CN117929353A - Semiconductor heterojunction surface enhanced Raman scattering substrate - Google Patents
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- 239000000758 substrate Substances 0.000 title claims abstract description 64
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- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical group [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 30
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical group O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 22
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Abstract
The application relates to the field of Raman scattering, and particularly provides a semiconductor heterojunction surface-enhanced Raman scattering substrate, which comprises a basal layer, wherein a first semiconductor layer is fixedly arranged on one side of the basal layer, a second semiconductor layer is fixedly arranged on one side of the first semiconductor layer, which is far away from the basal layer, the area of the second semiconductor layer is smaller than that of the first semiconductor layer, materials of the first semiconductor layer and the second semiconductor layer are different, and molecules to be detected are arranged on the surface of the substrate during detection. The substrate provided by the application uses the semiconductor heterojunction to enhance the Raman signal. The local electric field on the surface of the heterojunction semiconductor is enhanced by the irradiation of the incident laser; the built-in electric field at the heterojunction semiconductor interface promotes the separation of electron hole pairs and the migration of electrons at the heterojunction interface, so that the electric field intensity of the heterojunction semiconductor surface is increased, and the intensity of Raman signals is further improved. Therefore, the substrate has better effect of enhancing the Raman signal.
Description
Technical Field
The application relates to the field of Raman scattering, in particular to a semiconductor heterojunction surface-enhanced Raman scattering substrate.
Background
The incident laser irradiates on the substance, and scatters, namely, part of photon energy is absorbed by molecules of the substance and generates radiation, the energy of scattered light is different from that of the incident laser, and the obtained scattering spectrum is a Raman signal of the substance. By analyzing the Raman spectrum scattered by the sample, the characteristics of molecular vibration, lattice structure and the like of the sample can be determined; is widely applied in the fields of chemistry, material science, biological science and the like. Raman scattering is a secondary nonlinear process, the probability of raman scattering is relatively low, only a small part of incident photons interact with sample molecules, and only part of photons in the interactions can generate raman scattering to generate raman signals, so that the intensity of the raman signals is small, the influence of background noise is large, and the detection accuracy is low in direct detection.
Surface enhanced raman scattering (Surface-ENHANCED RAMAN SCATTERING, SERS) is a technique that improves the raman scattering signal by inducing electromagnetic field enhancement effects on the Surface of metal or semiconductor nanostructures; the raman signal can be enhanced so that a smaller raman signal can be amplified and thus accurately detected. The document entitled "Recent progress in surface enhanced Raman spectroscopy for the detection of environmental pollutants"（Microchim Acta 2014, 181, 23–43） describes the use of surface-enhanced raman scattering in the field of environmental pollution. Common SERS substrates are noble metal substrates and semiconductor substrates. The noble metal substrate has a higher enhancement factor, and a literature named "Composite structure ofAufilm/PMMA grating coated withAunanocubes forSERSsubstrate"（OPTICAL MATERIALS, 2021,121, 111536） shows that under the action of a gold film, the enhancement factor of a Raman signal reaches 1.45 multiplied by 10 4; however, the price of noble metals such as gold and silver is higher, so that the cost of the noble metal substrate is higher; meanwhile, the noble metal substrate has poor stability due to being easily oxidized. The cost of the semiconductor substrate is lower, and the stability is stronger, so that the semiconductor substrate has better prospect; the advantages of ZnO semiconductors as SERS substrates are described in the literature under the name "Fabrication of Semiconductor ZnO Nanostructures for Versatile SERS Application"（Nanomaterials 2017, 7, 398）. However, the enhancement factor of the semiconductor substrate is smaller, and the enhancement effect of the Raman signal of the molecule to be detected is poorer; further developments are needed to be able to be applied in the field of high sensitivity.
