Real-time in-situ spectrum integrated measurement method and device based on single-side single reflection

Abstract

The invention discloses a real-time in-situ spectrum integrated measurement method and device based on single-side single reflection. According to the invention, the reflectivity of the thin film-reflecting surface system is measured at one side and one time, the light intensity transmittance of the thin film is directly calculated, and the dielectric constant of the thin film material and the thickness of the thin film do not need to be known in advance; the transmittance spectrum of the thin film can be obtained by measuring the transmittance of the thin film with different wavelengths; in the process, the reflected light intensity of the film-reflecting surface system is only measured once, and the amplitude superposition of light or the interference of light is not involved; more importantly, the incident light and the light returned by the reflecting surface along the same path are collinear and are positioned on the same side of the sample, so that the whole measuring system is very compact and easy to integrate; the incident angle is further increased, and light reflected by the surface of the film and light reflected by the reflecting surface cannot be measured by the system, so that the measuring device can directly measure the fluorescence spectrum of the film under the excitation of continuous light or monochromatic light.

Description

Technical Field

[0001] The invention relates to an optical thin film measurement technology, and in particular to a real-time in-situ spectrum integrated measurement method based on single-side single reflection and an integrated measurement device thereof. Background Art

[0002] Thin films are widely used in modern photonics and optoelectronics fields such as photovoltaics, storage, and chips. They can be used to manufacture various optoelectronic devices, chips, and instruments. The properties of thin films, such as material properties, thickness, and uniformity, are crucial to the performance of optoelectronic devices and chips. The optical properties of materials can be characterized by measuring transmittance or absorbance. In addition, integrating the measurement of thin film transmittance or absorbance with film-making equipment to achieve real-time in-situ measurement of the film growth process can be used to study the kinetics of the film-making process, which is very important for understanding and optimizing device functions.

[0003] There are two main methods for measuring the transmittance or absorbance of thin films: reflection type and transmission type. Film thickness meters and ellipsometers based on reflection systems both use the principle of thin film interference to measure the reflected light of the film to study the properties of the film, such as the film thickness and the complex refractive index of the material. The transmittance or absorbance of the film can be further calculated based on the film thickness and the complex refractive index of the material. The physical essence of this reflection system instrument (ellipsometer and film thickness meter) is based on multiple reflections of light at the interface of different materials. The interference spectrum is obtained by superimposing the amplitudes of these reflected lights, and then a complex fitting formula is used to obtain the film thickness or complex refractive index. This method must know one of the parameters of the film thickness and the complex refractive index in order to fit the other parameter through a formula. Although the probe of this film thickness meter is very small (about 30mm 2 ), which is easy to integrate, but in the process of thin film material growth, both the film thickness and material properties are unknown, so it is impossible to fit the interference spectrum, and the film thickness meter cannot achieve real-time in-situ measurement of the film growth process. In addition, for a single-wavelength light source, it is impossible to fit the formula, and the film thickness meter cannot obtain the complex refractive index of the material at a single wavelength. The ellipsometer is based on measuring the change in the polarization state of the reflected light of the film, using precise optical models and complex calculations to simultaneously solve the film thickness and the complex refractive index of the material, thereby achieving real-time in-situ measurement of the film. However, this reflective ellipsometer requires large oblique light incidence (the incident angle θ is about 70°), and a detector or spectrometer must be set at the corresponding angular position (-θ, the reflected light beam position), which makes the entire optical system bulky and difficult to integrate.

[0004] Film thickness meters and ellipsometers based on reflection systems do not use the transmitted light part and cannot directly measure the transmittance of the film. Instruments such as spectrophotometers based on transmission systems can directly measure the transmittance or absorbance of the film. This transmission system requires incident light from one side of the sample and collects the transmitted light from the other side of the sample to achieve measurement. The configuration of this transmission system makes the entire measurement system large and difficult to integrate. Usually, when a transmission system is integrated with a device, the device to be integrated needs to be modified, which seriously affects its versatility and practicality. For example, when a transmission system with a dual fiber head is integrated with a spin coater or a heating annealing table, a hole needs to be drilled in the center of the spin coater or the heating annealing table, running through the entire instrument from bottom to top, to place one of the fiber heads and allow the light beam to pass through. However, some film-making equipment is not convenient to drill holes through, such as large-area coaters, vacuum heating / cooling coating equipment [molecular beam epitaxy (MBE) equipment and electron beam evaporation (Ebeam) equipment], etc., so it is difficult to integrate with the transmission system. In summary, it is still a huge challenge to obtain a method and device that is small in size, easy to integrate, and can measure the transmittance (or absorbance) of a thin film in real time and in situ. Summary of the invention

[0005] In order to solve the above-mentioned problems, the present invention proposes a real-time in-situ spectral integrated measurement method based on single-sided single reflection and an integrated measurement device thereof, which realizes real-time in-situ measurement of the transmission spectrum of a thin film by using the single-sided single reflection method without knowing the complex refractive index and the thickness of the thin film material in advance; further, the measuring device is integrated with a commonly used spin coater and a heating annealing table without modifying the integrated instrument, and the experiment demonstrates real-time in-situ spectral monitoring of the transmission spectrum during the growth of perovskite thin films.

