KR20230092458A - nBn structure based Mid-Infrared Photodetector, and Manufacturing Method thereof - Google Patents

Abstract

The present invention relates to a mid-infrared photodetector using an nBn structure and a manufacturing method thereof and, more specifically, to a mid-infrared photodetector using an nBn structure and a manufacturing method thereof, wherein the material for implementing the nBn structure can be selected from a wider range, and a dark current is effectively suppressed to improve detection performance. The method includes the steps of: forming a first absorption layer; forming a barrier layer; and forming a second absorbing layer.

Description

Mid-infrared photodetector using nBn structure and manufacturing method thereof {nBn structure based Mid-Infrared Photodetector, and Manufacturing Method thereof}

The present invention relates to a mid-infrared photodetector using an nBn structure and a method for manufacturing the same, and more particularly, materials for realizing the nBn structure can be selected from a wider variety of widths, and dark current is effectively suppressed to improve detection performance. It relates to a mid-infrared photodetector using an nBn structure and a manufacturing method thereof.

A mid-infrared photodetector is a photodetector operating in a mid wavelength infrared (MWIR) band of 3 to 5 micrometers, and can be used in special environments such as fire sites, seabed detection, and wartime situations. In most of the mid-infrared photodetectors, device performance may deteriorate due to dark current generated by factors such as diffusion current and dark current due to generation-recombination.

In order to reduce such a dark current, Non-Patent Document 1 discloses a method of doping a specific material on a part of an absorption layer of a mid-infrared photodetector. This can reduce the dark current by about 10%. However, since the dark current can also be generated by heat, preparation for this is also required.

Non-Patent Document 2 discloses a mid-infrared photodetector having an nBn structure in which a barrier layer having a large bandgap is formed between two n-absorption layers. 1 schematically shows the energy band of a conventional nBn structure. As shown in FIG. 1, in the conventional nBn structure, the valence bands (Ev) of the n-absorption layer and the barrier layer have energy levels corresponding to each other, and the conduction band (Ec) of the barrier layer has a relatively high energy level compared to the conduction band of the n-absorption layer. It may have an energy band having When a reverse bias is applied to the mid-infrared photodetector, holes can move freely in the valence band, whereas electrons can be restricted by the barrier layer. That is, the mid-infrared photodetector having the nBn structure can structurally remove the diffusion current and the dark current due to generation-recombination.

Meanwhile, in order to implement a mid-infrared photodetector having an nBn structure, it is preferable to consider both lattice constants and valence band energy levels of materials forming the n-absorption layer and the barrier layer. 2 schematically shows the lattice constants and energy levels of materials capable of realizing a conventional nBn structure. Specifically, FIG. 2(a) schematically shows lattice constants and energy levels of materials capable of realizing a conventional nBn structure, and FIG. 2(b) is an alignment table of lattice constants, work functions, and band gaps of each semiconductor material. shows schematically. As such, the conventional nBn structure can use only relatively limited materials as shown in FIG. 2, so it is difficult to control the thickness of the nBn structure and has difficulty in commercialization despite excellent device performance due to its relatively low practicality.

That is, there is a need for research into a device having excellent detection performance while allowing more diverse selection of materials for realizing the nBn structure.

B. M. Nguyen1, D. Hoffman1, P. Y. Delaunay1, E. K. W. Huang1, M. Razeghi1, and J. Pellegrino, Appl. Phys. Lett. 93, 163502 (2008) S. Maimon and G. W. Wicks, Appl. Phys. Lett. 89, 151109 (2006)

An object of the present invention is to provide a mid-infrared photodetector using an nBn structure and a method for manufacturing the same, which can select materials for realizing the nBn structure from a wider range and improve detection performance by effectively suppressing dark current. .

In order to solve the above problems, one embodiment of the present invention is a method of manufacturing a mid-infrared photodetector using an nBn structure, comprising: forming a 1n absorbing layer with a first material having a band gap of 0.9eV or less; mixing the first material and the second material on the upper surface of the 1n absorption layer, forming a barrier layer in such a manner that a ratio of the first material decreases and a ratio of the second material increases toward the upper side; and forming a 2n absorbing layer of the first material on the upper surface of the barrier layer.

In some embodiments of the present invention, the difference between the lattice constant of the second material and the lattice constant of the first material may be within 0.2 Å.

In some embodiments of the present invention, the energy level of the conduction band of the second material may be higher than the energy level of the valence band of the second material.

In some embodiments of the present invention, when the first material is InAs, the second material is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb, and when the first material is InAsSb, the second material is AlSb. , InAlSb, AlAsSb, and InAlAsSb, and when the first material is InSb, the second material may be any one of AlSb, InAlSb, AlAsSb, InAlAsSb, and GaAsSb.

