KR101996407B1 - A semiconductor stack having the characteristics of interlayer orientation-dependent light absorption and emission - Google Patents

Abstract

The present invention discloses a method of analyzing a semiconductor stack having interlayer orientation-based light absorption and light emission characteristics. The method comprises the steps of: (a) preparing a first stack of transition metal-chalcogen compounds with a matching crystal orientation using chemical vapor deposition; (b) producing a second stack of transition metal-chalcogen compounds wherein the crystal orientation is discordant by controlling the angle of rotation using physical transfer; (c) measuring an absorption and emission pattern of light between the atomic layers of each of the first and second stacks; And (d) dynamically analyzing the absorption and emission patterns of the measured light to determine a transition band gap. According to the present invention, it is possible to selectively adjust or dislocate the relative crystal orientation of the two-dimensional semiconductor laminated structure, thereby forming a new electronic structure artificially, and a new artificial low dimensional semiconductor structure . In addition, interaction between two-dimensional atomic layer materials is newly determined according to the angle of rotation between atomic layers, and various photophysical phenomenon researches become possible. Through the control of material properties through this, two-dimensional material luminous body, laser, It is possible to apply it to a wide range of applications.

Description

[0001] The present invention relates to a semiconductor stack having interlayer orientation-based optical absorption and emission characteristics,

The present invention relates to a method of analyzing semiconductor stacks, and more particularly, to a method of preparing a stack of transition metal-chalcogenide compounds by controlling the angle of rotation using chemical vapor deposition and physical transfer, The present invention relates to a method of analyzing a semiconductor stack having interlayer orientation-based light absorption and luminescence characteristics capable of discriminating a transition band gap by measurement and kinetic analysis.

Transition metal-chalcogenide layered compounds, which are currently attracting attention from the scientific community as a next-generation two-dimensional semiconductor material to replace silicon semiconductors, are known as the thinnest high-performance semiconductors that exist even at a single atomic layer thickness.

This compound can absorb and emit visible light as well as excellent electronic device characteristics and is expected to be widely applied to high performance electronic / optical / photoelectric devices.

Particularly, in the case of molybdenum (Mo), which is one of the transition metals, or molybdenum disulfide (MoS ₂ ) and tungsten disulfide (WS ₂ ), which are compounds of tungsten (W) and sulfur, However, since it has the physical properties of semiconductors, it has attracted much attention as a next generation two-dimensional semiconductor material to replace the existing graphene.

That is, in the case of molybdenum disulfide (MoS ₂ ) and tungsten disulfide (WS ₂ ) composed of a single atom layer, a direct transition band gap characteristic is exhibited due to the change of the electronic structure, and even though the thickness of the nanometer is 10% And thus it is possible to widely apply to high performance electronic and photoelectric devices.

In the case of heterogeneous structures formed by stacking and bonding two - dimensional single atomic layer materials, it is expected that new electrical and optical characteristics will be exhibited due to interlayer interactions occurring at the interface.

In the hetero-layer structure formed by vertically stacking the different single-layer two-dimensional semiconductors, interlayer interactions are strongly generated, and interlayer excitons are generated when light is incident. Therefore, the band gap The light absorption and the luminescence characteristics in the energy band different from that of the light absorption layer are observed by the theoretical physicists.

However, in the past, a laminate structure was implemented by separating each single-layer material by a mechanical peeling method and stacking it using physical transfer.

However, in the case of the laminated structure formed in this way, since the relative crystal orientations of the respective single layers are inconsistent, a process capable of realizing a laminated structure in which the crystal directions of the two atomic layers coincide with each other is required for strong interlayer interaction, It is indispensable to develop an optical measurement technique capable of effectively observing the interaction of the light source.

Therefore, the present inventors have succeeded in producing a compound having a crystal orientation inconsistency by using a chemical vapor deposition method and a two-dimensional vertical laminated semiconductor compound whose rotational angle and crystal direction are exactly the same and physical transfer, The absorption and emission of light can be adjusted to an indirect transition gap directly in the transition gap, and the application to a new type of two-dimensional light emitter has been developed.

