CN2589968Y - Multifunctional photoelectric parameter measuring device - Google Patents

Abstract

The utility model discloses a multifunctional photoelectric parameter measuring device. It solves the problems that the existing instrument cannot measure the light reflectance R under the condition of vertical incident light, and the measurement function is single. Technical solution: the light source is connected to the monochromator, a chopper is installed at the output slit of the monochromator, a half-transparent mirror M is installed at the output end of the chopper, and a focusing lens is placed in the transmitted light path, the focus is in the sample chamber; the sample A laser is installed on one side of the chamber perpendicular to the transmitted light beam, and a position-sensitive detector is installed on the other side; focusing lenses are respectively installed between the sample chamber and the laser and between the sample chamber and the position-sensitive detector, and are set on the reflected light path. a light detector; the outputs of the light detector and the position sensor are respectively connected with the input of the lock-in amplifier, and the output of the lock-in amplifier is connected with the input of the computer. Realize one machine with multiple functions. It can save a lot of equipment funds, laboratory space and human resources in maintenance and management.

Description

Multifunctional Photoelectric Parameter Measuring Device

Technical field

The utility model relates to a measuring device for optical and electrical properties of materials.

Background technique

At present, the instruments for measuring the photoelectric parameters of materials cannot measure the light reflectance R of materials under the condition of vertical incident light, and cannot detect the small amount of light absorption of semiconductor photoelectric materials, and the measurement function is single. For example, the existing spectrophotometer can only measure the transmittance and reflectance of light within a limited range; in addition, when measuring the light transmittance T and light reflectance R of thin film materials at different angles, the two are not relevant data; Especially in the case of interference, the measurement data may produce a situation of T+R≥1, which makes the light absorption appear unreasonably negative. Another example is that a photoconductive spectrometer can only measure the photoconductive parameters of materials, and its measurement function is single, so different instruments are required to measure different parameters. In this way, not only equipment funds and laboratory space are wasted, but also human resources are wasted in maintenance and management.

Utility model content

The utility model is designed to solve the above-mentioned defects, and its purpose is to provide a light reflectance R that can measure the material under the condition of vertical incident light, which integrates multiple measurements, saves laboratory space and cost, and speeds up the measurement. And a multifunctional photoelectric parameter measuring device that reduces experimental expenses.

The technical scheme of the utility model is: mainly comprising a light source, a monochromator, a chopper, a light detector, a position sensor, a lock-in amplifier, a computer, a semi-transparent mirror, a laser and a sample chamber; the light source and the monochromator Connect to the instrument, install a chopper at the output slit of the monochromator, set a half-transparent mirror M in the optical path of the output end of the chopper, and a focusing lens in the optical path of the transmitted beam, the focus is in the sample chamber; A laser is installed on one side of the sample chamber perpendicular to the transmitted light beam, and a position-sensitive detector is installed on the other side; focusing lenses are respectively installed between the sample chamber and the laser and between the sample chamber and the position-sensitive detector, and on the reflected light path A photodetector is set; the output terminals of the photodetector and the position sensor are respectively connected with the input terminals of the lock-in amplifier, and the output terminals of the lock-in amplifier are connected with the input terminals of the computer.

The beneficial effects of the utility model are: due to the addition of a half-mirror (which can split beams) in the light path, and the half-mirror forms an angle of 45° with the incident light. Therefore, the light reflectance R of the material can be measured under the condition of normal incident light. When measuring the light reflectance R of photoelectric thin film materials with interference properties, it can ensure that there is a correlation with the transmittance measured by vertically incident light, and can be used for the calculation of optical parameters, avoiding that the two are not related data, and the measurement data may be T+R≥1, unreasonable negative value of light absorption, etc.; the device can also measure the electrical and electronic parameters of materials, such as photoconductivity spectrum, photocell quantum efficiency and photothermal deflection spectrum. All in one, realizing one machine with multiple functions. In this way, a lot of equipment funds, laboratory space and human resources in maintenance and management can be saved.

Description of drawings

Fig. 1 is a schematic block diagram of the light path and structure of the utility model.

Fig. 2 is a schematic block diagram of the optical path and structure of the utility model for measuring light transmittance.