In some embodiments of the present invention, the forming of the barrier layer may include a first e-fusion cell accommodating the first material and a second e-fusion cell accommodating the second material by using a molecular beam epitaxy process. In a state in which each shutter is fully opened, the barrier layer may be formed in such a manner that the temperature of the heater of the first e-fusion cell decreases or is maintained while going upward, and the temperature of the heater of the second e-fusion cell increases. .

In some embodiments of the present invention, the forming of the barrier layer may include a first e-fusion cell accommodating the first material and a second e-fusion cell accommodating the second material by using a molecular beam epitaxy process. With each heater temperature set to a preset temperature, the barrier layer is formed in such a way that the aperture ratio of the shutter of the first e-fusion cell decreases and the aperture ratio of the shutter of the second e-fusion cell increases as it goes upward. can form

In order to solve the above problems, one embodiment of the present invention is a method of manufacturing a mid-infrared photodetector using an nBn structure, comprising: forming a 1n absorbing layer with a first material having a band gap of 0.9 eV or less; mixing a second material and a third material on an upper surface of the 1n absorption layer, forming a barrier layer in such a manner that a ratio of the second material decreases and a ratio of the third material increases toward the top; and forming a 2n absorbing layer of the first material on the upper surface of the barrier layer.

In some embodiments of the present invention, a difference between the energy level of the valence band of the second material and the energy level of the valence band of the first material may be within 2.0 eV.

In some embodiments of the present invention, the difference between the lattice constant of the third material and the lattice constant of the first material may be within 0.2 Å.

In some embodiments of the present invention, the energy level of the conduction band of the second material is higher than that of the valence band of the second material, and the energy level of the conduction band of the third material is higher than that of the valence band of the third material. may be higher than the level.

In some embodiments of the present invention, when the first material is InAs, each of the second material and the third material is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb, and when the first material is InAsSb, When each of the second material and the third material is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb, and the first material is InSb, each of the second material and the third material is AlSb, InAlSb, AlAsSb, It may be any one of InAlAsSb and GaSb.

In some embodiments of the present invention, the forming of the barrier layer may include a second e-fusion cell accommodating the second material and a third e-fusion cell accommodating the third material by using a molecular beam epitaxy process. In a state in which each shutter is completely open, the barrier layer may be formed in such a manner that a temperature of the heater of the second e-fusion cell decreases and a temperature of the heater of the third e-fusion cell increases toward the upper side.

In some embodiments of the present invention, the forming of the barrier layer may include a second e-fusion cell accommodating the second material and a third e-fusion cell accommodating the third material by using a molecular beam epitaxy process. With each heater temperature set to a predetermined temperature, the barrier layer is formed in such a way that the aperture ratio of the shutter of the second e-fusion cell decreases and the aperture ratio of the shutter of the third e-fusion cell increases as it goes upward. can form

According to an embodiment of the present invention, by implementing the nBn structure using more diverse materials, it is possible to realize an effect capable of implementing a mid-infrared photodetector suitable for commercialization while having excellent detection performance.

According to an embodiment of the present invention, by forming the barrier layer in a special way, the barrier layer can be matched with the n-absorption layer even without considering both the lattice constant and the valence band energy level, and the material forming the n-absorption layer and the barrier layer It can exert the effect of expanding the degree of freedom of selection for .

According to an embodiment of the present invention, it is possible to achieve an effect of improving a signal-to-noise ratio by suppressing dark current by the nBn structure including the barrier layer.

1 schematically shows the energy band of a conventional nBn structure.
2 schematically shows the lattice constants and energy levels of materials capable of realizing a conventional nBn structure.
3 schematically illustrates a manufacturing method of a mid-infrared photodetector according to an embodiment of the present invention.
4 conceptually illustrates an nBn structure according to an embodiment of the present invention.
5 conceptually illustrates an nBn structure according to an embodiment of the present invention.
6 schematically shows equipment for performing a molecular beam epitaxy process according to an embodiment of the present invention.
7 schematically illustrates a relationship between time and heater temperature of a first e-fusion cell and a second e-fusion cell according to an embodiment of the present invention.
8 schematically illustrates a relationship between time and shutter aperture ratio of a first e-fusion cell and a second e-fusion cell according to an embodiment of the present invention.

In the following, various embodiments and/or aspects are disclosed with reference now to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to facilitate a general understanding of one or more aspects. However, it will also be appreciated by those skilled in the art that such aspect(s) may be practiced without these specific details. The following description and accompanying drawings describe in detail certain illustrative aspects of one or more aspects. However, these aspects are exemplary and some of the various methods in principle of the various aspects may be used, and the described descriptions are intended to include all such aspects and their equivalents.

