a Si lateral pn junction diode having a metal nanostructure formed to induce localized surface plasmon resonance (LSPR).

[0011]

[0012] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0013] In order to achieve the above technical task, one embodiment of the present invention provides a method for manufacturing a single photon detector.

[0014] The method for manufacturing the single photon detector according to one embodiment of the present invention,

[0015] A step of forming a PN junction having a horizontal p-type region and an n-type region on a substrate; and a step of forming a metal nanoprism structure on the PN junction;

[0016] The above metal nanoprism structure may be a method for manufacturing a single photon detector characterized in that it induces localized surface plasmon resonance (LSPR) at a wavelength of 900 nm to 1550 nm to increase light absorption of incident photons.

[0017]

[0018] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of forming the PN junction includes the step of forming a p-type region on an n-type silicon substrate; and the step of performing a heat treatment on the p-type region to activate doping.

[0019]

[0020] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of forming the p-type region is such that a plurality of p-type regions in the form of stripes spaced apart at predetermined intervals are repeatedly arranged on the n-type silicon substrate.

[0021] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the predetermined interval is 25 μm to 35 μm.

[0022]

[0023] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the p-type region in the stripe shape has a width of 5 μm to 15 μm.

[0024] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of forming the p-type region includes the step of defining a doped region by performing a photolithography process on an n-type silicon substrate; and the step of ion implanting a p-type dopant into the doped region.

[0025] In addition, according to one embodiment of the present invention, the step of ion-implanting the p-type dopant is such that the doping concentration of the p-type dopant is 10 15 cm -3 10 inland 19 cm -3 There may be a method for manufacturing a single photon detector characterized by having a range of .

[0026]

[0027] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of ion-implanting the p-type dopant is characterized in that the injection energy is 40 keV to 60 keV.

[0028]

[0029] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of activating the doping comprises performing heat treatment in a temperature range of 1000°C to 1100°C.

[0030]

[0031] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of forming the metal nanoprism structure includes the steps of: transferring a polystyrene bead onto the PN junction; depositing a metal entirely on the PN junction to which the polystyrene bead has been transferred; and removing the polystyrene bead to form a metal nanoprism pattern.

[0032]

[0033] In addition, according to one embodiment of the present invention, the step of depositing the metal comprises:

[0034] There may be a method for manufacturing a single photon detector, characterized by depositing a metal including at least one selected from the group consisting of silver (Ag), gold (Au), copper (Cu), ruthenium (Ru), and graphene quantum dots (GQDs).

[0035]

[0036] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of depositing the metal is performed through at least one deposition method selected from the group consisting of an evaporation method, a sputtering method, and an island formation method through heat treatment after thin film deposition.

[0037] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a single photon detector, characterized in that the step of transferring the polystyrene beads includes the step of dividing the PN junction into a plurality of regions; and the step of transferring polystyrene beads having different diameter sizes to each of the divided regions.

[0038]

[0039] In order to achieve the above technical task, another embodiment of the present invention provides a single photon detector.

[0040] According to one embodiment of the present invention, the single photon detector comprises:

[0041] A PN junction comprising a p-type region and an n-type region arranged horizontally on a substrate; and a metal nanoprism structure formed on the PN junction,

[0042] The above metal nanoprism structure may be a single photon detector characterized by inducing localized surface plasmon resonance (LSPR) at a wavelength of 900 nm to 1550 nm to increase light absorption of incident photons.

[0043]

[0044] In addition, according to one embodiment of the present invention, the PN junction,

[0045] There may be a single photon detector characterized by a structure in which a plurality of p-type regions in the form of stripes are repeatedly arranged at predetermined intervals on an n-type silicon substrate.

[0046] Additionally, according to one embodiment of the present invention, there may be a single photon detector characterized in that the predetermined interval is 25 μm to 35 μm.

[0047] Additionally, according to one embodiment of the present invention, there may be a single photon detector characterized in that the stripe-shaped p-type region has a width of 5 μm to 15 μm.

[0048] Additionally, according to one embodiment of the present invention, the p-type region of the device,

[0049] Carrier concentration is 2x10 19 cm -3 3x10 inland 19 cm -3 There may be a single photon detector characterized by:

[0050]

[0051] To achieve the above technical task, another embodiment of the present invention provides a Lidar receiving sensor.

[0052] The Lidar receiving sensor according to one embodiment of the present invention may be a Lidar receiving sensor characterized by including: an optical receiver to which the above-described single photon detector is applied; and a signal processing unit that analyzes the reception timing of reflected light using a signal output from the optical receiver.