Fig. 3 is a schematic block diagram of the optical path and structure of the application of the utility model to measure the light reflectivity.

Fig. 4 is a schematic block diagram of the optical path and structure for measuring the photoconductive spectrum and photocell quantum efficiency of the utility model.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in further detail.

As shown in Figure 1, the light source adopts a combination light source, deuterium lamp, tungsten halogen lamp and its controllable power supply; the monochromator adopts a grating monochromator, and its output monochromatic wavelength is 200nm-2500nm; the optical detector adopts a vacuum thermopile, Si or P _b S light detector, the light position sensor adopts double photodiode type light position sensor, the lock-in amplifier adopts EG & G 5208, and the laser uses He-Ne laser; the light source is connected with the monochromator, and the monochromator A chopper is installed at the output slit of the chopper, a half-transparent mirror M is arranged in the optical path of the output end of the chopper, a focusing lens is arranged in the optical path of the transmitted light beam, and the focal point is in the sample chamber; A laser is installed where the transmitted light beam is perpendicular, and a position-sensitive detector is installed on the other side; focusing lenses are respectively installed between the sample chamber and the laser and between the sample chamber and the position-sensitive detector, and optical detectors are installed on the reflected light path; light detection The output terminals of the sensor and the position sensor are respectively connected with the input terminals of the lock-in amplifier, and the output terminals of the lock-in amplifier are connected with the input terminals of the computer.

The best solution of the utility model is that the half-transparent mirror M forms an angle of 45° with the light beam in the chopper output end optical path.

1. Measuring light transmittance: As shown in Figure 2, using the light source, monochromator, chopper, half mirror M, light detector, lock-in amplifier, and computer combination in the device, the material can be measured The light transmittance of the sample.

When measuring, without placing the sample under test, first, scan and measure the light intensity of each wavelength. The output light of the monochromator is chopped by the chopper and reflected by the half mirror M, and the light will follow the direction of the arrow. After entering the optical detector, the output signal is amplified by the lock-in amplifier, and the data is stored in the computer; then, the measured sample is placed in front of the detector incident window, and the same measurement is performed, and the two measurement results are normalized in the computer , the relationship between the transmittance of the sample and the wavelength can be obtained.

2. Measure light reflectance: as shown in Figure 3, use the light source in this device, monochromator, chopper, half mirror M, light detector, lock-in amplifier, computer and sample room combination, can Measure the light reflectance of material samples, but the difference is that the half mirror should be rotated 90° to ensure that the sample surface is perpendicular to the incident light during measurement.

When measuring, place the standard reflector at a position perpendicular to the beam passing through the half-mirror M and perform wavelength scanning, and the computer records the light intensity signals of different wavelengths; replace the standard reflector with the sample to be measured, and perform wavelength scanning again. Scan and record the light intensity data of the sample; normalize the sample data with the data of the standard mirror to obtain the light vertical reflectance R of the sample.

If there are two (or more) interference peaks (valleys) in the curve of reflectivity versus wavelength, the thickness d of the film material can be calculated from the wavelength data of the corresponding interference peaks (valleys) and the refractive index of the sample using the light wave interference formula .

The absorption coefficient α(λ) can be calculated from the light reflectance R(λ), the light transmittance T(λ), and the thickness d, and the optical band gap Eg can be further obtained.

3. Measure (constant) photoconductive spectrum: as shown in Figure 4, use medium light source, monochromator, chopper, light detector, half mirror, sample chamber, lock-in amplifier, computer in this device The combination can measure (constant) photoconductive spectrum; the difference of this combination is that the output terminal of the computer is connected to the light source, and the light output of the light source can be controlled to keep the photocurrent during the measurement process constant, which is the constant photoconductive spectrum. Therefore, there are the following requirements for photoconductive spectroscopy measurement:

(1) Sample: For thin film samples, it is required to make coplanar electrodes on the material, and the light area is between the two electrodes. The electrodes can be drawn out by bonding wires with silver paste, or contacting with spring sheets. (2) Circuit connection: connect the voltage source, the current input terminal of the lock-in amplifier, and the sample electrode in series to form a loop. (3) Sample placement: The sample is placed in the sample chamber, so that the monochromatic light can fully illuminate the area between the two measuring electrodes of the sample, and ensure that the sample will not be disturbed by external light.