Moreover, various aspects and features will be presented by a system that may include a number of devices, components and/or modules, and the like. It should also be noted that various systems may include additional devices, components and/or modules, and/or may not include all of the devices, components, modules, etc. discussed in connection with the figures. It must be understood and recognized.

"Example", "example", "aspect", "exemplary", etc., used herein should not be construed as preferring or advantageous to any aspect or design being described over other aspects or designs. .

In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless otherwise specified or clear from the context, “X employs A or B” is intended to mean one of the natural inclusive substitutions. That is, X uses A; X uses B; Or, if X uses both A and B, "X uses either A or B" may apply to either of these cases. Also, the term "and/or" as used herein should be understood to refer to and include all possible combinations of one or more of the listed related items.

Also, the terms "comprises" and/or "comprising" mean that the feature and/or element is present, but excludes the presence or addition of one or more other features, elements and/or groups thereof. It should be understood that it does not.

In addition, terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

In addition, terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "include" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

In addition, in the embodiments of the present invention, unless otherwise defined, all terms used herein, including technical or scientific terms, are generally understood by those of ordinary skill in the art to which the present invention belongs. has the same meaning as 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 unless explicitly defined in the embodiments of the present invention, an ideal or excessively formal meaning not be interpreted as

3 schematically shows a manufacturing method of the mid-infrared photodetector 1 according to an embodiment of the present invention.

A method of manufacturing a mid-infrared photodetector 1 using an nBn structure according to an embodiment of the present invention, comprising: forming a 1n absorbing layer of a first material 100 having a band gap of 0.9eV or less (S100); The first material 100 and the second material 200 are mixed on the upper surface of the 1n absorption layer, but the ratio of the first material 100 decreases and the ratio of the second material 200 increases toward the upper side. Forming a barrier layer in an increasing form (S200); and forming a 2n absorbing layer with the first material 100 on the upper surface of the barrier layer (S300).

In the step of forming the 1n absorbing layer (S100), in an embodiment of the present invention, the 1n absorbing layer may be formed of the first material 100 having a band gap of 0.9 eV or less. In addition, in the step of forming the 2n absorbing layer (S300), in an embodiment of the present invention, a 2n absorbing layer may be formed of the first material 100 on the upper surface of the barrier layer.

The first material 100 may have a band gap of 0.9 eV or less, preferably 0.5 eV or less. In addition, the first material 100 may be any one of InAs, InAsSb, InSb, and a mixture thereof.

Meanwhile, in the prior art, when materials for the n-absorption layer and the barrier layer implementing the nBn structure are selected, materials having little difference are selected in consideration of both the lattice constant and the valence band energy level of the material. However, since the number of materials having similar lattice constants and similar valence band energy levels is very limited, the conventional nBn structure has a problem in that it is difficult to control the thickness of the n-absorption layer and its practicality is relatively low.

In order to solve this problem, in the present invention, a barrier layer was formed in a special shape on the upper surface of the 1n absorption layer.

Preferably, in the step of forming the barrier layer according to an embodiment of the present invention (S200), the first material 100 and the second material 200 are mixed on the upper surface of the 1n absorption layer, but the upper side The barrier layer may be formed in such a manner that the ratio of the first material 100 decreases and the ratio of the second material 200 increases as . At this time, the second material 200 is preferably different from the first material 100. For example, the barrier layer is made of 100% of the ratio of the first material 100 at a point in contact with the 1n absorbing layer, and the first material 100 at a midpoint between the 1n absorbing layer and the 2n absorbing layer. The ratio of 1 material 100 is 50%, the ratio of the second material 200 is 50%, and the ratio of the second material 200 at a point in contact with the 2n absorption layer is 100 % can be made.

According to this manufacturing method, the barrier layer can form lattice matching with the 1n absorbing layer even without considering both the lattice constant and the valence band energy level. In one embodiment of the present invention, the second material 200 forming the barrier layer has a valence band energy level while considering a difference in lattice constant from the first material 100 forming the 1n absorption layer. The difference may not be considered, or both the difference in lattice constant and the difference in valence band energy level from the first material 100 may not be considered.

Preferably, in one embodiment of the present invention, the difference between the lattice constant of the second material 200 and the lattice constant of the first material 100 may be within 0.2 Å.

In addition, in the manufacturing method of the mid-infrared photodetector 1 using the nBn structure according to another embodiment of the present invention, the second material 200 and the third material 300 are mixed on the upper surface of the 1n absorbing layer. However, forming a barrier layer in such a way that the ratio of the second material 200 decreases and the ratio of the third material 300 increases toward the upper side (S200); may include. At this time, it is preferable that the second material 200 and the third material 300 are different from each other. For example, the barrier layer is made of 100% of the ratio of the second material 200 at a point in contact with the 1n absorbing layer, and the first at the midpoint between the 1n absorbing layer and the 2n absorbing layer. The ratio of the two materials 200 is 50%, the ratio of the third material 300 is 50%, and the ratio of the third material 300 at a point in contact with the 2n absorption layer is 100%. % can be made.