[0053]

[0054] According to one embodiment of the present invention, a single photon detector with improved light detection sensitivity and a method for manufacturing the same can be provided by using a Si lateral pn junction diode having a metal nanostructure formed therein to induce localized surface plasmon resonance (LSPR).

[0055] According to one embodiment of the present invention, by effectively absorbing photons of a wavelength of 905 nm through the LSPR (Localized Surface Plasmon Resonance) phenomenon and amplifying electron-hole pairs generated therefrom through impact ionization, equivalent photosensitivity can be secured even under 24 W pulse conditions, which is about 1 / 5 of the level of a conventional 120 W 905 nm pulse light source.

[0056] According to one embodiment of the present invention, by utilizing the Localized Surface Plasmon Resonance (LSPR) phenomenon to maximize photon absorption in a semiconductor, and by adopting a Si-based lateral pn junction structure, the light absorption and electric field amplification effects for electrons and holes, respectively, can be effectively utilized, thereby maximizing the avalanche phenomenon by impact ionization.

[0057] According to one embodiment of the present invention, an ultra-high sensitivity single photon detector (SPAD) that can operate at a wavelength of 905 nm and has compatibility with a CMOS process can be implemented, so that it can be utilized as a LiDAR light receiving sensor applicable to Level 5 autonomous vehicles.

[0058]

[0059] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims.

[0060]

[0061] Figure 1 is a schematic diagram showing the APD driving band and the difference in avalanche effect between the existing APD and the one produced by this study.

[0062] FIG. 2 is a schematic diagram schematically illustrating the structure of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0063] FIG. 3 is a flowchart schematically illustrating a method for forming a metal nanoprism structure on a PN junction according to one embodiment of the present invention.

[0064] Figure 4 is an image showing a final schematic diagram and energy band diagram of a light receiving sensor product according to one embodiment of the present invention.

[0065] FIG. 5 is a graph showing the results of SIMS depth profiling of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0066] Figure 6 is (a) a topography image showing the surface shape of a horizontal (pn) junction structure formed on a silicon substrate, and (b) an image showing the results of measuring the potential distribution (surface potential) of the corresponding area.

[0067] Figure 7 is a diagram showing (a) the height of the surface measured in a horizontal pn junction structure (topography), (b) the measurement result of the contact potential difference (CPD) at the corresponding location, and (c) the energy level predicted based on the same (energy band diagram).

[0068] FIG. 8 is a graph showing the IV characteristics of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0069] FIG. 9 is a graph showing the results of time-resolved photocurrent (TRPC) measurement of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0070] Figure 10 shows the results of evaluating the electrical characteristics of a Si lateral pn junction device through Mott-Schottky analysis.

[0071] FIG. 11 shows the results of analyzing the change in width of a depletion region according to an electrical bias of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0072] FIG. 12 is an image showing the band structure of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0073] FIG. 13 is an image showing an electric field amplification distribution simulated using the Finite Difference Time Domain (FDTD) method for a metal nanoprism array structure according to an embodiment of the present invention.

[0074] FIG. 14 shows a photocurrent distribution measured using pc-AFM (photoconductive atomic force microscopy) for a photodetector according to an embodiment of the present invention, and is a result of quantitatively confirming the current amplification phenomenon due to the LSPR (Localized Surface Plasmon Resonance) effect.

[0075] Figure 15 is an IV curve comparing the photoresponse characteristics of a bare Si pn diode and a Si pn diode with an Ag prism formed thereon, and shows the current-voltage characteristics under dark conditions (Dark) and light conditions (Light).

[0076]

[0077] Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. It should be understood that all modifications, equivalents, and alternatives included within the spirit and technical scope of the present invention are included.

[0078] In addition, in order to clearly explain the present invention in the drawings, parts unrelated to the description are omitted, and similar parts are given similar drawing reference numerals throughout the specification.

[0079] Throughout the specification, when a part is said to be "connected (connected, contacted, coupled)" to another part, this includes not only cases where it is "directly connected" but also cases where it is "indirectly connected" with another part in between.

[0080] In addition, when it is said that a part such as a layer, film, region, or plate is “on” another part, this includes not only the case where it is “directly above” the other part, but also the case where there is another part in between. In addition, in the present specification, when it is said that a part such as a layer, film, region, or plate is formed on another part, the direction in which it is formed is not limited to the upper direction, but also includes the case where it is formed in the side or lower direction. Conversely, when it is said that a part such as a layer, film, region, or plate is “under” another part, this includes not only the case where it is “directly below” the other part, but also the case where there is another part in between.