In summary, the enhancement factor of the existing semiconductor SERS substrate is smaller, and the enhancement effect of the raman signal of the molecule to be detected is poorer.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a semiconductor heterojunction surface-enhanced Raman scattering substrate to solve the problems that the enhancement factor of the existing semiconductor SERS substrate is smaller and the Raman signal enhancement effect of molecules to be detected is poor.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the application provides a semiconductor heterojunction surface-enhanced Raman scattering substrate, which comprises a basal layer, wherein a first semiconductor layer is fixedly arranged on one side of the basal layer, a second semiconductor layer is fixedly arranged on one side of the first semiconductor layer, which is far away from the basal layer, the area of the second semiconductor layer is smaller than that of the first semiconductor layer, materials of the first semiconductor layer and the second semiconductor layer are different, and molecules to be detected are arranged on the surface of the substrate during detection.
The molecules to be detected are contacted with part of the surface of the first semiconductor layer and the surface of the second semiconductor layer, incident laser irradiates the molecules to be detected and the substrate, the molecules to be detected scatter incident light, the frequency of the scattered light changes compared with the frequency of the incident light, the change amount of the frequency is related to the characteristic vibration inside the molecules to be detected, and therefore information of the molecules to be detected can be obtained through the scattered light, namely information such as the structure of the molecules to be detected can be obtained through Raman scattering signals. The laser irradiates on the substrate, and effects such as electric field enhancement and the like are generated on the substrate, so that the Raman signal of the molecules to be detected is enhanced, and the molecules to be detected with lower concentration or the molecules with smaller Raman scattering cross section can generate larger Raman scattering signals.
The incident laser irradiates the first semiconductor layer and the second semiconductor layer at the same time, in the first semiconductor layer and the second semiconductor layer, photons interact with electrons on valence bands to enable the electrons to transit to conduction bands to form electron hole pairs, and due to the existence of local charge effects, the formation of the electron hole pairs can cause the change of the charge distribution on the surfaces of the first semiconductor layer and the second semiconductor layer, so that an electric field near the surface is changed, the raman signal of molecules to be detected is stronger due to the enhancement of the local electric field, namely, a larger raman signal enhancement factor is obtained. Because the materials of the first semiconductor layer and the second semiconductor layer are different, the energy band structures of the first semiconductor layer and the second semiconductor layer are different, a built-in electric field is formed at the interface of the first semiconductor layer and the second semiconductor layer, electrons migrate under the action of the built-in electric field, electron hole pairs are separated, and electrons migrate between the first semiconductor layer and the second semiconductor layer, so that the electric field intensity of the surfaces of the first semiconductor layer and the second semiconductor layer is increased, and the Raman signal of molecules to be detected is further enhanced.
The area of the second semiconductor layer is smaller than that of the first semiconductor layer, the surface of the first semiconductor layer can be in contact with molecules to be detected, so that a concentrated light field and a local space of the molecules to be detected are formed on the surface of the first semiconductor layer, on one hand, the areas of the bottom surface (the surface of the first semiconductor layer) and the side surface (the surface of the second semiconductor layer) of the local space are larger, more molecules to be detected can be adsorbed and accumulated, and the total Raman signal intensity generated is larger; on the other hand, the local space plays a local role in the incident laser, and the optical field is not easy to vertically reflect, so that the optical field fully interacts with the first semiconductor layer, the second semiconductor layer and the molecules to be detected, the electric field intensity near the molecules to be detected is enhanced, and the intensity of Raman signals is improved; on the other hand, the local space is closer to the contact surface of the first semiconductor layer and the second semiconductor layer, and the electron migration on the contact surface of the first semiconductor layer and the second semiconductor layer can make the intensity of the nearby electric field stronger, so that the Raman signal of the nearby molecules to be detected is enhanced; in addition, the energy band offset generated during the formation of the heterojunction at the heterojunction interface can also promote the migration of electrons between the two semiconductor layers. Therefore, the substrate has stronger reinforcing effect on the Raman signal of the molecules to be detected and stronger Raman signal of the molecules to be detected.
Further, the refractive index of the material of the second semiconductor layer is smaller than the refractive index of the material of the first semiconductor layer. The light field is transmitted to the second semiconductor layer by air, then enters the first semiconductor layer by the second semiconductor layer, or directly enters the first semiconductor layer by air; the refractive index of air is 1, the refractive index of the second semiconductor layer material is between that of air and that of the first semiconductor layer material, so that an optical field is easy to penetrate through the second semiconductor layer and irradiates the first semiconductor layer, the first semiconductor layer covered by the second semiconductor layer can generate electron hole pairs under the action of the optical field, after the electron hole pairs are separated, the electric field intensity of the surface of the first semiconductor layer is improved, the Raman signal of molecules to be detected is enhanced, meanwhile, more electrons can be provided for the second semiconductor layer through electron migration at an interface, the charge effect of the surface of the second semiconductor layer is stronger, the electric field intensity is higher, and the Raman signal enhancement effect is improved.