It is an object of the present invention to provide a two-dimensional superlattice structure of a single-atom-layer semiconductor in which the optical properties of the two-dimensional superlattice structure are controlled by controlling the rotation direction of interatomic crystals to control the absorption and emission characteristics of a new wavelength due to inter- The present invention provides a method of analyzing a semiconductor stack having interlayer orientation-based light absorption and luminescence characteristics, which synthesizes a superlattice structure in which the relative crystal orientations of chalcogen compounds coincide with each other.

The problem to be solved by the present invention is not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be clearly understood by a person skilled in the art from the following description.

In order to accomplish the above object, the present invention provides a method of analyzing a semiconductor stack having light absorption and emission characteristics based on interlayer alignment, comprising: (a) forming a first stack of transition metal-chalcogen compounds having a crystal orientation matching by chemical vapor deposition A step to be produced; (b) producing a second stack of transition metal-chalcogen compounds wherein the crystal orientation is discordant by controlling the angle of rotation using physical transfer; (c) measuring an absorption and emission pattern of light between the atomic layers of each of the first and second stacks; And (d) dynamically analyzing the absorption and emission patterns of the measured light to determine a transition band gap.

The details of other embodiments are included in the detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and / or features of the present invention and the manner of achieving them will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. And is provided to fully explain the scope of the present invention to those skilled in the art.

According to the present invention, it is possible to selectively adjust or dislocate the relative crystal orientation of the two-dimensional semiconductor laminated structure, thereby forming a new electronic structure artificially, and a new artificial low dimensional semiconductor structure .

In addition, interaction between two-dimensional atomic layer materials is newly determined according to the angle of rotation between atomic layers, and various photophysical phenomenon researches become possible. Through the control of material properties through this, two-dimensional material luminous body, laser, It is possible to apply it to a wide range of applications.

FIG. 1 is a flowchart showing a method of analyzing a semiconductor stack having interlayer alignment-based light absorption and light emission characteristics according to the present invention.
FIG. 2 is a flowchart showing a first and a second stack manufacturing method (S100 and S300) for implementing the analyzing method of the present invention shown in FIG.
3 is a view illustrating a process of forming the first and second stacks in a heterogeneous vertical lamination structure according to the manufacturing method shown in FIG.
4 is a view showing a process in which the semiconductor stack of the present invention shown in FIG. 1 absorbs and emits light according to rotation of a single-layer hexagonal semiconductor.
FIG. 5 is a view showing a rotation crystal structure and absorption and emission characteristics of a MoS ₂ / WS ₂ stack which is a semiconductor stack of the present invention manufactured according to the manufacturing method shown in FIG.
Figure 6 is a diagram showing the excitonic dynamics of a very fast time analyzed conformed stack or random stacked double stack of the present invention.
7 is a diagram showing a band structure of the conformal laminate or random lamination of the MoS ₂ / WS ₂ double layer of the present invention and a partial charge density plot of the MoS ₂ / WS ₂ double layer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor can properly define the concept of the term to describe its invention in the best way Should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention.

In the specification, when a component is referred to as being "comprising" or "including" an element, it is to be understood that this may include other elements, . Also, the terms "module", "apparatus", "step", and the like described in the specification mean a unit for processing at least one function or operation, and may be implemented by hardware or software or a combination of hardware and software.

Hereinafter, for convenience, the molybdenum disulfide, which is the first transition metal-chalcogen compound, is referred to as "MoS ₂ " and the tungsten disulfide as the second transition metal-chalcogen compound is referred to as "WS ₂ ".

FIG. 1 is a flowchart showing a method of analyzing a semiconductor stack having interlayer alignment-based light absorption and light emission characteristics according to the present invention.

A first stack of vertical structures of transition metal-chalcogen compounds with crystal orientation matching is prepared using chemical vapor deposition (S100).

A second stack of the vertical structure of the transition metal-chalcogen compound in which crystal orientation is inconsistent by controlling the rotation angle using physical transfer is prepared (S200).

At this time, physical transfer is an imprint method in which a material is transferred to a substrate by a stamp, and the surface energy between the material and the substrate surface is controlled by a physical treatment method.

The absorption and emission patterns of the inter-atomic layer light of each of the first and second stacks are measured (S300).

The transition band gap is determined by dynamically analyzing the absorption and emission patterns of the measured light (S400).