[0081] In this specification, the terms "upper surface" and "lower surface" are used as relative concepts to facilitate understanding of the technical concepts of the present invention. Therefore, "upper surface" and "lower surface" do not refer to specific directions, positions, or components, and are interchangeable.

[0082] For example, 'upper surface' can be interpreted as 'lower surface', and 'lower surface' can be interpreted as 'upper surface'. Accordingly, 'upper surface' can be expressed as 'first' and 'lower surface' can be expressed as 'second', or 'lower surface' can be expressed as 'first' and 'upper surface' can be expressed as 'second'. However, within one embodiment, 'upper surface' and 'lower surface' are not used interchangeably.

[0083] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0084] Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0085] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0086]

[0087] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0088] A method for manufacturing a single photon detector according to one embodiment of the present invention is described.

[0089]

[0090] LiDAR (Light Detection and Ranging) technology is being used as a key 3D spatial recognition tool in various fields such as autonomous vehicles, precision mapping, and industrial robots.

[0091] They are generally being developed to operate in the near-infrared (NIR) region, such as 905 nm and 940 nm, or the short-wave infrared (SWIR) region, such as 1550 nm, which are invisible to the human eye.

[0092] Among them, wavelengths of 905 nm to 940 nm can be implemented using CMOS-based sensors, which has the advantage of being advantageous in terms of cost reduction and miniaturization.

[0093] This wavelength has a high risk of retinal damage, so high-power light sources cannot be used, which results in limitations in the measurement distance and sensitivity of LiDAR.

[0094]

[0095] The present invention aims to overcome the above limitations,

[0096] By combining a metal nanostructure capable of inducing the LSPR (Localized Surface Plasmon Resonance) phenomenon with a silicon-based lateral pn junction structure,

[0097]

[0098] The technical features include implementing a LiDAR photoreceiving sensor based on a CMOS process-compatible single photon detector (SPAD) that can secure excellent optical responsivity and quantum efficiency even under low-power near-infrared wavelength conditions around 905 nm.

[0099]

[0100] Figure 1 illustrates the difference between the APD driving band and the avalanche effect of the existing APD and the avalanche effect of this study, and in particular, Figure 1(d) is a schematic diagram explaining the avalanche effect of the structure according to the present invention, and with reference to Figure 1(a), the receiving sensitivity is 10 6 You can see that you are securing excess gain.

[0101] This indicates that the structure is designed to allow photons to reach the avalanche region more quickly and with a higher probability than existing structures, thereby exhibiting high sensitivity even for single photons.

[0102]

[0103] As an example of the above embodiment, the method includes: forming a PN junction having a horizontal p-type region and an n-type region on a substrate; and forming a metal nanoprism structure on the PN junction;

[0104] There may be a method for manufacturing a single photon detector, characterized in that the above metal nanoprism structure induces localized surface plasmon resonance (LSPR) at a wavelength of 900 nm to 1550 nm to increase light absorption of incident photons.

[0105]

[0106] At this time, the metal nanoprism structure refers to a metal structure in which a plurality of triangular or wedge-shaped metal nanopatterns are arranged on a substrate, and each pattern is designed to resonate at a specific wavelength so as to induce localized surface plasmon resonance (LSPR).

[0107]

[0108] As an example of the above embodiment, the step of forming the PN junction is:

[0109] It may be characterized by including a step of forming a p-type region on an n-type silicon substrate; and a step of performing heat treatment on the p-type region to activate doping.

[0110] At this time, the step of forming the p-type region may be characterized by repeatedly arranging a plurality of p-type regions in the form of stripes spaced apart at predetermined intervals on the n-type silicon substrate.

[0111] FIG. 2 is a schematic diagram schematically illustrating the structure of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0112] Referring to Figure 2, the predetermined interval may be characterized as being 25 μm to 35 μm,

[0113] The above stripe-shaped p-type region may be characterized by having a width of 5 μm to 15 μm.

[0114]

[0115] The spacing between the p-type regions and the width of the p-type regions are important in that they can affect the photocurrent generation efficiency and electric field distribution.

[0116] More specifically, if the spacing between the p-type regions is too close, less than 25 μm, there may be a problem in that the electric fields between adjacent p-type regions cause interference, resulting in a non-uniform formation of a depletion region, which reduces the efficiency of collecting electron-hole pairs by photons.

[0117] Conversely, if the gap between the p-type regions is too far, exceeding 35 μm, there may be a problem in that the generated holes are not collected and recombine, resulting in a decrease in photoresponsivity.

[0118] In addition, if the width of the p-type region is too narrow, less than 5 μm, there may be a problem in that sufficient doping and electric field formation may be difficult, and thus optical amplification may be insufficient under avalanche driving conditions.