According to this manufacturing method, the barrier layer can form lattice matching with the 1n absorbing layer even without considering both the lattice constant and the valence band energy level. In one embodiment of the present invention, the valence band energy of the second material 200 forming the barrier layer does not take into account the difference in lattice constant from the first material 100 forming the 1n absorption layer. The difference in level may be considered, or both the difference in lattice constant and the difference in valence band energy level from the first material 100 may not be considered.

Preferably, in an embodiment of the present invention, a difference between the energy level of the valence band of the second material 200 and the energy level of the valence band of the first material 100 may be within 2.0 eV. At this time, it is preferable that the first material 100 is InAs and the second material 200 is AlSb.

In addition, according to this manufacturing method, the barrier layer can form lattice matching with the 2n absorbing layer even without considering both the lattice constant and the valence band energy level. In one embodiment of the present invention, the third material 300 forming the barrier layer has a valence band energy level while considering a difference in lattice constant from the first material 100 forming the 2n absorption layer. The difference may not be considered, or both the difference in lattice constant and the difference in valence band energy level from the first material 100 may not be considered.

Preferably, in one embodiment of the present invention, the difference between the lattice constant of the third material 300 and the lattice constant of the first material 100 may be within 0.2 Å. At this time, it is preferable that the first material 100 is InAs and the third material 300 is AlSb.

As described above, by forming the barrier layer in a special way in one embodiment of the present invention, the barrier layer can be matched with the n-absorption layer even without considering both the lattice constant and the valence band energy level, and the n-absorption layer and the barrier layer It can exert the effect of expanding the degree of freedom of selection for the material to be formed.

Preferably, in one embodiment of the present invention, when the first material 100 is InAs, the second material 200 is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb, and the first material ( 100) is InAsSb, the second material 200 is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb, and when the first material 100 is InSb, the second material 200 is AlSb, It may be any one of InAlSb, AlAsSb, InAlAsSb, and GaAsSb.

Further, in another embodiment of the present invention, when the first material 100 is InAs, each of the second material 200 and the third material 300 is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb. one, and when the first material 100 is InAsSb, each of the second material 200 and the third material 300 is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb, and the first material ( 100) is InSb, each of the second material 200 and the third material 300 may be any one of AlSb, InAlSb, AlAsSb, InAlAsSb, and GaSb. In another embodiment of the present invention, when the first material 100 is InAs/InAsSb, each of the second material 200 and the third material 300 is AlSb, InAlSb, AlAsSb, InAlAsSb, and GaAsSb. can be any one of

Specifically, the first material 100 and the second material 200 are selected as two semiconductor materials having a large difference in work function. When selecting, the selection is made based on the arrangement table of the lattice constant, work function, and band gap of each semiconductor material shown in FIG. 2 (b). For example, the selection of the first material 100 may include InAs, InSb, GaSb, InGaAs, InGaAsP, and mixtures thereof, and in one embodiment of the present invention, the first material 100 may be InAs. there is. In addition, the second material 200 may be selected from AlSb, AlAs, InGaSb, InGaAs, GaSb, and mixtures thereof, and a conduction band having higher energy than the conduction band of the first material 100. A material having a band and at the same time having a valence band higher than or equal to the valence band (valence band) of the first material 100 is selected. In one embodiment of the present invention, the second material 200 may be AlAsSb.

By forming the nBn structure through the step of forming the 1n absorption layer (S100), the step of forming the barrier layer (S200), and the step of forming the 2n absorption layer (S300), mid-infrared rays using the nBn structure The photodetection device 1 can be implemented.

Preferably, the mid-infrared photodetector 1 using the nBn structure includes a 1n absorbing layer formed of a first material 100 having a band gap of 0.9eV or less; The first material 100 and the second material 200 are mixed on the upper surface of the 1n absorption layer, but the ratio of the first material 100 decreases and the ratio of the second material 200 increases toward the upper side. A barrier layer formed in an increasing shape; and a 2n absorption layer formed of the first material 100 on the upper surface of the barrier layer.

The mid-infrared photodetector 1 using the nBn structure can be used as a photodetector operating in a mid-infrared wavelength band of 3 to 5 micrometers when a reverse bias is applied. In addition, the mid-infrared photodetector 1 according to an embodiment of the present invention can improve the signal-to-noise ratio (S/N ratio) by effectively suppressing dark current by the nBn structure including the barrier layer. .