[0006] An object of the present invention is to provide a real-time in-situ spectral integrated measurement method based on single-side single reflection.

[0007] The real-time in-situ spectral integrated measurement method based on single-side single reflection of the present invention comprises the following steps:

[0008] 1) Build a real-time in-situ spectral integrated measurement device:

[0009] The film to be measured is placed on a transparent substrate, with the environment above the film; the substrate transmittance T s ≥5%;

[0010] The substrate is placed on the reflection surface to form a film-reflection surface system, and the reflection surface is placed on the sample stage; the reflection surface is a plane reflection surface or a curved reflection surface; when the reflection surface is a plane reflection surface, the angle between the surface of the film to be measured and the plane where the reflection surface is located is the tilt angle β; when the reflection surface is a curved reflection surface, the angle between the surface of the film to be measured and the tangent plane of the reflection point is the tilt angle β, β>0;

[0011] An incident light path and an outgoing light path are arranged above the film; a light source is coupled to the incident light path, an end of the outgoing light path is coupled to a detector or a spectrometer, and the detector or the spectrometer is connected to a computer;

[0012] 2) Beam propagation:

[0013] Parallel beam: The light emitted by the light source is collimated and becomes a parallel beam, which is incident on the film through the incident light path. The light intensity of the beam is I0. The incident light is incident on the surface of the film at an incident angle α, α=β>0, and part of the light is reflected into the environment. The other part of the light is refracted by the film and the substrate and vertically incident on the reflecting surface, and then vertically reflected by the reflecting surface and returned along the original path, and finally refracted from the upper surface of the film into the environment.

[0014] Divergent beam: The light emitted by the light source is not collimated to form a divergent beam that is incident on the film through the incident light path. The light intensity of the beam is I0, and the divergence angle is γ = arcsin (NA), where NA is the numerical aperture of the optical fiber or lens in the output light path; the central light of the divergent beam, i.e., the principal light, is incident on the surface of the film at an incident angle α, where α> arcsin (NA) and α≥β>

[0015] 0, part of the light is reflected into the environment, and the part of the divergent light beam that is perpendicular to the reflecting surface, that is, the light with an angle of (α-β) with the main light, is refracted by the film and the substrate and vertically incident on the reflecting surface, then vertically reflected by the reflecting surface and returned along the original path, and finally refracted from the upper surface of the film into the environment;

[0016] 3) Beam reception:

[0017] The light beam refracted from the upper surface of the film-reflecting surface system to the environment is received by a detector or a spectrometer through the outgoing light path, and the light intensity I of the light beam refracted from the upper surface of the film-reflecting surface system to the environment is obtained. R ;

[0018] 4) Light intensity formula:

[0019] The intensity of the light beam refracted from the upper surface of the film-reflector system to the environment is I R satisfy:

[0020] I R =I0×T×T s ×R m ×T s ×T

[0021] Where T is the light intensity transmittance of the film, T s is the light intensity transmittance of the substrate, R m is the light intensity reflectivity of the reflecting surface;

[0022] 5) Reflectivity formula:

[0023] According to the light intensity formula in step 4), the reflectivity R of the film-reflecting surface system is obtained as:

[0024]

[0025] 6) Get the transmittance:

[0026] According to the known light intensity transmittance T of the substrate s and the light intensity reflectivity R of the reflective surface m , using the reflectivity formula in step 5), the light intensity transmittance T of the film is further obtained:

[0027]

[0028] Therefore, the light intensity transmittance T of the film can be directly calculated by measuring the reflectivity R of the film-reflecting surface system without knowing the complex refractive index of the film material and the thickness of the film in advance. This is suitable for real-time in-situ measurement during the film growth process.

[0029] Wherein, in step 1), the reflective surface adopts a reflective mirror or a reflective film. The sample stage adopts a bracket, a support frame, a support shell or a block support.

[0030] The light source uses a multi-wavelength light source to directly measure the film transmission spectrum; or, the light source uses a monochromatic light source to measure the film transmittance at one wavelength.

[0031] The incident light path and the outgoing light path adopt an optical fiber transmission system or a free space transmission system; when the optical fiber transmission system is adopted, the incident light path adopts an incident optical fiber, and the outgoing light path adopts an outgoing optical fiber; when the free space transmission system is adopted, the incident light path adopts a first lens, and the outgoing light path adopts a second lens. In the incident light path, the incident light is collimated by the first lens and then incident on the upper surface of the film through a beam splitter. In the outgoing light path, the outgoing light is collected by the second lens after passing through the beam splitter and coupled to a detector or a spectrometer. The beam splitter adopts a beam splitter prism or a beam splitter.

[0032] In step 2), for a parallel light beam, when α=β>0, the reflected light from the upper and lower surfaces of the film cannot return to the original path to be collected and measured by the measuring system, and only the light vertically reflected by the reflecting surface returns along the original path to be collected; for a divergent light beam, when α is greater than arcsin (NA), the reflected light from the upper and lower surfaces of the film cannot enter the optical fiber or lens to be collected by it, and only the light vertically reflected by the reflecting surface returns along the original path to be collected; wherein NA is the numerical aperture of the optical fiber or lens.