FIG. 2 is a flowchart showing a first and a second stack manufacturing method (S100, S200) for implementing the analyzing method of the present invention shown in FIG.

3 is a view illustrating a process of forming the first and second stacks in a heterogeneous vertical lamination structure according to the manufacturing method shown in FIG.

Single atomic layer MoS ₂ (Molybdenum Disulfide, disulfide, molybdenum), WS ₂ have the (Tungsten Disulfide, tungsten disulfide) is several tens of micrometers, the triangular shaped single crystal having a width different crystal each direction SiO ₂ (300nm) / And spontaneously grows up to several tens of microns in the horizontal direction on the Si substrate (S110).

At this time, the single atomic layer MoS ₂ is composed of MoO ₃ (molybdenum trioxide) and sulfur (S) as precursors in the form of solid powder, WS ₂ is tungsten trioxide (WO ₃ ) And sulfur (S) as precursors by chemical vapor deposition in a 12-inch diameter hot-wall quartz-tube.

Within the triangular planes scattered on the substrate, the individual oriented single layer crystals are incorporated into a larger single layer crystal over several millimeters (S120).

MoS _{2 ->} WS ₂ , The first grown single atomic layer MoS ₂ Lt; RTI ID = 0.0 > WS ₂ (S130).

Then, heteroepitaxial vertical stacking growth is performed by a sequential second single-layer crystallization by a transition precursor at a predetermined temperature (S140, S150), as shown in FIG. 3A.

As shown in Figures 3C-3E, the MOS at 660 < RTI ID = 0.0 > ₂  Single layer growth at 800 ° C WS ₂  Preceded by monolayer growth.

The second monolayer is nucleated at the lateral edge of the first monolayer and the MOS ₂  Grown in a vertical direction on a single layer (S160).

At this time, a single atomic layer MoS ₂  The triangle WS ₂  (S170), the single-crystal single crystal is joined to the WS ₂  Thereby forming a single atomic layer thin film (S180).

Through such a synthesis process, a monolayer molybdenum disulfide (MoS ₂ ) / Tungsten disulfide (WS ₂ A first stack, which is a vertical stacked structure, is manufactured (S100), and a second stack in which crystal directions are inconsistent is manufactured using physical transfer (S200, S300).

At this time, high-resolution transmission electron microscopy (HRTEM) confirms the coincidence of the relative crystal orientation.

In addition, the luminescence and absorption characteristics of the two types of compounds are analyzed through a detailed process described below (S400), and a kinetic analysis (S500) with picosecond resolution It is found that when the angles are exactly matched, they have a direct transition bandgap (S600).

4 is a view showing a process in which the semiconductor stack of the present invention shown in FIG. 1 absorbs and emits light according to rotation of a single-layer hexagonal semiconductor.

4A shows a case in which the vertical stacks of WS ₂ and MOS ₂ are in the momentum (K) space, that is, in the reciprocal lattice structure, and FIG. 4B shows the case in which the vertical stacks of WS ₂ and MOS ₂ are in the actual space, .

As shown in FIG. 4A, the vertical stacking structure of two-dimensional MoS ₂ and WS _{2 in} the form of a single atomic layer grown using a spatial spectrum and a time-resolved photoelectron probe, and absorption and emission As a result of the experiment, it was found that when the single atomic layers MoS ₂ and WS ₂ are expressed in a hexagonal shape in the left-handed inverted lattice structure and light having a predetermined energy is emitted when the rotation angle is "0" (Marked with a pink arrow).

In the reverse lattice structure on the right side, it was observed that no light was emitted (indicated by black arrows) when lamination was performed at an arbitrary rotation angle.

In this case, as shown in FIG. 4B, the vertical stacked structure of the two-dimensional MoS ₂ and WS ₂ has a hexagonal hexagonal unit cell stack of the MoS ₂ and WS ₂ single layers without matching interlayer rotation, It was formed by heterogeneous growth.

The two monolayer crystals have the same hexagonal crystal symmetry and similar size (a = 3.150 A for MoS ₂ and a = 3.153 A for WS ₂ , where a is the length of one side of the unit cell).