[0119] Conversely, if the width of the p-type region is too wide, exceeding 15 μm, there may be a problem in that the depletion region does not extend uniformly across the entire device, thereby reducing the detection sensitivity for single photons.

[0120]

[0121] In addition, as an example of the above embodiment, the step of forming the p-type region is,

[0122] It may be characterized by including a step of defining a doping region by performing a photolithography process on an n-type silicon substrate; and a step of ion implanting a p-type dopant into the doping region.

[0123]

[0124] At this time, the p-type dopant may include at least one selected from the group consisting of boron (B), aluminum (Al), gallium (Ga), and indium (In).

[0125]

[0126] The step of ion implanting the above p-type dopant is to determine the doping concentration of the p-type dopant (atoms / cm 3 ) is 10 15 cm -3 10 inland 19 cm -3 It can be characterized by being within the scope of

[0127] The doping concentration of the above P-type dopant is important in that it directly affects the electrical properties of the p-type region, carrier concentration, and subsequent avalanche effect.

[0128] More specifically, the doping concentration of the P-type dopant is 10 15 cm -3 If it is less than , there may be a problem in that sufficient hole density is not secured, so the p-type region is weakly formed, and accordingly, the formation of electric field and expansion of depletion region are limited, resulting in a decrease in photoresponsivity.

[0129] Conversely, the doping concentration of the P-type dopant is 10 19 cm -3 If it exceeds, there may be problems such as reduced reliability, increased noise due to increased dark count rate, and reduced timing resolution due to shortened drift length.

[0130]

[0131] In addition, the step of ion implanting the p-type dopant may be characterized in that the implantation energy is 40 keV to 60 keV.

[0132] The above injection energy is important in that it directly affects the depth and electric field distribution of the formed junction, and further, the breakdown voltage characteristics of the device, by determining the injection depth of the dopant.

[0133] More specifically, if the above-mentioned injection energy is less than 40 keV, there may be a problem in that the dopant is injected into too shallow an area and is lost after heat treatment, or the junction depth is not sufficiently secured, so the electric field is not concentrated and it becomes difficult to optimize the breakdown characteristics.

[0134] Conversely, if the above-mentioned implantation energy exceeds 60 keV, there may be a problem in that the dopant is implanted too deeply, causing the depletion region to deviate from the center and the electric field distribution to be dispersed, which may result in the conditions required for avalanche formation not being met, thereby lowering the sensitivity and response speed of the device.

[0135]

[0136] In addition, as an example of the above embodiment, the step of activating the doping may be characterized by performing heat treatment at a temperature range of 1000°C to 1100°C for 20 to 40 minutes.

[0137]

[0138] The heat treatment temperature in the step of activating the above doping is important in that it directly affects the activation efficiency of the dopant and the bonding characteristics.

[0139] If the above heat treatment temperature is less than 1000°C, there may be a problem in that the injected dopant is not sufficiently activated, resulting in a low hole concentration, which may increase the junction resistance and deteriorate the electrical characteristics of the device.

[0140] Conversely, if the heat treatment temperature exceeds 1100°C, the diffusion of the dopant may proceed excessively, causing the junction to become deep and the electric field distribution to become blurred, which may result in a problem of deterioration in the breakdown voltage and response characteristics of the device.

[0141]

[0142] In addition, if the heat treatment time is less than 20 minutes, there may be a problem in that the activation of the dopant is insufficient, so that sufficient hole concentration cannot be secured, which may result in an increase in junction resistance and a decrease in the sensitivity of the device.

[0143] Conversely, if the heat treatment time exceeds 40 minutes, the diffusion of the dopant may proceed excessively, causing the bonding boundary to become unclear and the electric field concentration to decrease, which may result in a problem of deterioration in the breakdown characteristics and response speed of the device.

[0144]

[0145] FIG. 3 is a flowchart schematically illustrating a method for forming a metal nanoprism structure on a PN junction according to one embodiment of the present invention.

[0146]

[0147] Referring to FIG. 3, as an example of the above embodiment, the step of forming the metal nanoprism structure is:

[0148] It may be characterized by including a step of transferring a polystyrene bead onto the PN junction; a step of depositing a metal entirely on the PN junction to which the polystyrene bead has been transferred; and a step of removing the polystyrene bead to form a metal nanoprism pattern.

[0149]

[0150] As described above, when metal is deposited entirely on the PN junction where the polystyrene beads are applied, by subsequently removing the polystyrene beads, metal is deposited in the area between the polystyrene beads.