[0033] Another object of the present invention is to provide a real-time in-situ spectral integrated measurement device based on single-side single reflection.

[0034] The real-time in-situ spectral integrated measurement device based on single-side single reflection of the present invention comprises: a substrate, a reflection surface, a sample stage, a light source, an incident light path, an outgoing light path, a detector or a spectrometer and a computer;

[0035] The film to be measured is placed on a transparent substrate, with the environment above the film. The substrate transmittance T s ≥5%;

[0036] The substrate is placed on the reflective surface to form a film-reflective surface system, and the reflective surface is placed on the sample stage; the reflective surface is a plane reflective surface or a curved reflective surface; when the reflective surface is a plane reflective surface, the angle between the film surface to be measured and the plane where the reflective surface is located is the tilt angle β; when the reflective surface is a curved reflective surface, the angle between the film surface to be measured and the tangent plane of the reflection point is the tilt angle β, β>0;

[0037] An incident light path and an outgoing light path are arranged on the film; a light source is coupled to the incident light path, an end of the outgoing light path is coupled to a detector or a spectrometer, and the detector or the spectrometer is connected to a computer;

[0038] When the light emitted by the light source is collimated and becomes a parallel beam that is incident on the film through the incident light path, the light intensity of the beam is I0; the incident light is incident on the surface of the film at an incident angle α, α=β>0, part of the light is reflected into the environment, and the other part of the light is refracted by the film and the substrate and incident on the reflecting surface, and then is vertically reflected by the reflecting surface and returns along the original path, and finally refracted from the upper surface of the film into the environment; or, the light emitted by the light source is not collimated to form a divergent beam that is incident on the film through the incident light path, the light intensity of the beam is I0, and the divergence angle is γ=arc sin(NA), NA is the numerical aperture of the optical fiber or lens in the outgoing light path; the principal ray of the divergent light beam, i.e., the ray in the middle of the divergent light beam, is incident on the surface of the film at an incident angle α, α>arcsin(NA) and α≥β>0, a part of the light is reflected into the environment, and the part of the light in the divergent light beam that is perpendicular to the reflection surface, i.e., the light with an angle of (α-β) with the principal ray, is refracted by the film and the substrate and vertically incident on the reflection surface, then vertically reflected by the reflection surface and returned along the original path, and finally refracted from the upper surface of the film into the environment;

[0039] The light beam refracted from the upper surface of the film-reflecting surface system to the environment is received by a detector or a spectrometer through an outgoing optical path to obtain the light intensity of the light beam refracted from the upper surface of the film-reflecting surface system to the environment; the reflectivity of the film-reflecting surface system is obtained according to the light intensity; and the light intensity transmittance T of the substrate is known. s and the light intensity reflectivity R of the reflective surface m , and the reflectivity of the film-reflecting surface system, the light intensity transmittance of the film is obtained.

[0040] The curved reflection surface is a surface that is a tangent plane of the incident light perpendicular to the incident point. The curved reflection surface may be a spherical reflection surface, a conical reflection surface or other curved reflection surfaces.

[0041] Furthermore, the real-time in-situ spectral integrated measurement device based on single-side single reflection of the present invention is integrated with a film-making device to achieve real-time in-situ monitoring of the transmission spectrum of the film growth process. The film-making device is a spin coater, a heating annealing table or a coating machine.

[0042] Advantages of the present invention:

[0043] The present invention directly calculates the light intensity transmittance of the film by measuring the reflectivity of the film-reflecting surface system on one side and once, without knowing the dielectric constant of the film material and the thickness of the film in advance; the transmittance spectrum of the film can be obtained by measuring the transmittance of the film at different wavelengths; this process only measures the reflected light intensity of the film-reflecting surface system once, and does not involve the amplitude superposition of light or the interference of light; more importantly, the incident light and the light returned by the reflecting surface are collinear and on the same side of the sample, which makes the entire measurement system very compact and easy to integrate; further increasing the incident angle, the light reflected from the film surface and the light reflected from the reflecting surface will not be measured by the system, so the measuring device can directly measure the fluorescence spectrum of the film under the excitation of continuous light or monochromatic light. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The transmittance principle diagram of the real-time in-situ spectral integrated measurement method based on single-side single reflection of the present invention, wherein: (a) is a schematic diagram of a plane reflection surface, in which the light beam is perpendicular to the horizontal plane; (b) is a schematic diagram of a plane reflection surface, in which the light beam is inclined to the horizontal plane; (c) is a schematic diagram of a spherical reflection surface, in which the light beam is perpendicular to the horizontal plane; (d) is a schematic diagram of a spherical reflection surface, in which the light beam is inclined to the horizontal plane; (e) is a schematic diagram of a conical reflection surface, in which the light beam is inclined to the horizontal plane; (f) is a schematic diagram of other curved reflection surfaces, in which the light beam is inclined to the horizontal plane;