Further, the material of the first semiconductor layer is titanium dioxide, and the material of the second semiconductor layer is zinc oxide. Since the work function of titanium oxide is greater than that of zinc oxide material, electrons migrate from titanium oxide to zinc oxide, i.e., electrons migrate from the first semiconductor layer to the second semiconductor layer, at the interface. In this way, on the one hand, the electron concentration in the second semiconductor layer is increased, so that the electric field intensity on the surface of the second semiconductor layer is larger, and the enhancement effect on the Raman signal is better. On the other hand, the second semiconductor layer is not in full contact with the first semiconductor layer, a part of the surface of the first semiconductor layer is in contact with the second semiconductor layer, when electrons migrate from the first semiconductor layer to the second semiconductor layer, a plurality of electron collecting areas are formed on the upper surface of the first semiconductor layer, and electrons move from the corresponding area of the local space of the second semiconductor layer to the corresponding contact area, so that the electric field intensity of the side surface of the second semiconductor layer, namely the side surface of the local space, is increased, and the stronger electric field enables the Raman signal enhancement effect of molecules to be detected in the local space to be better.
Further, a concave structure is arranged on the surface of the side, far away from the substrate layer, of the first semiconductor layer, and the concave structure is arranged on the surface of the first semiconductor layer, where the second semiconductor layer is not arranged. The concave structure increases the contact area between the first semiconductor layer and the molecules to be detected, so that the first semiconductor layer can adsorb more molecules to be detected, and the integral Raman signal is increased; the active area of the incident laser and the first semiconductor layer is increased, meanwhile, the incident laser can be localized by the concave structure, so that the active time between the incident laser and molecules to be detected and the first semiconductor layer is longer, more electron hole pairs can be generated in the first semiconductor layer, the electric field intensity of the surface of the first semiconductor layer is higher, a strong electric field is formed, and the Raman signal intensity is improved; the concave structure on the surface of the first semiconductor layer enables the work function of the first semiconductor layer to be increased, the work function difference between the first semiconductor layer and the second semiconductor layer is increased, electrons are more likely to migrate, and therefore electrons are more likely to migrate from the first semiconductor layer to the second semiconductor layer, the electric field intensity on the surface of the second semiconductor layer is enhanced, and the Raman signal is enhanced; the migration of electrons enhances the enhancement of a built-in electric field between the first semiconductor layer and the second semiconductor layer, so that the separation of electron hole pairs is accelerated, the separation of the electron hole pairs enables the surfaces of the first semiconductor layer and the second semiconductor layer to form a stronger electric field, and the raman signal enhancement effect is better.
Further, the second semiconductor layer has a block array structure. The recesses between adjacent block structures form local spaces, and the block array structure can enable the surface of the first semiconductor layer to form a plurality of local spaces. On the one hand, the local effect of the molecules to be detected and the incident laser is enhanced, so that the interaction among the molecules to be detected, the incident laser, the first semiconductor layer and the second semiconductor layer is stronger, specifically, the interaction among the incident laser, the first semiconductor layer and the second semiconductor layer enables the Raman enhancement effect to be better, the interaction between the incident laser and the molecules to be detected enables the signals of a plurality of molecules to be detected to be superposed, and the strength of the whole Raman signal is higher. On the other hand, the array structure increases the surface area of the semiconductor heterojunction, and increases more surface area in a given space, so that the number of molecules to be detected for generating Raman signals is increased, and the Raman scattering signals are enhanced. In still another aspect, the array structure forms a local electric field enhancement effect at an interface of the first semiconductor layer and the second semiconductor layer, and when light is irradiated to the semiconductor heterojunction surface, the array structure causes the local electric field of the surface to be concentrated and enhanced, thereby improving the enhancement effect of the raman scattering signal.