[0151] The area occupied by the above polystyrene beads is not deposited with metal, so that the metal can ultimately be deposited in the form of a nanoprism.

[0152]

[0153] At this time, the diameter size of the polystyrene beads may be characterized as being 100 μm to 500 μm, and the size of the deposited nanoprism can be controlled by controlling the diameter size of the polystyrene beads.

[0154]

[0155] More preferably, the size of the polystyrene beads may be characterized by a diameter range of 100 μm to 500 μm,

[0156] When the diameter size of the above polystyrene beads is in the range of 100 μm to 500 μm as described above, the nanoprism can have a length of 200 nm to 250 nm.

[0157] At this time, the length of the nanoprism is defined as the average length of the sides constituting the prism,

[0158] The length of the above nanoprism is an important factor as it is directly related to the range of resonant wavelengths that can be secured.

[0159] That is, as an example of the above embodiment, the nanoprism may be characterized by having a length of 200 nm to 250 nm,

[0160] When the length of the nanoprism is in the range of 200 nm to 250 nm as described above, localized surface plasmon resonance (LSPR) can be induced at a wavelength of 900 nm to 1550 nm.

[0161]

[0162] At this time, the step of depositing the metal may be characterized by depositing a metal including at least one selected from the group consisting of silver (Ag), gold (Au), copper (Cu), and graphene quantum dots (GQDs), but is not limited to the materials described above.

[0163]

[0164] In addition, the step of depositing the metal may be characterized by depositing the metal to a thickness of 10 nm to 100 nm.

[0165] The deposition thickness of the above metal is important in that it controls the thickness of the formed metal nanoprism structure to effectively induce the LSPR (Localized Surface Plasmon Resonance) phenomenon.

[0166] More specifically, if the thickness of the metal to be deposited is less than 10 nm, there may be a problem in that the metal layer may not form a continuous pattern but may be formed in a disconnected or non-uniform shape, so that the desired nanoprism structure may not be implemented, and thus the reproducibility of the plasmon resonance may be reduced.

[0167] Conversely, if the thickness of the metal to be deposited exceeds 100 nm, the metal layer exceeds the penetration depth of light, so the plasmon resonance is dissipated inside the metal, and as a result, the local electric field enhancement effect due to LSPR is suppressed, which is undesirable because the light absorption efficiency is reduced.

[0168]

[0169] The step of depositing the above metal may be characterized in that it is performed by one or more deposition methods selected from the group consisting of an evaporation method, sputtering, an island formation method through heat treatment after thin film deposition, etc., but is not limited to the above-described methods.

[0170]

[0171] In addition, as an example of the above embodiment, the step of transferring the Polystyrene Bead is,

[0172] It may be characterized by including a step of dividing the PN junction into a plurality of regions; and a step of transferring polystyrene beads of different diameter sizes to each of the divided regions.

[0173]

[0174] As described above, by forming multiple regions in which polystyrene beads of different diameters are each arranged on the PN junction, an excellent effect of forming a multi-wavelength resonance wavelength can be obtained.

[0175] At this time, the number of the plurality of areas may be two or more, and can be adjusted as needed, and is not limited to a specific number.

[0176]

[0177] In addition, as an example of the above embodiment, the step of transferring the Polystyrene Beads of different diameter sizes is,

[0178] It is performed by selectively transferring polystyrene beads having different diameters to each partitioned area, or

[0179] Alternatively, after transferring Polystyrene Beads of the same diameter to the entire area,

[0180] This can be done in a way that for each partitioned area, the polystyrene beads in that area are partially worn away so that they have different diameters.

[0181]

[0182] In performing the above steps, a mask may be used as needed,

[0183] At this time, the above-mentioned wearing step can be performed by, for example, a plasma treatment process, an oxidation process, or a heat treatment process.

[0184]

[0185]

[0186] A single photon detector according to another embodiment of the present invention is described.

[0187]

[0188] Since the above single photon detector is an invention of a different category that shares the core of a technical idea that is substantially the same as the above single photon detector manufacturing method,

[0189] The above-mentioned content can be applied as is when explaining the method for manufacturing the single photon detector.

[0190]

[0191] As an example of the above embodiment, a PN junction comprising a p-type region and an n-type region arranged horizontally on a substrate; and a metal nanoprism structure formed on the PN junction,

[0192] The above metal nanoprism structure may have a single photon detector characterized in that it induces localized surface plasmon resonance (LSPR) at a wavelength of 900 nm to 1550 nm to increase light absorption of incident photons.