Meanwhile, as the type of material forming the 1n absorbing layer and the 2n absorbing layer, InAs, InSb, GaSb, InGaAs, InGaAsP, and a mixture thereof may be selected, and InAs may be specifically exemplified. When InAs, InSb, GaSb, InGaAs, InGaAsP, and mixtures thereof are formed as the 1n absorption layer and the 2n absorption layer, types of materials capable of forming the barrier layer include AlSb, AlAs, InGaSb, InGaAs, GaSb and A mixture of these can be selected, a material having a conduction band of higher energy than the conduction band of the first material 100, and at the same time higher than the valence band of the first material 100 or Select materials with the same valence band. Specifically, AlAsSb can be exemplified.

4 conceptually illustrates an nBn structure according to an embodiment of the present invention.

The mid-infrared photodetector 1 according to an embodiment of the present invention may include the nBn structure shown in FIG. 4 . 4 is a mixture of the first material 100 and the second material 200 on the upper surface of the 1n absorption layer formed of the first material 100, but the ratio of the first material 100 toward the upper side. decreases and the ratio of the second material 200 includes the barrier layer formed in an increasing form, and the difference in lattice constant between the first material 100 and the second material 200 (within 0.2 Å) ) corresponds to an embodiment of the nBn structure in which the difference in valence band energy level is not considered.

In this case, at point I shown in FIG. 4, the ratio of the first material 100 is 100%, so the lattice constant of the first material 100 and the lattice constant corresponding to the valence band energy level and the valence band can have energy levels.

At point II shown in FIG. 4, the ratio of the second material 200 may be 100%, and the difference between the lattice constant and the first material 100 may have a lattice constant of 0.2 Å or less. 4 does not consider the difference between the valence band energy levels of the first material 100 and the second material 200, so that the valence band energy level of the second material 200 at point II and the A relatively large difference in the valence band energy level of the first material 100 may occur.

Preferably, the energy level of the conduction band of the first material 100 forming the 1n absorbing layer and the 2n absorbing layer is Point I The conduction band and valence band energy levels of the first material 100 forming the barrier layer correspond to the conduction band and valence band energy levels of the first material 100 forming the 1n absorption layer, respectively, At point II, the energy level of the conduction band of the second material 200 forming the barrier layer is higher than that of the conduction band of the first material 100 forming the 2n absorption layer, and at point II, the barrier layer The energy level of the valence band of the second material 200 formed is lower than that of the valence band of the first material 100 forming the 2n absorption layer. Also, the energy level of the conduction band of the second material 200 forming the barrier layer may increase from point I to point II, and the energy level of the valence band may decrease from point I to point II.

With this structure, when a reverse bias is applied to the mid-infrared photodetector 1, holes can freely move in the valence band, but electrons are restricted by the barrier layer, so dark current can be suppressed. .

5 conceptually illustrates an nBn structure according to an embodiment of the present invention.

The mid-infrared photodetector 1 according to an embodiment of the present invention may include the nBn structure shown in FIG. 5 . 5 is a mixture of the second material 200 and the third material 300 on the upper surface of the 1n absorption layer formed of the first material 100, but the ratio of the second material 200 toward the upper side. is reduced and the ratio of the third material 300 is increased, and the difference between the lattice constants of the first material 100 and the second material 200 is not considered. The difference in valence band energy levels (within 2.0 eV) is taken into account, and the difference in lattice constants (within 0.2 Å) between the first material 100 and the third material 300 is taken into account. corresponds to an embodiment of the nBn structure that is not considered.

In this case, at point I shown in FIG. 5, the ratio of the first material 100 is 100%, and at point II, the ratio of the second material 200 is 100%, so that the first material It may have a valence band energy level in which a difference between (100) and the valence band energy level is within 2.0 eV. At this time, at point II, the difference between the lattice constants of the first material 100 and the second material 200 is not considered, so the lattice constant of the second material 200 and the lattice constant of the first material 100 are not considered. A relatively large difference in constants may occur.

On the other hand, at point III, the difference between the lattice constants of the first material 100 and the third material 300 may have a lattice constant within 0.2 Å. At this time, at point III, the difference between the valence band energy level of the first material 100 and the third material 300 is not considered, and thus the valence band energy level of the third material 300 and the first material ( 100) may cause a relatively large difference in valence band energy level.