[0045] Figure 2 Schematic diagram of the real-time in-situ spectral integrated measurement device based on single-side single reflection of the present invention, wherein (a) is a schematic diagram of the optical fiber transmission system - vertical light incidence; (b) is a schematic diagram of the optical fiber transmission system - oblique light incidence; (c) is a schematic diagram of the free space transmission system;

[0046] Figure 3 The result graphs of the reflection spectrum and the transmission spectrum of the perovskite film are obtained according to an embodiment of the real-time in-situ spectral integrated measurement method based on single-side single reflection of the present invention, wherein (a) is the result graph of the film thickness h=240nm; (b) is the result graph of the film thickness h=190nm; (c) is the result graph of the film thickness h=130nm;

[0047] Figure 4 Schematic diagram of an experimental device for integrating the real-time in-situ spectral integrated measurement method based on single-side single reflection of the present invention with other film-making equipment, (a) is a schematic diagram of integration with a spin coater; (b) is a schematic diagram of integration with a heating annealing station;

[0048] Figure 5 The results of the real-time in-situ measurement of the time evolution of the transmittance spectrum of the perovskite film during the annealing process by the real-time in-situ spectral integrated measurement method based on single-side single reflection of the present invention are shown in Fig. (a) to (c) are the results of the time evolution of the transmittance spectrum of the perovskite film prepared by inks of different concentrations during annealing for 0 to 20 seconds and 0 to 600 seconds, respectively;

[0049] Figure 6 It is a schematic diagram of the integrated application of the real-time in-situ spectral integration device based on single-side single reflection and the film-making equipment of the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0051] The real-time in-situ spectral integrated measurement device based on single-side single reflection of this embodiment comprises: a substrate, a reflection surface, a sample stage, a light source, an incident light path, an outgoing light path, a spectrometer and a computer;

[0052] The film to be measured is placed on a transparent substrate, with the environment above the film. The substrate transmittance T s ≥5%;

[0053] like Figure 1 As shown, the substrate is placed on the reflecting surface to form a film-reflecting surface system, and the reflecting surface is set on the sample table; the reflecting surface is a plane reflecting surface or a curved reflecting surface; when the reflecting surface is a plane reflecting surface, the angle between the film surface to be measured and the plane where the reflecting surface is located is the tilt angle β; when the reflecting surface is a curved reflecting surface, the angle between the film surface to be measured and the tangent plane of the reflection point is the tilt angle β, β>0. Figure 1 In the figure, (a) is a plane reflection surface, and the light beam is perpendicular to the horizontal plane; (b) is a plane reflection surface, and the light beam is inclined to the horizontal plane; (c) is a spherical reflection surface, and the light beam is perpendicular to the horizontal plane; (d) is a spherical reflection surface, and the light beam is inclined to the horizontal plane; (e) is a conical reflection surface, and the light beam is inclined to the horizontal plane; (f) is other curved reflection surfaces that are the cross-sections of the incident light perpendicular to the incident point, and the light beam is inclined to the horizontal plane.

[0054] like Figure 2As shown, an incident light path and an outgoing light path are arranged on the film; a light source is coupled to the incident light path, and the end of the outgoing light path is coupled to a detector or a spectrometer, and the detector or the spectrometer is connected to a computer. The incident light path and the outgoing light path adopt an optical fiber transmission system or a free space transmission system; when the optical fiber transmission system is adopted, the incident light path adopts an incident optical fiber, and the outgoing light path adopts an outgoing optical fiber; when the free space transmission system is adopted, the incident light path adopts a first lens, and the outgoing light path adopts a second lens. In the incident light path, the incident light is collimated by the first lens and then incident on the upper surface of the film through a beam splitter element. In the outgoing light path, the outgoing light is collected by the second lens after passing through the beam splitter element and coupled to the spectrometer. The beam splitter element adopts a beam splitter prism or a beam splitter. Figure 2 In the figure, (a) is a fiber transmission system with vertical light incidence; (b) is a fiber transmission system with oblique light incidence; (c) is a free space transmission system. Only three measurement devices are shown here, the fiber transmission system and the free space transmission system. Figure 1 All cases in can be integrated separately.

[0055] When the light emitted by the light source is collimated and becomes a parallel beam that is incident on the film through the incident light path, the light intensity of the beam is I0; the incident light is incident on the surface of the film at an incident angle α, α=β>0, part of the light is reflected into the environment, and the other part of the light is refracted by the film and the substrate and incident on the reflecting surface, and then is vertically reflected by the reflecting surface and returns along the original path, and finally refracted from the upper surface of the film into the environment; or, the light emitted by the light source is not collimated to form a divergent beam that is incident on the film through the incident light path, the light intensity of the beam is I0, and the divergence angle is γ=arc sin(NA), NA is the numerical aperture of the optical fiber or lens in the output light path; the principal ray of the divergent light beam, i.e., the ray in the middle of the divergent light beam, is incident on the surface of the film at an incident angle α, α>arcsin(NA) and α≥β>0, a part of the light is reflected into the environment, and the part of the light in the divergent light beam that is perpendicular to the reflecting surface, i.e., the light with an angle of (α-β) with the principal ray, is refracted by the film and the substrate and vertically incident on the reflecting surface, and then is vertically reflected by the reflecting surface and returns along the original path, and finally refracted from the upper surface of the film into the environment.