Measurement: use the light passing through the half-mirror M to excite the photocurrent of the sample, the lock-in amplifier 1 amplifies the photocurrent and then input it to the computer; Amplifier 2 is amplified and input to the computer. After the monochromator scans each wavelength once, the computer records the light intensity value and photocurrent value at each wavelength.

Calculation: The computer converts the photocurrent value into a photoconductive value, and then normalizes the light intensity value to obtain the photoconductive spectral response curve σ(λ), that is, the photoconductive spectrum.

4. Measuring the quantum efficiency: the quantum efficiency of the photovoltaic cell can also be measured with the device shown in Figure 4, the difference is that it does not need an external power supply. Place the photocell to be tested in the sample chamber, use the light passing through the half-mirror M to excite the photocurrent of the photocell, the lock-in amplifier 1 amplifies the photocurrent and input it to the computer; the photodetector receives the light from the half-mirror M The reflected light intensity signal is amplified by the lock-in amplifier 2 and then input to the computer. After the monochromator scans each wavelength once, the computer records the light intensity value and the photocurrent value of the photocell at each wavelength.

The computer converts the light intensity value into the number of incident photons corresponding to each wavelength (unit time), and converts the photocurrent into the number of photogenerated carriers generated per unit time; the quantum efficiency can be obtained by comparing the two, which is a number less than 1 .

5. Measuring the photothermal deflection spectrum: the whole combination of Fig. 1 is a schematic block diagram of the structure of the measurement photothermal deflection spectrum. The half mirror M divides the monochromatic light into two parts, the part reflected to the photodetector is used to measure the energy of the light, the transmitted part is used to excite the photothermal effect of the measured material, and the laser and position sensitive device are used to measure the light energy. thermal deflection.

(1) The sample is placed vertically in a transparent quartz box in the sample chamber. The monochromatic light is vertically focused and irradiated on the sample surface. Measuring working fluid (usually carbon tetrachloride).

(2) Turn on the laser, and adjust the position of the position sensor (PSD) when the sample is not irradiated by monochromatic light (usually the PSD is two photodiodes with a small gap), when the detection laser beam hits the two photodiodes When the irradiation is equal, the position sensor PDS output is zero.

(3) Irradiate the surface of the sample with the light that passes through the half-mirror M, and the heat generated by the sample absorbs the light, so that a temperature gradient field centered on the irradiation focus is generated in the liquid on the surface of the sample, and the increase of the local liquid temperature makes it The light's refractive index changes, forming a "liquid lens" through which the measuring laser beam is deflected. The deflection distance increases as the light beam advances (geometric ratio), and the position sensor PSD detects the deflection amount, which is amplified by the lock-in amplifier 1 and input to the computer; the light detector receives the light intensity signal reflected by the half-transparent mirror, Amplified by the lock-in amplifier 2, and input the data into the computer.

The deflection of the measuring beam actually reflects the light absorption of the sample. After normalizing the light intensity, the characteristics of the light absorption of the sample at different wavelengths are obtained. Due to its high sensitivity, it can be used to detect extremely small light absorption coefficient α.

Claims (2)

1. multifunctional light electrical parameter measuring device, its feature comprise that mainly light source, monochromator, chopper, photo-detector, position sensor, lock-in amplifier, computing machine, laser instrument and sample chamber constitute; Light source links to each other with monochromator, at the output slit place of monochromator chopper is installed, and a semi-transparent semi-reflecting lens M is set in the light path of chopper output terminal, and a condenser lens is arranged in the light path of transmitted light beam, and focus is in the sample chamber; In a side of sample chamber and with the perpendicular place of transmitted light beam laser instrument, opposite side installation site sensing detector are installed; Be separately installed with condenser lens between sample chamber and the laser instrument and between sample chamber and the Position-Sensitive Detector, photo-detector is set on reflected light path; The output terminal of photo-detector and position sensor links to each other with the input end of lock-in amplifier respectively, and the output terminal of lock-in amplifier links to each other with input end and computer.

2. according to the multifunctional light electrical parameter measuring device described in the claim 1, it is characterized in that semi-transparent semi-reflecting lens and incident light angle at 45.

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