Thus, the individual atoms are located so that the single layer crystal laminating order can be thermodynamically stable without rotational misalignment.

FIG. 5 is a view showing a rotation crystal structure and absorption and emission characteristics of a MoS ₂ / WS ₂ stack which is a semiconductor stack of the present invention manufactured according to the manufacturing method shown in FIG.

FIG. 5A is a planar transmission electron microscope image of a vertical stack, and the bottom insertion represents a fast Fourier transform diffraction pattern in each region, which does not change in the stack.

Figures 5b and 5c are optical microscope images of the MoS ₂ / WS ₂ stacking device and the growth of local light absorption and luminescence; Figures 5d to 5f show the photocurrent ( _Iph ) and MoS ₂ (blue), WS ₂ (Green), and FIG. 5g and FIG. 5h are comparisons of the photocurrent (I _ph ) and the emission spectrum (PL) spectra of the MoS ₂ / WS ₂ bilayer .

In order to investigate the absorption / luminescence patterns of the MoS ₂ / WS ₂ laminated structure, a device capable of measuring electrical current by placing electrical contacts on a laminated structure whose rotation angle is controlled to "0" by chemical vapor deposition has been manufactured.

The current is then measured while focusing the light locally to ascertain the mode of absorption of the photocurrent.

Further, the spectrum of the light emitted while the light having the energy larger than the bandgap of the two-dimensional structure is analyzed, and the emission pattern is confirmed by comparing with the absorption pattern.

That is, as shown in FIG. 5 (a), it can be seen that by edge nucleation, heterogeneous stack growth occurs through the second WS ₂ monolayer on the first MoS ₂ and WS ₂ monolayers, It is confirmed that the fast Fourier transform has the same plane direction of the time unit cell.

Thus, the bilayer stack was rotationally matched through the van der Waals interface, confirming that the angle of rotation was "0 ".

At this time, the arbitrary double layer stack is made by manually stacking the individual MoS ₂ and WS ₂ single layers, so that the order of rotation misalignment is unknown.

5b and 5c, the electrical contacts W1, W2, M1 and M2 are formed on the MoS ₂ / WS ₂ laminated structure obtained by the chemical vapor deposition method to focus the light locally, , Iph), light absorption and emission due to intra-ML and inter-ML transitions were confirmed.

At this time, the diffraction limited laser beam spot must be small enough to spatially analyze each single layer in the bilayer stack.

Also, partial illumination is used for the collection of photocurrent spectra, since direct probing of the optical absorption of individual single layers without an ensemble average is technically difficult due to the small light absorption of the single layer crystal.

As shown in FIG. 5D, it can be seen that the photoelectrons indicated by the solid line start to absorb at 1.8 eV or more, resonance occurs at the points A and B, and the luminous characteristics indicated by the hollow circle are You can see that it is a lot.

This absorption and emission pattern is identical to that found in the MoS ₂ single atom layer structure.

As shown in FIG. 5E, it can be seen that resonance occurs at points A and B as in the case of the MoS ₂ single atom layer structure in the WS ₂ single atom layer structure, but the resonance interval is larger than that of the MoS ₂ single atom layer structure .

As shown in FIG. 5F, in the case of the MoS ₂ / WS ₂ vertical stacked structure having the rotation angle of "0", the emission spectrum appears near 1.5 eV unlike the case of the single atomic layer.

As shown in FIG. 5G, it can be seen that the light absorption pattern of MoS ₂ / WS ₂ (light green) as a vertically stacked structure is leftward shifted compared with MoS ₂ (blue) and WS ₂ (red) have.

As shown in FIG. 5 (h), in the case of MoS ₂ / WS ₂ (green) in which the light emission pattern is vertical stacking structure, the spectrum appears near 1.5 eV, and the vertical Structure (yellow), the emission spectrum is not observed near 1.5 eV.

Figure 6 is a diagram showing the excitonic dynamics of a very fast time analyzed conformed stack or random stacked double stack of the present invention.

The top panel of FIG. 6A is a transient dynamics comparison of the interlayer excitons of the coincidentally stacked bilayer and the optionally stacked bilayers, and the two bilayers were pumped by the same laser dose and measured at the same probe photon energy of 1.6 eV.