[0056] The light beam refracted from the upper surface of the film-reflecting surface system to the environment is received by the spectrometer through the outgoing optical path, and the light intensity I of the light beam refracted from the upper surface of the film-reflecting surface system to the environment is measured. R ,satisfy:

[0057] I R =I0×T×T s ×R m ×T s ×T

[0058] Where T is the light intensity transmittance of the film, T s is the light intensity transmittance of the substrate, Rm is the light intensity reflectivity of the reflective surface; according to the light intensity formula, the reflectivity R of the film-reflective surface system is obtained as:

[0059]

[0060] When the light intensity transmittance of the substrate is T s and the light intensity reflectivity R of the reflective surface m When it is known, the above reflectivity formula is used to further obtain the light intensity transmittance T of the film:

[0061]

[0062] Thus, the light intensity transmittance T of the film can be directly calculated by measuring the reflectivity R of the film-reflecting surface system, without knowing the complex refractive index of the film material and the thickness of the film in advance. This method is suitable for real-time in-situ measurement during the film growth process.

[0063] Use Figure 2 The experiment was conducted using the optical fiber transmission system shown in (a). The numerical aperture of the optical fiber used in the experiment was NA = 0.22 ± 0.02, and the corresponding divergence angle was 12.5°. The incident optical fiber and the output optical fiber have a common port, which is fixed by a five-axis optical fiber holder. The five-axis optical fiber holder adjusts the three-dimensional position of the optical fiber on the film and adjusts the pitch of the optical fiber so that the optical fiber is perpendicular to the surface of the film. The sample stage used in the experiment is Figure 1 (a) shows a plane reflective surface and the light beam is perpendicular to the horizontal plane. The sample stage is made of copper. The tilt angle α on the upper surface of the sample stage is 13.1°, which is greater than the optical fiber divergence angle of 12.5°. Therefore, the optical fiber probe only collects the light reflected from the plane reflective surface, but does not collect the reflected light from the upper and lower surfaces of the film. The reflection spectrum and transmission spectrum of the perovskite MAPbI3 film-reflective surface system were measured in the experiment. The substrate under the film is made of glass, such as Figure 3 shown. Figure 3In (a), the thickness of the MAPbI3 film is h = 240nm, the dashed line is the reflectance spectrum of the MAPbI3 film-reflecting surface system measured by the device, the solid line is the calculated transmittance spectrum of the MAPbI3 film, and the dashed line is the transmittance spectrum of the MAPbI3 film with a thickness of h = 240nm measured by a spectrophotometer. It can be seen from the reflectance spectrum of the MAPbI3 film-reflecting surface system with the dashed line that in the long-wave band (λ>780nm), the absorption of the perovskite film is very small, and the energy loss of light reaching the reflective surface through the film and the substrate is small, so the light reflected by the copper reflective surface is very strong (the reflectivity of the film-reflective surface system is ~0.6); in the short-wave band (λ<760nm), the perovskite film has strong absorption, and the light reaching the reflective surface through the film and the substrate is attenuated more, so the copper reflective surface plays a smaller role. Therefore, in the short-wave band, as the wavelength decreases, the reflectivity of the film-reflecting surface system quickly approaches 0.

[0064] The reflection spectrum of the film-reflecting surface system measured by the single-side single reflection method ( Figure 3 Based on the dashed line in (a), the light intensity transmittance formula can be used to directly calculate the film transmittance spectrum, such as Figure 3 (a) is shown by the solid line. The film transmission spectrum measured by the transmission spectrophotometer is shown in Figure 3 As shown by the dashed line in (a). By comparison, it can be seen that the film transmission spectrum obtained by the method of the present invention is consistent with the film transmission spectrum measured by the transmission spectrophotometer. In this embodiment, the similarity of the transmission spectra obtained by the two measurement methods is calculated by the spectral angle matching method (SAM) to be 2.67°. Based on the obtained film transmission spectrum, the absorbance of the film can be calculated by log(1 / T).

[0065] In order to further verify the test accuracy of the present invention, MAPbI3 perovskite films with thicknesses of h = 190nm and h = 130nm were also measured. The experimental results are as follows: Figure 3 (b) and (c). By comparing the transmission spectrum measured by the single-side single reflection method (solid line) with the transmission spectrum measured by the transmission spectrophotometer (lined line), the transmission spectra of films of different thicknesses measured by these two methods are basically consistent, and their spectral similarities are 1.82° and 1.39°, respectively. Figure 1 Similar results can be obtained for other reflective surfaces in the film. The single-reflection device only needs to collect the reflectivity of the film-reflective surface system once to measure the transmission spectrum of the film, and the collection time is less than or equal to 200ms. The transmission spectrophotometer of the transmission device needs to rotate the grating to measure the transmission spectrum of the film, and the collection time takes about 5 minutes. Therefore, the use of a single-side single-reflection device can measure the transmittance of the film more quickly and accurately.