[0193]

[0194] As described above, the PN junction may have a structure in which a plurality of p-type regions in the form of stripes are repeatedly arranged at predetermined intervals on an n-type silicon substrate.

[0195] At this time, the predetermined interval may be characterized as being 25 μm to 35 μm,

[0196] The above stripe-shaped p-type region may be characterized by having a width of 5 μm to 15 μm.

[0197]

[0198] Additionally, the p-type region of the device has a carrier concentration of 2x10 19 cm -33x10 inland 19 cm -3 It can be characterized by being.

[0199]

[0200] Referring to FIG. 4, a final schematic diagram and energy band diagram of a light receiving sensor product according to an embodiment of the present invention can be confirmed.

[0201]

[0202] In addition, a Lidar receiving sensor according to another embodiment of the present invention is described.

[0203]

[0204] As an example of the above embodiment, there may be a Lidar receiving sensor characterized by including an optical receiver to which the above-described single photon detector is applied; and a signal processing unit that analyzes the reception timing of reflected light using a signal output from the optical receiver.

[0205]

[0206] Since the above Lidar receiving sensor is an invention of a different category that shares the core of a technical idea that is substantially the same as the above single photon detection device,

[0207] The above-mentioned content can be applied as is when explaining the single photon detector above.

[0208]

[0209] Manufacturing Example 1. Manufacturing of a single photon detector according to an embodiment of the present invention.

[0210]

[0211] 1. Si lateral pn junction diode manufacturing steps.

[0212]

[0213] First, the lateral pn junction process was performed on a Si wafer through photolithography and ion implantation.

[0214] At this time, a 30 μm pitch and a 10 μm length of p-type region were secured through photolithography using an n-type Si wafer, and at this time, boron 1 x 10 was used as a dopant for p-type. 15 cm -2 (Injection dose) was injected through ion implantation with 50 keV energy, and the activation process was performed at 1050°C for 30 minutes.

[0215]

[0216] 2. Step of forming LSPR structure on the above diode.

[0217]

[0218] A structure capable of emitting plasmonic hot charges was fabricated through nanolithography in the above diode.

[0219] After transferring a polystyrene (PS) bead to the above pn junction diode, Ag was deposited using the evaporation method, and then the PS bead was removed.

[0220] As a result, Ag was deposited between the beads, and no deposition occurred where the beads were, so a prism-shaped metal was deposited on the surface of the pn junction diode.

[0221] Accordingly, a prism with a length of 220 nm could be formed, through which a resonance wavelength of 900 nm could be secured.

[0222]

[0223]

[0224] Experimental Example 1. Analysis of Si lateral pn junction diode.

[0225]

[0226] The above experimental example 1 is described with reference to FIGS. 5 to 12.

[0227]

[0228] FIG. 5 is a graph showing the results of SIMS depth profiling of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0229] Referring to the above Figure 5, the actual concentration distribution of boron and the simulation results can be compared. The measurement results show that boron is diffused to a depth of about 520 nm, and at most about 2.5x10 near the surface. 19 cm -3 A high concentration distribution was confirmed, showing that p-type doping was successfully achieved.

[0230]

[0231] Figure 6 is (a) a topography image showing the surface shape of a horizontal (pn) junction structure formed on a silicon substrate, and (b) an image showing the results of measuring the potential distribution (surface potential) of the corresponding area.

[0232] Referring to the topography image of the above figure 6(a), p + The type region is formed in a stripe shape in the center, and a structural boundary can be confirmed that distinguishes it from the n-type regions on the left and right.

[0233] Also, referring to the surface potential image of the above Fig. 6(b), p + The potential difference between the n-type region and the n-type region is visually observed using Kelvin Probe Force Microscopy (KPFM), which verifies the successful formation of a horizontal pn junction.

[0234]

[0235] Figure 7 is a diagram showing (a) the height of the surface measured in a horizontal pn junction structure (topography), (b) the measurement result of the contact potential difference (CPD) at the corresponding location, and (c) the energy level predicted based on the same (energy band diagram).

[0236]

[0237] Referring to the above Fig. 7(a), the change in the surface height of the p-type region and n-type region defined in the horizontal direction can be confirmed using an atomic force microscope (AFM), indicating that the p-type region in the center has been specifically formed.

[0238] Referring to the above Fig. 7(b), the CPD results measured through Kelvin force microscopy (KPFM) clearly show the difference in potential between the p-type region and the n-type region, which allows us to determine the difference in work function of each region ( n-Si = about 4.255 eV, p-Si = approximately 4.312 eV) can be quantitatively analyzed.