In addition, the bottom panel of Fig. 6a shows the interlayer exciton dynamics of MoS ₂ (blue, 1.87 eV) and WS ₂ (red, 1.96 eV) measured in a double layer deposited in the same laser pumped dose.

Figure 6b is a dose-dependent pump of the double-layer laminated in correspondence indicates the maximum T / T _0, Figure 6c is a spectral analysis on the direct inter-exciton state up to 1.6 eV T / T ₀ is shown.

Figure 6d is the pump-probe delay ΔT as a function of (from left to right), the pump-a schematic diagram of the induction exciton transition, after pump here (on the left) of 3.1 eV is immediately electron is rapidly transferred to the MoS _2, fast hole WS ₂ (center), and then interlayer recombination is measured by setting the probe photon energy of 1.6 eV (right).

In order to compare the observed results in the interlayer transitions of more consistent and consistently stacked bilayers and randomly stacked bilayers, ultrafast time-resolved optical pump probe spectroscopy on single interlayer transition dynamics is used.

That is, FIG. 6 shows a pump-probe experiment to observe the carrier dynamics associated with interlayer emission near the 1.5 eV emission pattern in the vertical stacked structure of MoS ₂ / WS _2. This is a graphical representation of the results.

Here, in order to perform an experiment having a resolution of picoseconds, a pump probe test is performed in such a manner that a pump light having a pulse width of several tens of femtoseconds is incident on a material, and after a predetermined time (t) It is an experiment to re-enter the material and see the change of transmission.

When a pump light having energy of 3.1 eV is incident on a vertical stacked structure, electrons and holes are generated, and the electrons and holes are separated from each other by charge separation and recombination. By confirming the time of the processes, it is possible to directly confirm the interlaminar absorption and the photoluminescence dynamics of the vertical stacked structure.

As shown in FIG. 6A, it can be seen that the yellow graph is interlayer recombination at a very high speed as a result of the coherent vertical lamination structure with the rotation angle of "0 & As a result of the laminated structure, it can be confirmed that the recombination occurs at a slower rate than the conformable vertical stacked structure.

That is, the laminated are 50-FS, is excited by the pump pulse of 3.1 eV, and 1.47 to 2.13 eV probe proton appropriate differential transmission data of energy (T / T _0, wherein T is a pump-induced transmission change, T ₀ is Pumping transmission) is measured as a function of the pump probe delay t.

As can be seen in the top graph of FIG. 6A, immediately after pumping both the conformal and random stacks, the signal for interlayer excitons with a 1.6 eV probe increases rapidly to T / T ₀ .

6b, the primary population dynamics dominate the emission (PL) and corresponding differential transmission data (T / T ₀ ) dynamics basically by showing that the signal increases linearly with the power of the light, It can be confirmed that it is not nonlinear.

As shown in FIG. 6C, it can be confirmed that the interlayer optical absorption occurs by resonance at 1.6 eV through comparison of the signal intensity according to the probe energy.

That is, the vertical structure has a new direct transition band gap of 1.6 eV.

As shown in Figure 6d, the photoexcited electrons and holes are immediately transferred to the preferred energy states of MoS ₂ and WS ₂ , and this rapid charge transfer and interlayer excitation distribution results in the measured emission intensities shown in Figures 5f and 5h .

If the charge transfer is slow compared to the individual interlayer excursion lifetime, no interlayer luminescence can be expected.

Thus, it can be seen from the result of the rapid recombination that the coherent vertical lamination structure having a rotation angle of "0 " has a direct transition band gap near 1.6 eV.

Figure 7 is the angle of rotation "through a drawing showing partial charge density plot of the present invention of MoS ₂ / WS of the _second double layer of correspondence laminated or randomness laminated band structure and the MoS ₂ / WS ₂ double layer, the theoretical approach and calculate 0 "and the electronic structure in the case of " 0 "

Figure 7a is MoS ₂ / WS, and the band structure of a _two-layer correspondence laminate of Figure 7b is a band structure of MoS ₂ / WS ₂ Double Layer 2 The 21.79 degree rotation as between the single-layer randomness laminate of Figure 7c is MoS ₂ / WS < / _{RTI >} double layer, with the top views showing the overlap of the native cell Brillouin region for each stack.