[0066] The present invention is integrated with film-making equipment such as a spin coater, a heating annealing table or a coater:

[0067] Many thin films are prepared using a spin coater and a coating machine. The device proposed in the present invention can be directly integrated with the spin coater without any modification to the spin coater. Figure 4 As shown in (a), it is only necessary to fix the sample stage with a rotationally symmetric reflective surface on the turntable of the spin coater. Heating annealing is a common method to improve the quality and performance of thin films, and is widely used in the preparation of various thin film materials, especially in the fields of semiconductors, optoelectronic materials, etc. The heating annealing process can reduce defects in the film, thereby improving the crystallinity of the film and enhancing the electronic and optical properties of the film. The present invention proposes to directly integrate the single-sided single reflection device with the heating annealing stage, as shown in the schematic diagram Figure 4 (b) As shown. Similarly, the integration process does not require any modification to the heating annealing table. Just place the sample table with the reflective surface on the heating table. The single-sided single-reflection device can also be integrated with the coater. It should be noted that only two integration examples are shown here, the spin coater and the heating annealing table and Figure 1 The other curved surfaces in the device can be integrated separately. Integrating the device of the present invention directly with film-making equipment such as a spin coater, a heating annealing table or a coating machine can realize real-time in-situ spectral measurement of the thin film growth process.

[0068] The following is an experiment in which the device of the present invention is directly integrated with a heating annealing table. A sample table with a reflective surface is fixed on the heating annealing table. Figure 2 (b) is made of copper. Since copper has a high thermal conductivity of 413W / (mK), the results of annealing the film on a copper sample table and directly placing the film on the annealing table are consistent.

[0069] First, set the heating annealing table to the required experimental temperature (100°C) in advance. After the heating annealing table is heated, use a thermocouple thermometer to measure the temperature of the sample table. The temperature is 100°C, which is the same as the temperature of the heating annealing table, thanks to the excellent thermal conductivity of copper. In the experiment, a MAPbI3 perovskite ink with a concentration of 1.25M was spin-coated on a glass substrate treated with oxygen plasma using a spin coater. After the spin coater is completed, the sample is immediately transferred to a low-pressure auxiliary device to wait for the MAPbI3 perovskite crystal nucleus to be fully precipitated. Then, place the thin film sample in a Figure 4 (a) is shown on the copper sample stage.

[0070] Figure 5In the figure, (a) shows the transmittance spectrum change of the film prepared with 1.25M perovskite ink when the annealing time is 0-20s (left) and 0-600s (right); (b) shows the transmittance spectrum change of the film prepared with 1M perovskite ink when the annealing time is 0-20s (left) and 0-600s (right); (c) shows the transmittance spectrum change of the film prepared with 0.75M perovskite ink when the annealing time is 0-20s (left) and 0-600s (right).

[0071] According to the measurement method of the present invention, the reflection spectrum R(λ) of the film-reflecting surface system can be continuously collected during the film annealing process, and then the relationship between the transmission spectrum T(λ) of the film during the annealing process and time can be directly calculated, such as Figure 5 As shown in (a). During the annealing process of MAPbI3 film from 0 to 4 s, the band edge of the transmission spectrum of the film obviously red-shifts (from 650nm to 750nm). This phenomenon indicates that during this period of time, the perovskite crystal nucleus grows to form a film; during the period of 4 to 9 s, the band edge of the film transmission spectrum slowly red-shifts from 750nm to 760nm (the characteristic transmission band edge of MAPbI3), indicating that during this period of time, the organic solvent of the film is continuously volatilized under the action of heating annealing, and the main component of the film is converted into MAPbI3 perovskite; within the time range of 10 to 600 s (heating annealing is completed), the band edge of the film transmission spectrum remains unchanged (760nm).

[0072] The integrated device was used to measure the transmittance spectra of films prepared with perovskite inks with concentrations of 1 M and 0.75 M during heating and annealing in real time. The measurement results are shown in Figure 5 As shown in (b) and (c). For the film prepared with the perovskite ink with a concentration of 1M, the band edge of the film transmittance spectrum slowly red-shifts from 650nm to 760nm within 0-8s; within the time range of 9-600s (heating annealing is completed), the band edge of the film transmittance spectrum remains unchanged (760nm). For the film prepared with the perovskite ink with a concentration of 0.75M, the band edge of the film transmittance spectrum slowly red-shifts to 760nm within 0-8s; within the time range of 9-600s (heating annealing is completed), the band edge of the film transmittance spectrum remains unchanged (760nm). The band edge of the transmittance spectrum of the film prepared with the perovskite ink with a concentration of 1.25M ( Figure 5 a) It is not until annealing for 10s that the film is stably formed, and the speed of the band edge of the transmission spectrum is slower than that of the film prepared by the perovskite ink with a concentration of 1M and 0.75M. This is because the increase in the concentration of the perovskite ink increases the thickness of the film. In addition, Figure 5It can be seen intuitively that after the band edge of the transmission spectrum of the perovskite film of different thickness is formed, its transmission spectrum will not change substantially until the entire heating annealing process is completed. The above experimental results fully demonstrate that the single-sided single reflection device proposed by the present invention is successfully integrated with the heating annealing station.