Preferably, the energy level of the conduction band of the first material 100 forming the 1n absorbing layer and the 2n absorbing layer is The energy level of the conduction band of the second material 200 forming the barrier layer is higher than the energy level of the valence band of the second material 200 forming the barrier layer and is higher than the energy level of the valence band of the second material 200 forming the barrier layer. The energy level of the conduction band of the third material 300 forming the layer is higher than the energy level of the valence band of the third material 300 forming the barrier layer, and the first material forming the barrier layer at point II. The energy level of the valence band of the second material 200 corresponds to the energy level of the valence band of the first material 100 forming the 1n absorption layer, but the conduction band of the second material 200 forming the barrier layer. The energy level of is higher than the energy level of the conduction band of the first material 100 forming the 1n absorption layer, and the energy level of the conduction band of the third material 300 forming the barrier layer at point III is the 2n Although higher than the energy level of the conduction band of the first material 100 forming the absorption layer, the energy level of the valence band of the third material 300 forming the barrier layer is the first material forming the 2n absorption layer ( 100) is lower than the valence band energy level. In addition, the energy level of the conduction band of the second material 200 and the third material 300 forming the barrier layer is maintained or increased from point II to point III, and the energy level of the valence band is maintained at point II. It may decrease towards point III.

With this structure, when a reverse bias is applied to the mid-infrared photodetector 1, holes can freely move in the valence band, but electrons are restricted by the barrier layer, so dark current can be suppressed. . In addition, it is possible to relatively broaden the range for selecting materials for realizing the nBn structure.

6 schematically shows equipment for performing a molecular beam epitaxy process according to an embodiment of the present invention.

The equipment corresponds to molecular beam epitaxy (MBE) equipment, and may perform a molecular beam epitaxy process in which a thin film is grown by colliding atomic or molecular beams on a substrate in a high vacuum chamber. As shown in FIG. 6 , the equipment may include an effusion cell that accommodates the material of the thin film grown on the substrate therein. In addition, the equipment may operate a heater in a part of the e-fusion cell to heat a material accommodated in the e-fusion cell or operate while controlling a shutter of the e-fusion cell.

In one embodiment of the present invention, the mid-infrared photodetector 1 using the nBn structure can be manufactured by a molecular beam epitaxy process. In addition, in one embodiment of the present invention, the equipment includes a first e-fusion cell accommodating therein the first material 100 forming the 1n absorbing layer and the 2n absorbing layer; and a second e-fusion cell accommodating the second material 200 forming the barrier layer therein, wherein shutters or heaters of the first e-fusion cell and the second e-fusion cell operate. may be controlled to form the 1n absorbing layer, the barrier layer, and the 2n absorbing layer.

Meanwhile, in another embodiment of the present invention, the equipment includes a first e-fusion cell accommodating therein the first material 100 forming the 1n absorbing layer and the 2n absorbing layer; a second e-fusion cell accommodating therein the second material 200 forming the barrier layer; and a third e-fusion cell accommodating therein the third material 300 forming the barrier layer, wherein the first e-fusion cell, the second e-fusion cell, and the third e-fusion cell are The 1n absorbing layer, the barrier layer, and the 2n absorbing layer may be formed by controlling the operation of a shutter or a heater of the fusion cell.

7 schematically illustrates a relationship between time and heater temperature of a first e-fusion cell and a second e-fusion cell according to an embodiment of the present invention.

In the forming of the barrier layer (S200) according to an embodiment of the present invention, the first e-fusion cell in which the first material 100 is accommodated and the second material 200 are formed by using a molecular beam epitaxy process. ) is accommodated, in a state in which the shutters of each of the second e-fusion cells are fully opened, the heater temperature of the first e-fusion cell decreases or is maintained, and the heater temperature of the second e-fusion cell increases as it goes upward. To form the barrier layer.

As described above, in one embodiment of the present invention, the 1n absorbing layer, the barrier layer, and the 2n absorbing layer are formed by controlling the operation of shutters or heaters of the first e-fusion cell and the second e-fusion cell. can do. FIG. 7 shows the heaters of the first e-fusion cell and the second e-fusion cell in a state in which the shutters of the first e-fusion cell and the shutters of the second e-fusion cell are fully opened in the step of forming the barrier layer. Corresponds to an embodiment that controls the operation of.

That is, in an embodiment of the present invention, in a state in which the shutters of the first e-fusion cell and the second e-fusion cell are fully opened, the temperature of the heater of the first e-fusion cell is reduced, and the temperature of the second e-fusion cell is reduced. By increasing the heater temperature, the ratio of the first material 100 accommodated in the first e-fusion cell decreases toward the upper side, and the ratio of the second material 200 accommodated in the second e-fusion cell decreases. The barrier layer may be formed in an increasing ratio.

Meanwhile, in another embodiment of the present invention, by controlling the operation of shutters or heaters of the first e-fusion cell, the second e-fusion cell, and the third e-fusion cell, and the 2n absorption layer.

