Device for positioning flow of atoms evaporated from diffusion source

Abstract

FIELD: instrument making.SUBSTANCE: invention which can be used in the scientific field and is intended for positioning a flow of atoms. A device for positioning a flux of atoms evaporated from a diffusion source of a growth chamber comprises an emitting module connected to a computer, consisting of a coupling device, a laser control device, and a laser with a wavelength in the visible spectrum, and a receiver and computing module containing a photoelectron target, converters, signal amplifiers, a multiplexer, and a microcontroller; the laser is mounted in a housing, rigidly secured in a tube with a scale, installed in an open port of the growth chamber, and the photoelectron target is installed and positioned relative to the center of the open port; the laser operates in the laser tape measure mode and determines the distance to the photoelectron target; the microcontroller determines the coordinates of the laser spot and visualizes them by means of a personal computer, the multiplexer alternately evaluates the values of the currents of the photodetectors, using the analog-to-digital input of the microcontroller.EFFECT: increase in the accuracy of positioning the atomic flow.1 cl, 3 dwg

Description

[0001] The invention can be used in the scientific field, relates to the field of instrument making and is intended for positioning a flow of atoms evaporated from a diffusion source onto a substrate.

[0002] Various types of devices for positioning moving objects relative to static objects are known in the prior art. This task is most often accomplished using the following components: an emitter, a radiation receiver, and a computer. Such devices can be used in various industries, such as agriculture, the military, science, and technology. For example, RU 54483 proposes a device for monitoring seed flow, in which the emitter is an infrared light source, the radiation receiver is a photodiode matrix, and the computer is a microcontroller unit. This device is used to determine the number of seeds and evaluate the uniformity of their distribution as they fall into the collector. These operations are performed by comparing the seed count results with the results of an analysis of the darkened silhouettes that appear on the photodiode matrix due to the interruption of the infrared light by the seeds. The described device is not intended for positioning the seed flow relative to the seed collector.

[0003] RU 2806533 describes a modular optical-electronic target comprising emitters in the form of two spatially separated light sources, radiation receivers in the form of linear arrays of phototransistors, and a computer in the form of a specialized computing device. This device allows for determining the coordinates of a bullet's impact point within the detection zone, encompassed by the intersection of the emitters' optical beams. The implementation of this task is based on recording light interruptions at the intersection of the emitters' optical beams, detected by photodetectors as their state changes from illuminated to darkened. In this device, additional intermediate components are located between the radiation receiver and the computer: comparator microcircuits and a programmable integrated logic circuit consisting of a logical OR element, a data register, and a shift register. This complicates the structure and, consequently, the operation of the device.The presented device does not describe the principle of its calibration.

[0004] RU 2848929 presents a laser-optical system for calibrating an industrial robot arm. It utilizes a laser mounted on the arm as the emitter, a digital camera as the receiver, and a specialized computing unit as the computer. This device is designed to position the arm. This is accomplished by adjusting the arm's coordinates in all three directions until the laser spot from the emitter, recorded by the digital camera on the back of the calibration screen, aligns with the center marked on the screen. This device requires complex software, as the digital camera must recognize the laser spot and match it with the screen coordinates.

[0005] RU 2563339 proposes an atomic force scanning probe microscope using quasiparticles. This device uses a laser as the emitter, a four-section photodiode as the radiation receiver, and an AFM controller as the computer. This microscope can be used to obtain 3D images of near-surface layers with nanometer resolution. This operation is accomplished by moving a cantilever across the surface being examined, modulating the position of the laser beam reflected from the cantilever's mirror surface onto the photodetector. This atomic force microscope is the most complex of the devices presented, as it has an additional component in the form of a cantilever and its movement mechanism. Given the microscope's nanometer resolution, positioning the cantilever is a complex technical and software challenge.