The dotted lines on the Brillouin region represent the path K calculated according to the band structure, and the conformable laminated bilayer with the rotation angle of "0 " has the direct-bandgap characteristic and the non- Shows an indirect-band gap characteristic.

In addition, the respective contributions of a single layer of MoS _{2 and} a single layer of WS ₂ are indicated by the size of the blue cross and the red circle, respectively.

Figures 7d-f are partial charge density plots of the structures used in Figures 7a-7c at the Γ point of the Valence band, where interlayer orbital interactions are identified from the charge density plots of the orbits at point G do. That is, the recombination of the charges associated with the band structure is related to the interlayer interaction.

Therefore, the superlattice structure of the present invention was firstly found to have a direct transition band gap, unlike the lamination structure through a simple physical transfer method having an indirect transition band gap in terms of light absorption and light emission. It is scientifically proved that the crystal rotation angle in the atomic layer semiconductor lamination structure describes the interaction between the atomic layers, suggesting that the fabrication of artificial semiconductor materials will become possible in the future.

That is, in the MoS ₂ / WS ₂ vertical heterogeneous bonding material, a new optical characteristic which is not possessed by a single layer, which is a constituent material, is expressed. This is due to the change of the electron band structure due to the interlayer interaction, As a result of studying the luminescent properties, the characteristics were observed as direct shear deformations originating from optoelectronic excitation between materials.

In the case of MoS ₂ / WS ₂ vertical heteromaterials synthesized by epitaxial structure, there is no rotational misfit between monomolecular layers. Therefore, there is no rotational mismatch in the momentum space, that is, the reciprocal lattice structure. It was first identified.

As described above, the method of analyzing a semiconductor stack having interlayer alignment-based light absorption and luminescence characteristics according to the present invention is characterized in that optical characteristics appearing in a two-dimensional superlattice structure of a single atom layer semiconductor control atomic layer crystal rotation direction, Analysis of Semiconductor Stack with Interlayer Orientation-Based Optical Absorption and Luminescence Characteristics for Synthesizing Superlattice Structure with Relative Crystallographic Directions of Two Transition Metal-Chalcogen Compounds to Control the Absorption and Luminescence Properties of New Wavelength .

Accordingly, the relative crystal orientation of the two-dimensional semiconductor laminated structure can be selectively matched or discordant, and a new electronic structure can be artificially formed, and a novel artificial low dimensional semiconductor structure do.

In addition, interaction between two-dimensional atomic layer materials is newly determined according to the angle of rotation between atomic layers, and various photophysical phenomenon researches become possible. Through the control of material properties through this, two-dimensional material luminous body, laser, It is possible to apply it to a wide range of applications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