Preferably, in the step of forming the barrier layer (S200), the second e-fusion cell in which the second material 200 is accommodated and the third material 300 are accommodated using a molecular beam epitaxy process. In a state in which the shutters of each of the third e-fusion cells are completely open, the barrier layer is formed in such a way that the heater temperature of the second e-fusion cell decreases and the heater temperature of the third e-fusion cell increases as it goes upward. can do. That is, in a state in which the shutters of the first e-fusion cell, the second e-fusion cell, and the third e-fusion cell are fully opened, the temperature of the heater of the second e-fusion cell is reduced, and the temperature of the third e-fusion cell is reduced. By increasing the heater temperature, the ratio of the second material 200 accommodated in the second e-fusion cell decreases toward the upper side, and the ratio of the third material 300 accommodated in the third e-fusion cell decreases. The barrier layer may be formed in an increasing ratio.

By forming the barrier layer in this way, the barrier layer can be matched with the 1n absorbing layer and the 2n absorbing layer even without considering both the lattice constant and the valence band energy level, and accordingly, for realizing the nBn structure It is possible to further expand the range in which materials can be selected.

8 schematically illustrates a relationship between time and shutter aperture ratio of a first e-fusion cell and a second e-fusion cell according to an embodiment of the present invention.

In the forming of the barrier layer (S200) according to an embodiment of the present invention, the first e-fusion cell in which the first material 100 is accommodated and the second material 200 are formed by using a molecular beam epitaxy process. ) is accommodated, in a state where the heater temperature of each of the second e-fusion cells is set to a preset temperature, the aperture ratio of the shutter of the first e-fusion cell decreases toward the upper side, and the aperture ratio of the shutter of the second e-fusion cell decreases. may form the barrier layer in an increasing form.

At this time, the aperture ratio of the shutter may adjust the area of the aperture, and the effective aperture ratio of the shutter, that is, the duty ratio, which is the ratio between the open time and the closed time within a certain number of shutter changes, may be changed.

As described above, in one embodiment of the present invention, the 1n absorbing layer, the barrier layer, and the 2n absorbing layer are formed by controlling the operation of shutters or heaters of the first e-fusion cell and the second e-fusion cell. can do. FIG. 8 shows the operation of the shutters of the first e-fusion cell and the second e-fusion cell in a state where the heater temperature of the first e-fusion cell and the heater temperature of the second e-fusion cell are set to preset temperatures. Corresponds to the controlling embodiment.

That is, in an embodiment of the present invention, in a state in which heater temperatures of the first e-fusion cell and the second e-fusion cell are set to preset temperatures, the aperture ratio of the shutter of the first e-fusion cell is reduced, and the By increasing the aperture ratio of the shutter of the 2 e-fusion cell, the ratio of the first material 100 accommodated inside the first e-fusion cell decreases toward the upper side, and the ratio of the first material 100 accommodated inside the second e-fusion cell decreases. The barrier layer may be formed in a form in which the ratio of the two materials 200 increases.

Meanwhile, in another embodiment of the present invention, by controlling the operation of shutters or heaters of the first e-fusion cell, the second e-fusion cell, and the third e-fusion cell, and the 2n absorption layer. At this time, the aperture ratio of the shutter may adjust the area of the aperture, and the effective aperture ratio of the shutter, that is, the duty ratio, which is the ratio between the open time and the closed time within a certain number of shutter changes, may be changed.

Preferably, in the step of forming the barrier layer (S200), the second e-fusion cell in which the second material 200 is accommodated and the third material 300 are accommodated using a molecular beam epitaxy process. In a state in which the heater temperature of each of the 3rd e-fusion cells is set to a preset temperature, the aperture ratio of the shutter of the 2nd e-fusion cell decreases toward the upper side, and the aperture ratio of the shutter of the 3rd e-fusion cell increases. To form the barrier layer. That is, in a state where the heater temperatures of the first e-fusion cell, the second e-fusion cell, and the third e-fusion cell are set to a predetermined temperature, the aperture ratio of the shutter of the second e-fusion cell is reduced, and the 3 By increasing the aperture ratio of the shutter of the e-fusion cell, the ratio of the second material 200 accommodated inside the second e-fusion cell decreases toward the upper side, and the ratio of the second material 200 accommodated inside the third e-fusion cell decreases. The barrier layer may be formed in a form in which the ratio of the three materials 300 increases.

By forming the barrier layer in this way, the barrier layer can be matched with the 1n absorbing layer and the 2n absorbing layer even without considering both the lattice constant and the valence band energy level, and accordingly, for realizing the nBn structure It is possible to further expand the range in which materials can be selected.

According to an embodiment of the present invention, by implementing the nBn structure using more diverse materials, it is possible to realize an effect capable of implementing a mid-infrared photodetector suitable for commercialization while having excellent detection performance.