Further, the side of the substrate layer away from the first semiconductor layer is fixedly provided with a reflecting layer and a supporting layer. The reflection layer can reflect the incident laser and the scattered laser transmitted through the substrate layer, particularly the reflection of the incident laser, so that the incident laser reenters the semiconductor heterojunction, the interaction time between the light field and the semiconductor material and between the light field and molecules to be detected is enhanced, more electrons are generated in the semiconductor layer, and therefore stronger electric fields are generated on the surfaces of the first semiconductor layer and the second semiconductor layer, and the enhancement effect on the Raman signals is better. Compared with background noise, the Raman signal has higher intensity, thereby improving the ratio of the signal to the noise and the signal-to-noise ratio; that is, the reflective layer can also play a role in reducing the influence of background noise, and improves the signal-to-noise ratio of the raman signal, thereby improving the accuracy and reliability of detection. The support layer serves to support and protect the reflective layer and the structure thereon.
Further, the reflecting layer is fixedly connected with the basal layer, and the reflecting layer is fixedly connected with the supporting layer. In this way, the substrate structure is more stable; meanwhile, an air gap does not exist between the reflecting layer and the basal layer, so that energy loss in the light field transmission process is reduced, and the strength of a Raman signal is improved.
Further, the material of the base layer is silicon dioxide. The silicon dioxide has higher transparency in the visible light and near infrared spectrum ranges, so that the light field can pass through and be reflected by the reflecting layer; the silicon dioxide has strong stability and is not easy to react with other substances, so that the substrate is more stable; the silicon dioxide surface has high flatness, and gaps are not easy to generate between adjacent layer structures, so that the energy barrier on the contact surface is increased, and the enhancement of a Raman signal is not facilitated.
Further, the material of the reflecting layer is metallic silver. The metallic silver has very high reflectivity in the visible light and near infrared spectrum ranges, so that the metallic silver can play a good role in reflecting the light field. Further, the thickness of the support layer is 1-3mm. The thickness is not easy to deform, so that the shape and the flatness of the substrate are maintained, and the stability of the substrate is improved; the thicker support layer can reduce the influence of the support layer on the Raman signal, and reduce the scattering and background noise from the support layer, thereby improving the accuracy and reliability of detection.
Compared with the prior art, the application has the beneficial effects that: the substrate provided by the application uses the semiconductor heterojunction to enhance the Raman signal. The incident laser irradiates on the surfaces of the first semiconductor layer and the second semiconductor layer, electron hole pairs are generated in the first semiconductor layer and the second semiconductor layer, and the charge distribution of the surfaces of the first semiconductor layer and the second semiconductor layer is changed, so that a local electric field is enhanced, and a Raman signal of molecules to be detected is enhanced. The different energy band structures enable a built-in electric field to be generated at the heterojunction interface, separation of electron hole pairs and migration of electrons at the heterojunction interface are promoted, and the electric field intensity of the surfaces of the first semiconductor layer and the second semiconductor layer is increased, so that the intensity of a Raman signal is further improved. The local space formed between the surfaces of the first semiconductor layer and the second semiconductor layer plays a role in local area of molecules to be detected and incident laser, so that the incident laser fully acts on the first semiconductor layer and the second semiconductor layer to promote Raman signals of the molecules to be detected, the local area of the molecules to be detected enables more molecules to be detected to be irradiated by the incident laser to generate Raman signals, and meanwhile the Raman signals are enhanced by the heterojunction semiconductor, so that the overall Raman signal intensity is larger. Therefore, the substrate has better effect of enhancing the Raman signal.
Drawings
Fig. 1 is a schematic diagram of a semiconductor heterojunction surface enhanced raman scattering substrate provided by the invention;
FIG. 2 is a schematic diagram of another semiconductor heterojunction surface-enhanced Raman scattering substrate provided by the invention;
fig. 3 is a schematic top view of another semiconductor heterojunction surface-enhanced raman scattering substrate provided by the present invention.
Icon: 1-a substrate layer; 2-a first semiconductor layer; 3-a second semiconductor layer; a 4-reflective layer; 5-supporting layer.