[0073] The present invention proposes a real-time in-situ spectral integrated measurement method based on unilateral single reflection, and measures the transmission spectra of perovskite films of different thicknesses according to this method. In the method of measuring the transmittance of a thin film by the unilateral single reflection method, in order not to collect the reflected light on the upper and lower surfaces of the film, the incident light is obliquely incident on the surface of the film; in order to effectively utilize the transmitted light, the present invention proposes to set a flat or curved reflective surface under the substrate so that the transmitted light is vertically incident on the reflective surface and then returns along the original path to be collected by an optical fiber or a lens. The unilateral single reflection measurement method does not require the complex refractive index of the film material and the thickness of the film to be known in advance, and is suitable for real-time in-situ measurement during the growth of the film. In addition, since the incident light and the light returned from the original path of the reflective surface are collinear and are on the same side of the sample, the entire measurement system becomes very compact and easy to integrate. The experimental results show that the transmittance spectra of perovskite films of different thicknesses measured by the measurement method proposed by the present invention are in good agreement with the results measured by a transmission spectrophotometer, and the spectral similarity obtained by the two measurement methods is better than 2.7°. Compared with traditional transmission methods (such as spectrophotometers), the single reflection method has the advantages of small size, easy integration, and fast measurement speed.

[0074] Furthermore, the present invention integrates the single-side single reflection measurement device with the film-making equipment, such as Figure 6 As shown in the figure, the real-time in-situ monitoring of the changes in the transmission spectrum of the thin film growth process was successfully achieved. This integrated device realizes the function of real-time in-situ measurement of the thin film growth process, providing an effective and feasible solution for studying the dynamic process of the film-making process, as well as understanding and optimizing the device function.

[0075] Finally, it should be noted that the purpose of publishing the embodiments is to help further understand the present invention, but those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A real-time in-situ spectral integrated measurement method based on single-side single reflection, characterized in that: The measuring method comprises the following steps: 1) Build a real-time in-situ spectral integrated measurement device: The film to be measured is placed on a transparent substrate, with the environment above the film; the substrate transmittance T s ≥5%; The substrate is placed on the reflection surface to form a film-reflection surface system, and the reflection surface is placed on the sample stage; the reflection surface is a plane reflection surface or a curved reflection surface; when the reflection surface is a plane reflection surface, the angle between the surface of the film to be measured and the plane where the reflection surface is located is the tilt angle β; when the reflection surface is a curved reflection surface, the angle between the surface of the film to be measured and the tangent plane of the reflection point is the tilt angle β, β>0; An incident light path and an outgoing light path are arranged above the film; a light source is coupled to the incident light path, an end of the outgoing light path is coupled to a detector or a spectrometer, and the detector or the spectrometer is connected to a computer; 2) Beam propagation: Parallel beam: The light emitted by the light source is collimated and becomes a parallel beam, which is incident on the film through the incident light path. The light intensity of the beam is I0. The incident light is incident on the surface of the film at an incident angle α, α=β>0, and part of the light is reflected into the environment. The other part of the light is refracted by the film and the substrate and vertically incident on the reflecting surface, and then vertically reflected by the reflecting surface and returned along the original path, and finally refracted from the upper surface of the film into the environment. Divergent beam: The light emitted by the light source is not collimated to form a divergent beam that is incident on the film through the incident light path. The light intensity of the beam is I0, and the divergence angle is γ=arcsin(NA), where NA is the numerical aperture of the optical fiber or lens in the output light path; the central light of the divergent beam, i.e., the principal light, is incident on the surface of the film at an incident angle α, where α>arcsin(NA) and α≥β>0, and a portion of the light is reflected into the environment. The portion of the light in the divergent beam that is perpendicular to the reflection surface, i.e., the light with an angle of (α-β) with the principal light, is refracted by the film and the substrate and vertically incident on the reflection surface, and then vertically reflected by the reflection surface and returns along the original path, and finally refracted from the upper surface of the film into the environment; 3) Beam reception: The light beam refracted from the upper surface of the film-reflecting surface system to the environment is received by a detector or a spectrometer through the outgoing light path, and the light intensity I of the light beam refracted from the upper surface of the film-reflecting surface system to the environment is obtained. R ; 4) Light intensity formula: The intensity of the light beam refracted from the upper surface of the film-reflector system to the environment is I R satisfy: I R =I0×T×T s ×R m ×T s ×T Where T is the light intensity transmittance of the film, T s is the light intensity transmittance of the substrate, R m is the light intensity reflectivity of the reflecting surface; 5) Reflectivity formula: According to the light intensity formula in step 4), the reflectivity R of the film-reflecting surface system is obtained as: 6) Get the transmittance: According to the known light intensity transmittance T of the substrate s and the light intensity reflectivity R of the reflecting surface m , using the reflectivity formula in step 5), the light intensity transmittance T of the film is further obtained: Therefore, the light intensity transmittance T of the film can be directly calculated by measuring the reflectivity R of the film-reflecting surface system without knowing the complex refractive index of the film material and the thickness of the film in advance. This is suitable for real-time in-situ measurement during the film growth process.