According to an embodiment of the present invention, by forming the barrier layer in a special way, the barrier layer can be matched with the n-absorption layer even without considering both the lattice constant and the valence band energy level, and the material forming the n-absorption layer and the barrier layer It can exert the effect of expanding the degree of freedom of selection for .

According to an embodiment of the present invention, it is possible to achieve an effect of improving a signal-to-noise ratio by suppressing dark current by the nBn structure including the barrier layer.

As described above, although the embodiments have been described with limited examples and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by an equivalent, appropriate results can be achieved. Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

1: mid-infrared photodetector
S100: Forming a 1n absorbing layer
100: first material
S200: Forming a barrier layer
200: second material 300: third material
S300: Forming a 2n Absorption Layer

Claims (13)

A method for manufacturing a mid-infrared photodetector using an nBn structure,
Forming a 1n absorbing layer of a first material having a band gap of 0.9 eV or less;
mixing the first material and the second material on the upper surface of the 1n absorption layer, forming a barrier layer in such a manner that a ratio of the first material decreases and a ratio of the second material increases toward the upper side; and
Forming a 2n absorbing layer of the first material on the upper surface of the barrier layer; manufacturing method of a mid-infrared photodetector including a.
The method of claim 1,
A difference between the lattice constant of the second material and the lattice constant of the first material is within 0.2 Å.
The method of claim 1,
The method of manufacturing a mid-infrared photodetector, wherein the energy level of the conduction band of the second material is higher than the energy level of the valence band of the second material.
The method of claim 1,
When the first material is InAs, the second material is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb,
When the first material is InAsSb, the second material is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb,
When the first material is InSb, the second material is any one of AlSb, InAlSb, AlAsSb, InAlAsSb, and GaAsSb.
The method of claim 1,
Forming the barrier layer,
In a state in which the shutters of the first e-fusion cell accommodating the first material and the second e-fusion cell accommodating the second material are completely open using the molecular beam epitaxy process, the first e-fusion cell is moved upward toward the upper side. The method of manufacturing a mid-infrared photodetection device, wherein the barrier layer is formed in such a manner that a heater temperature of the fusion cell is reduced or maintained, and a heater temperature of the second e-fusion cell is increased.
The method of claim 1,
Forming the barrier layer,
Using the molecular beam epitaxy process, in a state in which the heater temperature of each of the first e-fusion cell accommodating the first material and the second e-fusion cell accommodating the second material is set to a predetermined temperature, the temperature increases toward the upper side. wherein the barrier layer is formed in such a manner that the aperture ratio of the shutter of the first e-fusion cell decreases and the aperture ratio of the shutter of the second e-fusion cell increases.
A method for manufacturing a mid-infrared photodetector using an nBn structure,
Forming a 1n absorbing layer of a first material having a band gap of 0.9 eV or less;
mixing a second material and a third material on an upper surface of the 1n absorption layer, forming a barrier layer in such a manner that a ratio of the second material decreases and a ratio of the third material increases toward the top; and
Forming a 2n absorbing layer of the first material on the upper surface of the barrier layer; manufacturing method of a mid-infrared photodetector including a.
The method of claim 7,
The method of manufacturing a mid-infrared photodetector, wherein the difference between the energy level of the valence band of the second material and the energy level of the valence band of the first material is within 2.0 eV.
The method of claim 7,
A difference between the lattice constant of the third material and the lattice constant of the first material is within 0.2 Å.
The method of claim 7,
The energy level of the conduction band of the second material is higher than the energy level of the valence band of the second material;
The energy level of the conduction band of the third material is higher than the energy level of the valence band of the third material, and the manufacturing method of the mid-infrared photodetector.
The method of claim 7,
When the first material is InAs, each of the second material and the third material is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb,
When the first material is InAsSb, each of the second material and the third material is any one of AlSb, InAlSb, AlAsSb, and InAlAsSb,
When the first material is InSb, each of the second material and the third material is any one of AlSb, InAlSb, AlAsSb, InAlAsSb, and GaSb.
The method of claim 7,
Forming the barrier layer,
In a state in which the shutters of the second e-fusion cell accommodating the second material and the third e-fusion cell accommodating the third material are fully open using the molecular beam epitaxy process, the second e-fusion cell is moved upward. The method of claim 1 , wherein the barrier layer is formed in such a manner that a heater temperature of the fusion cell decreases and a heater temperature of the third e-fusion cell increases.
The method of claim 7,
Forming the barrier layer,
Using the molecular beam epitaxy process, in a state in which the heater temperature of each of the second e-fusion cell accommodating the second material and the third e-fusion cell accommodating the third material is set to a predetermined temperature, the temperature increases toward the upper side. wherein the barrier layer is formed in such a manner that an aperture ratio of a shutter of the second e-fusion cell decreases and an aperture ratio of a shutter of the third e-fusion cell increases.

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