Detailed Description
In order to make the implementation of the present invention more clear, the following detailed description will be given with reference to the accompanying drawings.
Example 1:
The invention provides a semiconductor heterojunction surface-enhanced Raman scattering substrate, which comprises a basal layer 1, a first semiconductor layer 2 and a second semiconductor layer 3 as shown in figure 1. The semiconductor device comprises a second semiconductor layer 3, a first semiconductor layer 2 and a substrate layer 1 from top to bottom in sequence, wherein the first semiconductor layer 2 and the substrate layer 1 are fixedly connected, and the second semiconductor layer 3 and the first semiconductor layer 2 are also fixedly connected. Specifically, the second semiconductor layer 3 and the first semiconductor layer 2 are fixedly arranged together through chemical bond acting force or van der waals acting force to form a heterojunction; in the heterojunction forming process, the fermi level in the material with higher fermi level in the second semiconductor layer 3 and the first semiconductor layer 2 is reduced, the fermi level in the material with lower fermi level is increased, the fermi levels of the two materials are the same, energy band offset is generated at the interface, migration of electrons at the interface is promoted, the intensity of a built-in electric field is also enabled to be larger, and therefore the electric field intensity on the surface of the semiconductor heterojunction is enabled to be larger, and particularly the electric field intensity in a local space is enabled to play a good role in enhancing a Raman signal of molecules to be detected. The materials of the first semiconductor layer 2 and the second semiconductor layer 3 are different, the refractive index of the material of the second semiconductor layer 3 is smaller than the refractive index of the material of the first semiconductor layer 2, preferably the material of the first semiconductor layer 2 is titanium dioxide and the material of the second semiconductor layer 3 is zinc oxide. The material of the base layer 1 is silica.
The thickness of the first semiconductor layer 2 is larger than that of the second semiconductor layer 3, and the thickness of the first semiconductor layer 2 and the thickness of the second semiconductor layer are smaller than the incidence depth of incident laser, so that the laser can act on the surfaces and the interiors of the first semiconductor layer 2 and the second semiconductor layer 3 simultaneously, electrons excited by the interiors can move to the surfaces, the local electric field intensity of the semiconductor heterojunction surface is enhanced, and Raman signals are effectively improved. The thickness of the second semiconductor layer 3 is thinner, on one hand, electrons in the second semiconductor layer can reach the surface rapidly to interact with molecules to be detected, so that a Raman signal of the molecules can be enhanced, and on the other hand, an optical field can fully act with the first semiconductor layer 2, more electrons are generated in the first semiconductor layer 2, the surface local electric field intensity of the electrons is enhanced, and finally the Raman signal is enhanced. Electrons in the first semiconductor layer 2 are transferred to the second semiconductor layer 3 through the interface, the thickness of the first semiconductor layer 2 is larger, more electrons can be provided, the electric field intensity on the surface of the second semiconductor layer 3 is stronger, and the Raman signal of molecules to be detected is enhanced more. In addition, the first semiconductor layer 2 is thicker, and is convenient to improve on the surface of the first semiconductor layer, so that the local effect of an electric field is stronger, thereby improving the enhancement factor and the strength of a Raman signal. Specifically, the thickness of the first semiconductor layer 2 is 50nm to 80 μm, and the thickness of the second semiconductor layer 3 is 20 to 100nm. In addition, the absorption coefficient of the titanium dioxide is larger than that of zinc oxide, the zinc oxide has smaller absorption to light, and the laser is easier to transmit the zinc oxide to irradiate the titanium dioxide, so that the first semiconductor layer 2 covered by the second semiconductor layer 3 can also contribute to the promotion of the Raman scattering signal. The thickness of the basal layer 1 is 1-5mm, so that the deformation resistance is strong, the deformation is not easy to generate, and the semiconductor heterojunction on the basal layer has good supporting and protecting effects. The area of the second semiconductor layer 3 is smaller than the area of the first semiconductor layer 2. In detection, incident laser irradiates the surface of the heterojunction semiconductor, and part of the surfaces of the second semiconductor layer 3 and the first semiconductor layer 2 are in contact with molecules to be detected.