[0239] Referring to the above Figure 7(c), the predicted energy level configuration based on the measurement results is shown, and a band gap energy of approximately 1.12 eV can be confirmed from the difference in the positions of the conduction band (CB) and valence band (VB) between the p-type region and the n-type region.

[0240] Through this, we can confirm that the pn junction has been successfully secured.

[0241]

[0242] FIG. 8 is a graph showing the IV characteristics of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0243] Figure 8(b) shows a comparison of IV characteristics in both dark and light conditions, and Figure 8(a) shows an enlarged view of a portion of the IV graph in the dark condition.

[0244] Referring to the above Fig. 8(a), the IV curve measured in a dark room condition shows the forward bias characteristics of a typical diode, and it can be confirmed that a pn junction diode was successfully formed through the rapid current increase at a voltage of about 0.5 V or higher.

[0245] In addition, referring to the above Fig. 8(b), the difference between the curves in the dark state (Dark) and the light state (Light) is clearly shown in the reverse bias region below -0.4 V.

[0246] This means that electron-hole pairs generated by photons under illumination conditions contributed to the current increase.

[0247] Through this, it can be confirmed that the present structure has photoresponsiveness and can be utilized as a light sensor or single photon detector (SPAD).

[0248]

[0249] FIG. 9 is a graph showing the results of time-resolved photocurrent (TRPC) measurement of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0250] Referring to Fig. 9, the light source was periodically turned ON / OFF for the Si lateral pn junction diode, and the response characteristics of the photocurrent over time were measured as a result.

[0251] When the light source is turned on, a photocurrent of approximately 1.1 μA is immediately generated and maintained stably, and when turned off, a dark current converging to 0 is observed, confirming that this device has excellent photoresponsivity and repeatable operation stability.

[0252]

[0253] Figure 10 shows the results of evaluating the electrical characteristics of a Si lateral pn junction device through Mott-Schottky analysis.

[0254] The above figure 10(a) shows the reciprocal square of the electrostatic capacitance according to the reverse voltage (1 / C 2 ) and voltage (V), which can be used to estimate the intrinsic potential and doping concentration of the device. From the linear fitting results, the intrinsic potential was derived as approximately 0.88 V, suggesting that the device has ideal pn junction characteristics.

[0255] In addition, Fig. 10(b) shows the results of the above analysis, N A , N D concentration and built-in potential, E F, n You can check the formula that derives the value.

[0256]

[0257] FIG. 11 shows the results of analyzing the change in width of a depletion region according to an electrical bias of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0258] Referring to Fig. 11(a), it can be seen that the thickness of the depletion region tends to increase as the negative bias increases.

[0259] This is a typical electrical characteristic of a pn junction diode, suggesting that as the reverse bias voltage increases, the charge separation region widens, which can improve the photoresponse.

[0260] In addition, Fig. 11(b) can confirm the theoretical calculation formula for the width of the depletion region based on the above analysis results.

[0261]

[0262] FIG. 12 is an image showing the band structure of a PN junction (Si lateral pn junction diode) formed according to one embodiment of the present invention.

[0263] The above figure 12 suggests that the intrinsic potential was formed to be approximately 0.88 eV and the depletion layer width to be 2.7 μm, thereby confirming that the formation of an electrical structure suitable for single photon detection of the device according to the present invention was successfully achieved.

[0264]

[0265]

[0266] Experimental Example 2. Analysis of LSPR structure through metal nanoprism nanolithography.

[0267]

[0268] The above experimental example 2 is described with reference to FIGS. 13 to 15.

[0269]

[0270] FIG. 13 is an image showing an electric field amplification distribution simulated using the Finite Difference Time Domain (FDTD) method for a metal nanoprism array structure according to an embodiment of the present invention.

[0271] Referring to Figure 13, a strong local electric field amplification phenomenon near the metal surface and particle boundaries due to the LSPR effect can be confirmed.

[0272]

[0273] FIG. 14 shows a photocurrent distribution measured using pc-AFM (photoconductive atomic force microscopy) for a photodetector according to an embodiment of the present invention, and is a result of quantitatively confirming the current amplification phenomenon due to the LSPR (Localized Surface Plasmon Resonance) effect.

[0274] Referring to Figure 14, it can be confirmed that charge transport and injection efficiency due to LSPR is improved through a localized increase in current upon light irradiation in an area where a metal nanostructure is formed.

[0275]

[0276] Figure 15 is an IV curve comparing the photoresponse characteristics of a bare Si pn diode and a Si pn diode with an Ag prism formed thereon, and shows the current-voltage characteristics under dark conditions (Dark) and light conditions (Light).