2. The measuring method according to claim 1, characterized in that: In step 1), the light source uses a multi-wavelength light source to directly measure the film transmittance spectrum; or, the light source uses a monochromatic light source to measure the film transmittance at one wavelength.

3. The measuring method according to claim 1, characterized in that: In step 1), the reflective surface adopts a reflective mirror or a reflective film.

4. The measuring method according to claim 1, characterized in that: In step 1), the sample stage adopts a bracket, a support frame, a support shell or a block support.

5. The measuring method according to claim 1, characterized in that: The incident light path and the outgoing light path adopt an optical fiber transmission system or a free space transmission system; when the optical fiber transmission system is adopted, the incident light path adopts an incident optical fiber, and the outgoing light path adopts an outgoing optical fiber; When a free space transmission system is used, the first lens is used for the incident light path and the second lens is used for the outgoing light path. In the incident light path, the incident light is collimated by the first lens and then incident on the upper surface of the film through the beam splitter. In the outgoing light path, the outgoing light is collected by the second lens after passing through the beam splitter and coupled to a detector or a spectrometer.

6. The measuring method according to claim 1, characterized in that: The real-time in-situ spectral integrated measurement device is integrated with the film-making equipment to realize real-time in-situ monitoring of the transmission spectrum of the thin film growth process.

7. A real-time in-situ spectral integrated measurement device based on single-side single reflection, characterized in that: The real-time in-situ spectral integrated measurement device comprises: a substrate, a reflection surface, a sample stage, a light source, an incident light path, an outgoing light path, a detector or a spectrometer, and a computer; The film to be measured is placed on a transparent substrate, with the environment above the film. The substrate transmittance T s ≥5%; The substrate is placed on the reflective surface to form a film-reflective surface system, and the reflective surface is placed on the sample stage; the reflective surface is a plane reflective surface or a curved reflective surface; when the reflective surface is a plane reflective surface, the angle between the film surface to be measured and the plane where the reflective surface is located is the tilt angle β; when the reflective surface is a curved reflective surface, the angle between the film surface to be measured and the tangent plane of the reflection point is the tilt angle β, β>0; An incident light path and an outgoing light path are arranged on the film; a light source is coupled to the incident light path, an end of the outgoing light path is coupled to a detector or a spectrometer, and the detector or the spectrometer is connected to a computer; When the light emitted by the light source is collimated and becomes a parallel beam, it is incident on the film through the incident light path; the incident light is incident on the surface of the film at an incident angle α, α=β>0, part of the light is reflected into the environment, and the other part of the light is incident on the reflecting surface after being refracted by the film and the substrate, and then is vertically reflected by the reflecting surface and returns along the original path, and finally refracted from the upper surface of the film into the environment; or, the light emitted by the light source is not collimated to form a divergent light beam, which is incident on the film through the incident light path, and the divergence angle of the light beam is γ=arcsin(NA), NA is the numerical aperture of the optical fiber or lens of the output light path; the principal ray of the divergent light beam, that is, the middle ray of the divergent light beam, is incident on the surface of the film at an incident angle α, α>arcsin(NA) and α≥β>0, part of the light is reflected into the environment, and the part of the light in the divergent light beam that is perpendicular to the reflecting surface, that is, the light with an angle of (α-β) with the principal ray, is refracted by the film and the substrate and vertically incident on the reflecting surface, and then is vertically reflected by the reflecting surface and returns along the original path, and finally refracted from the upper surface of the film into the environment; A light beam refracted from the upper surface of the film-reflecting surface system into the environment is received by a detector or a spectrometer via an outgoing light path to obtain the light intensity of the light beam refracted from the upper surface of the film-reflecting surface system into the environment; the reflectivity of the film-reflecting surface system is obtained based on the light intensity; the light intensity transmittance of the film is obtained based on the known light intensity transmittance of the substrate and the light intensity reflectivity of the reflecting surface, as well as the reflectivity of the film-reflecting surface system.

8. The real-time in-situ spectral integrated measurement device according to claim 7, characterized in that: The real-time in-situ spectral integrated measurement device is integrated with the film-making equipment to achieve real-time in-situ monitoring of the transmission spectrum of the thin film growth process.

9. The real-time in-situ spectral integrated measurement device according to claim 7, characterized in that: The reflective surface is a reflective mirror or a reflective film.

10. The real-time in-situ spectral integrated measurement device according to claim 7, characterized in that: The incident light path and the outgoing light path adopt an optical fiber transmission system or a free space transmission system; when the optical fiber transmission system is adopted, the incident light path adopts an incident optical fiber, and the outgoing light path adopts an outgoing optical fiber; When a free space transmission system is used, the first lens is used for the incident light path and the second lens is used for the outgoing light path. In the incident light path, the incident light is collimated by the first lens and then incident on the upper surface of the film through the beam splitter. In the outgoing light path, the outgoing light is collected by the second lens after passing through the beam splitter and coupled to a detector or a spectrometer.

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