(a) preparing a first stack of transition metal-chalcogen compounds with a single atomic layer rotation angle of "0 " with a crystal orientation consistent using chemical vapor deposition;
(b) preparing a second stack of transition metal-chalcogenide compounds whose crystal orientation is inconsistent by adjusting the rotation angle using physical transfer so that the interatomic rotation angle is not "0 ";
(c) measuring an absorption and emission pattern of light between the atomic layers of each of the first and second stacks; And
(d) dynamically analyzing the absorption and emission patterns of the measured light to determine a transition band gap;
Wherein the semiconductor stack has an interlayer orientation-based light absorption and light emission characteristics.
The method according to claim 1,
The step (a)
Wherein said single atomic layer of a first transition metal-chalcogen compound is grown on a silicon oxide substrate at a first temperature;
Wherein said single atomic layer of a second transition metal-chalcogen compound is incorporated onto said first transition metal-chalcogen compound to form a nucleus of said second transition metal-chalcogen compound from the edge of said first transition metal- The generation of which starts;
Wherein the second vertical metal-chalcogen compound is grown in a vertical direction on the first transition metal-chalcogenide compound by sequential single layer crystallization at a second temperature; And
The first transition metal-chalcogenide single crystal grown in the vertical direction is combined to form a single atomic layer thin film of a polycrystal, thereby forming the first stack having the same crystal orientation;
Wherein the semiconductor stack has an interlayer orientation-based light absorption and light emission characteristics.
The method according to claim 1,
The step (b)
Wherein said single atomic layer of a first transition metal-chalcogen compound is grown on a silicon oxide substrate at a first temperature;
Wherein said single atomic layer of a second transition metal-chalcogen compound is incorporated onto said first transition metal-chalcogen compound to form a nucleus of said second transition metal-chalcogen compound from the edge of said first transition metal- The generation of which starts;
Wherein the second vertical metal-chalcogen compound is grown in a vertical direction on the first transition metal-chalcogenide compound by sequential single layer crystallization at a second temperature; And
Wherein the first transition metal-chalcogen compound grown in the vertical direction is combined with a chemical reaction to form a mono-atomic layer thin film of polycrystalline to physically treat the surface energy, 2 stack;
Wherein the semiconductor stack has an interlayer orientation-based light absorption and light emission characteristics.
The method according to claim 2 or 3,
The first transition metal-chalcogen compound
Molybdenum disulfide (MoS ₂ )
The second transition metal-chalcogen compound
Wherein the tungsten disulfide is tungsten disulfide (WS ₂ ).
The method according to claim 2 or 3,
The first temperature is 660 ° C,
Lt; RTI ID = 0.0 > 800 C. < / RTI >
The method according to claim 1,
The step (c)
Forming an electrical contact on top of the atomic layer of the first and second stacks to measure current;
Partially focusing the light on the first stack through which the current flows, thereby confirming the absorption phase of the photocurrent; And
Analyzing a spectrum of light emitted while entering light of an energy greater than a bandgap of the first stack into the first stack, and comparing the spectra of the light with absorption patterns of the photocurrent;
Wherein the semiconductor stack has an interlayer orientation-based light absorption and light emission characteristics.
The method according to claim 1,
The step (d)
Interlayer transitions of the first and second stacks are observed using ultrafast time-resolved optical pump probe spectroscopy on single interlayer transition dynamics; And
Determining whether the transition band gap is a direct transition band gap through the rate of charge recombination due to the interlayer transition;
Wherein the semiconductor stack has an interlayer orientation-based light absorption and light emission characteristics.
8. The method of claim 7,
In the step (d)
The first stack
Wherein the charge recombination speed is higher than that of the second stack, and the transition band gap is determined to be a direct transition band gap.
The method according to claim 2 or 3,
The coincidence of the crystal orientation
Wherein the first and second transition metal-chalcogen compounds are confirmed to be in conformity with each other through a high-resolution transmission electron microscope.
Method for the analysis of semiconductor stacks with interlayer orientation - based optical absorption and luminescence properties.
(a) preparing a first stack of transition metal-chalcogen compounds with a single atomic layer rotation angle of "0 " with a crystal orientation consistent using chemical vapor deposition;
(b) preparing a second stack of transition metal-chalcogenide compounds whose crystal orientation is inconsistent by adjusting the rotation angle using physical transfer so that the interatomic rotation angle is not "0 ";
(c) measuring an absorption and emission pattern of light between the atomic layers of each of the first and second stacks; And
(d) dynamically analyzing the absorption and emission patterns of the measured light to determine a transition band gap;
Lt; / RTI >
The step (c)
Forming an electrical contact on top of the atomic layer of the first and second stacks to measure current;
Partially focusing the light on the first stack through which the current flows, thereby confirming the absorption phase of the photocurrent; And
Analyzing a spectrum of light emitted while entering light of an energy greater than a bandgap of the first stack into the first stack, and comparing the spectra of the light with absorption patterns of the photocurrent;
/ RTI >
Wherein partial illumination is used for spectral analysis of the light. ≪ RTI ID = 0.0 > 11. < / RTI >
11. The method of claim 10,
The step (d)
Interlayer transitions of the first and second stacks are observed using ultrafast time-resolved optical pump probe spectroscopy on single interlayer transition dynamics; And
Determining whether the transition band gap is a direct transition band gap through the rate of charge recombination due to the interlayer transition;
Wherein the semiconductor stack has an interlayer orientation-based light absorption and light emission characteristics.
12. The method of claim 11,
In the step (d)
The first stack
Wherein the charge recombination speed is higher than that of the second stack, and the transition band gap is determined to be a direct transition band gap.

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