During preparation, the substrate layer 1 is cleaned, dried and the surface of the substrate layer is ensured to be clean; then evaporating or depositing or sputtering a first semiconductor layer 2 on the substrate layer 1, wherein the first semiconductor layer 2 is prepared by adopting a vacuum coating mode. Vacuum coating is a process of evaporating or sputtering a material in atomic or molecular form from a solid source onto a substrate surface; the material is heated to a vapor pressure high enough to evaporate and then the vapor is delivered to the substrate surface by a vacuum system to deposit the material into a thin film. The material is a massive titanium dioxide material. The substrate layer 1 deposited with titanium dioxide is taken as a substrate, zinc oxide is deposited on the substrate, and preferably, the method is prepared by using a vapor deposition method, wherein the vapor deposition method is a method for depositing a layer of film material on the surface of a solid substrate, precursor powder is converted into a gas state in the heating process, the precursor is reacted under the driving of carrier gas, and vapor precursor molecules are deposited into a solid film on the surface of the substrate through pyrolysis or chemical reaction. The uniformity of the film obtained by the vapor deposition method is good. The precursor in the application can be dimethyl zinc or methyl zinc ketone; the deposition temperature is about 400 ℃ to 600 ℃. The zinc oxide film obtained by the chemical vapor deposition method has strong uniformity, more active sites are generated on the surface, more molecules to be detected can be adsorbed, and the Raman signal of the molecules to be detected is enhanced. The purity of the film obtained by the vacuum coating mode is higher, titanium dioxide is contacted with zinc oxide obtained by chemical vapor deposition, the contact between the titanium dioxide and the zinc oxide is tighter in the chemical vapor deposition process, the acting force of the contact surface of the titanium dioxide and the zinc oxide is stronger, and the structure is more stable. Finally, removing part of the second semiconductor layer 3 by adopting an ion beam bombardment mode; ion beam bombardment is a common surface modification technique that uses an ion beam to strike the surface of a material and strip atoms or molecules of the material from the surface, thereby effecting processing of the material.
Example 2:
In order to further enhance the enhancement effect of the raman signal, on the basis of embodiment 1, a concave structure is provided on the surface of the side of the first semiconductor layer 2 away from the base layer 1, and the concave structure is provided on the surface of the first semiconductor layer 2 where the second semiconductor layer 3 is not provided. The cross section of the concave can be in a wedge shape with the inner part being narrow and the outer part being wide, so that the light field is reflected on the inclined planes at the two sides and is not easy to be transmitted out, the local effect of the concave structure on the light field is better, the electric field intensity at the bottom of the wedge-shaped concave is stronger, and the Raman signal enhancement effect of molecules to be detected is stronger; the second semiconductor layer 3 may be prepared conveniently by appropriately extending the ion beam bombardment time when the ion beam is used to bombard the second semiconductor layer 3, so that the ion beam continues to bombard the first semiconductor layer 2, and a concave structure can be prepared on the surface of the first semiconductor layer 2. The depth of the concave structure is one third to one half of the thickness of the first semiconductor layer 2, so that the light field can be ensured to be fully irradiated into the concave structure, the raman scattering signal can be ensured to be scattered out, and the raman signal is difficult to transmit out due to the too deep depth of the concave structure, so that the intensity of the raman signal is reduced; on the other hand, the local effect of the concave structure on the light field makes the electric field intensity inside the concave structure stronger, thereby leading to the localization of electrons inside the first semiconductor layer 2, in addition, the defect state on the surface of the concave structure can also enhance the capture capability of the concave structure on electrons, the localization of electrons is further enhanced, the localized electrons in the first semiconductor layer 2 can influence the transmission path of electrons therein, and when the concave structure is deeper, the transverse movement of electrons is larger, thereby reducing the integral electric field intensity on the surface of the first semiconductor layer 2, and further reducing the effect of enhancing the raman scattering signal.