[0277] Referring to the above Figure 15, it can be confirmed that in the case of a specimen with an Ag prism structure introduced, the photocurrent increases by about 100 times or more compared to the bare structure when irradiated with light. This is the result of the electric field amplification effect due to the LSPR (Localized Surface Plasmon Resonance) phenomenon greatly improving the photoresponsivity.

[0278]

[0279] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0280] The scope of the present invention is indicated by the claims described below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. A step of forming a PN junction having a horizontal p-type region and an n-type region on a substrate; and A step of forming a metal nanoprism structure on the above PN junction; including, A method for manufacturing a single photon detector, characterized in that the above metal nanoprism structure induces localized surface plasmon resonance (LSPR) at a wavelength of 900 nm to 1550 nm to increase light absorption of incident photons.

2. In the first paragraph, the step of forming the PN junction is: A step of forming a p-type region on an n-type silicon substrate; and A method for manufacturing a single photon detector, characterized in that it comprises a step of activating doping by performing heat treatment on the p-type region.

3. In the second paragraph, the step of forming the p-type region is: A method for manufacturing a single photon detector, characterized in that a plurality of p-type regions in the form of stripes spaced at predetermined intervals are repeatedly arranged on the n-type silicon substrate.

4. A method for manufacturing a single photon detector, characterized in that in the third paragraph, the predetermined interval is 25 μm to 35 μm.

5. A method for manufacturing a single photon detector, characterized in that in the third paragraph, the p-type region in the stripe shape has a width of 5 μm to 15 μm.

6. In the third paragraph, the step of forming the p-type region is: A step of defining a doping region by performing a photolithography process on an n-type silicon substrate; and A method for manufacturing a single photon detector, characterized in that it comprises a step of ion implanting a p-type dopant into the above doping region.

7. In the 6th paragraph, the step of ion-implanting the p-type dopant is, The doping concentration of P-type dopant is 10 15 cm -2 10 inland 19 cm -2 A method for manufacturing a single photon detector, characterized in that it has a range of .

8. In the 6th paragraph, the step of ion-implanting the p-type dopant is, A method for manufacturing a single photon detector, characterized in that the injection energy is 40 keV to 60 keV.

9. In the second paragraph, the step of activating the doping is: A method for manufacturing a single photon detector, characterized in that heat treatment is performed in a temperature range of 1000°C to 1100°C.

10. In the first paragraph, the step of forming the metal nanoprism structure is: A step of transferring a polystyrene bead onto the above PN junction; A step of depositing metal entirely on the PN junction to which the above polystyrene beads are transferred; and A method for manufacturing a single photon detector, characterized by comprising a step of forming a metal nanoprism pattern by removing the above polystyrene beads.

11. In the 10th paragraph, the step of depositing the metal is: A method for manufacturing a single photon detector, characterized by depositing a metal including at least one selected from the group consisting of silver (Ag), gold (Au), copper (Cu), ruthenium (Ru), and graphene quantum dots (GQDs).

12. In the 10th paragraph, the step of depositing the metal is: A method for manufacturing a single photon detector, characterized in that it is performed by using at least one deposition method selected from the group consisting of an evaporation method, a sputtering method, and an island formation method through heat treatment after thin film deposition.

13. In the 10th paragraph, the step of transferring the polystyrene beads is, A step of dividing the above PN junction into a plurality of regions; and A method for manufacturing a single photon detector, characterized by comprising a step of transferring polystyrene beads of different diameter sizes to each of the above-mentioned partitioned areas.

14. A PN junction consisting of a p-type region and an n-type region arranged horizontally on the substrate; and A metal nanoprism structure formed on the PN junction; including, A single photon detector characterized in that the above metal nanoprism structure induces localized surface plasmon resonance (LSPR) at a wavelength of 900 nm to 1550 nm to increase light absorption of incident photons.

15. In the 14th paragraph, the PN junction, A single photon detector characterized by a structure in which a plurality of p-type regions in the form of stripes are repeatedly arranged at predetermined intervals on an n-type silicon substrate.

16. A single photon detector according to claim 15, wherein the predetermined interval is 25 μm to 35 μm.

17. A single photon detector according to claim 15, characterized in that the stripe-shaped p-type region has a width of 5 μm to 15 μm.

18. In the 14th paragraph, the p-type region of the device is Carrier concentration is 2x10 19 cm -3 3x10 inland 19 cm -3 A single photon detector characterized by:

19. An optical receiver to which the single-photon detector of Article 14 is applied; and A Lidar receiving sensor characterized by including a signal processing unit that analyzes the reception timing of reflected light using a signal output from the optical receiver.

Images