The width of the recess structure is the same as the width of the exposed surface of the first semiconductor layer 2, that is, the same as the pitch between adjacent second semiconductor blocks, as shown in fig. 2; in this way, the edge of the concave structure is in direct contact with the second semiconductor layer 3, so that electrons in the first semiconductor layer 2 can more easily enter the concave structure directly, the electric field intensity on the side wall of the concave structure is stronger, the local electric field effect inside the concave structure is enhanced, and the effect of enhancing the Raman signal is achieved. Preferably, the second semiconductor layer 3 is in a block array structure, and may be arranged in a rectangular array as shown in fig. 3, so that adjacent concave structures are mutually communicated, that is, the concave structures are longitudinally and longitudinally communicated, so that ion beams do not need to be designed and arranged, and the ion beam is convenient to prepare. The n-th row and the n+2-th row are aligned in a staggered manner, the n+1-th row is not aligned with the adjacent two rows, and is opposite to the middle position of the adjacent semiconductor blocks in the direction of the rows, so that the adjacent concave structures are not communicated, the surface junction of the concave structures is increased, namely the surface area of the first semiconductor layer 2 is increased, and the local effect of the concave structures on the light field and the molecules to be detected can be improved due to the limitation of four directions, so that the Raman signal intensity of the molecules to be detected is higher. Different ion beam distributions are required for the preparation of different array arrangements. The shape of the block array structure unit in the second semiconductor layer 3 is cuboid or cube, the size is 50-80nm, the array spacing is smaller than 30nm, the transverse spacing and the longitudinal spacing can be equal or unequal, and the coupling can be generated between the adjacent second semiconductor blocks due to the fact that the transverse spacing and the longitudinal spacing are smaller than 30nm, so that the intensity of a local electric field is stronger, the Raman signal intensity of molecules to be detected is higher, and the enhancement factor is further improved.
Example 3:
On the basis of embodiment 1 or embodiment 2, the side of the base layer 1 remote from the first semiconductor layer 2 is fixedly provided with a reflective layer 4 and a support layer 5. The reflecting layer 4 is fixedly connected with the substrate layer 1, and the reflecting layer 4 is fixedly connected with the supporting layer 5. The material of the reflective layer 4 is metallic silver. This embodiment differs from embodiment 1 and embodiment 2 in that the thickness of the base layer 1 is 80 to 100nm, so that incident laser light can be transmitted through the base layer 1 and irradiated on the reflecting layer 4. The thickness of the reflecting layer 4 is larger than 150nm, so that a good reflecting effect can be achieved. The supporting layer 5 is made of silicon or silicon nitride, the thickness of the supporting layer 5 is 1-3mm, and the supporting layer 5 plays a role in supporting and protecting the reflecting layer 4, the basal layer 1, the first semiconductor layer 2 and the second semiconductor layer 3.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The semiconductor heterojunction surface-enhanced Raman scattering substrate is characterized by comprising a base layer, wherein a first semiconductor layer is fixedly arranged on one side of the base layer, a second semiconductor layer is fixedly arranged on one side of the first semiconductor layer away from the base layer, the area of the second semiconductor layer is smaller than that of the first semiconductor layer, materials of the first semiconductor layer and the second semiconductor layer are different, and molecules to be detected are arranged on the surface of the substrate during detection.
2. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 1, wherein the refractive index of the material of the second semiconductor layer is smaller than the refractive index of the material of the first semiconductor layer.
3. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 2, wherein the material of the first semiconductor layer is titanium dioxide and the material of the second semiconductor layer is zinc oxide.
4. A semiconductor heterojunction surface enhanced raman scattering substrate according to claim 3, wherein a recess structure is provided on a side surface of the first semiconductor layer remote from the base layer, the recess structure being provided on the surface of the first semiconductor layer where the second semiconductor layer is not provided.
5. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 4, wherein the second semiconductor layer is a bulk array structure.
6. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 5, wherein the base layer is fixedly provided with a reflecting layer and a supporting layer at a side far away from the first semiconductor layer.
7. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 6, wherein the reflective layer is fixedly connected to the base layer, and the reflective layer is fixedly connected to the supporting layer.
8. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 1, wherein the material of the base layer is silicon dioxide.
9. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 6, wherein the material of the reflective layer is metallic silver.
10. The semiconductor heterojunction surface enhanced raman scattering substrate of claim 6, wherein the thickness of the support layer is 1-3mm.
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