[0006] RU 2368856 describes a sighting device with a laser rangefinder, in which the emitters are a continuous-wave laser and a pulsed laser, the receiver is a photodetector, and the computer is the electronic system of the laser rangefinder. This device is used for two purposes: aiming an object at a target and measuring the range to that target. The first task is accomplished using a continuous-wave laser by aligning the aiming mark of the reticle with the center of the selected target, accomplished by rotating the sight. The second task is accomplished using a pulsed laser, whose radiation hits the target and, after reflection, is transmitted through the optical system to the photodetector. The electronic system of the laser rangefinder generates a signal indicating the measured range to the target and transmits it to the indicator devices.This device uses an eyepiece for positioning, and the distance to the target measured by the rangefinder is hundreds of meters, which complicates the design of the device.

[0007] The closest analogue of the proposed invention is the laser firing simulator presented in RU 2468326. This device comprises emitting channels housed in a housing whose optical axes are technologically matched. The emitting channel, simulating a shot, contains a first laser with an IR wavelength and a first shaping optical system, which are optically coupled. The second emitting channel contains a second laser with a visible wavelength and a second shaping optical system, which are optically coupled. The simulator also contains a device for activating the mode of matching the firing simulator's emission axis with the optical axis of the sight, implemented in the form of a button. The lasers are connected to a laser triggering device, which may contain an electronic trigger button and a control device (microprocessor). The housing is equipped with a device for mounting on a weapon and a mechanism for aligning the firing simulator with the axis of the weapon's sight.The laser shooting simulator is aligned using a screen (a regular target or a wall).

[0008] The device operates as follows. The firing simulator is attached to the weapon, and before the simulated firing begins, the firing simulator is aligned with the weapon's sight. Alignment of the emission axis of the emitting channel simulating the firing and the weapon's sight is accomplished using a screen mounted at a distance of typically 20-30 meters.

[0009] The shooter, looking through the sight, aims the weapon at the screen and presses the button to activate the alignment mode. The laser triggering device then fires the laser, and the emitting channel sends visible light, such as a red beam, to the screen. If the sight's reticle and the laser beam spot do not align, the shooter uses the adjustment knobs of the firing simulator to rotate the simulator relative to the weapon's sight axis, aligning the laser spot and the sight's reticle, and then turns off the laser. This prepares the firing simulator for use.

[0010] During simulated firing, the shooter aims at a wall target equipped with a photoelectric strike simulator and pulls the weapon's trigger. The laser triggering device fires the lasers, sending pulses of infrared and visible light toward the target. If the aim is correct, the infrared beam is detected by photodetectors on the target, simulating a hit.

[0011] The closest analogue considered does not provide for determining the coordinates of the laser spot on the photoelectron target and the distance from it to the laser emission point.

[0012] The technical problem solved by the proposed invention consists of the precise positioning of a flow of atoms, simulated by a laser beam, evaporated from a diffusion directed source, to a given location on a substrate, along a photoelectron target replacing it, with the determination of the coordinates of the laser spot, as well as the distance from it to the evaporation source.

[0013] The need to solve the technical problem posed is driven by the need to ensure that the flow of atoms evaporated from a directed diffusion source reaches a predetermined location on the substrate, for example, the center, to ensure uniform distribution across its surface. At the same time, the size of the atomic deposition area on the surface depends on the distance between the diffusion source and the substrate. All this allows the experimenter, in the example considered, to form nanomaterial films of uniform thickness on the substrates, which is crucial for studying their optical, electronic, and other properties and for subsequent analysis.

[0014] The proposed invention is a device for positioning a beam of atoms evaporated from a diffusion source onto a substrate. This device comprises an emitting channel in the form of a semiconductor laser with a visible wavelength, mounted in a laser tape measure, a photoelectron target in the form of a two-dimensional array of photodetectors, a computer in the form of a microcontroller with a separate multiplexer, and a computer for displaying information. The laser tape measure (the position of which is set in accordance with the position of the directed diffusion source) allows one to measure the distance from the diffusion source to the photoelectron target (the position of which corresponds to the position of the substrate), on the one hand, and on the other hand, the laser's light spot can be used to determine its coordinates using the two-dimensional array of photodetectors.The current values ​​of each photodetector are evaluated via a multiplexer through the analog-to-digital input of the microcontroller. Information from the microcontroller is transmitted via a USB interface to a personal computer, where it is visualized on the computer's screen using specialized software. The coordinate of the laser spot is determined as follows. The photocurrent values ​​of each photodetector in the two-dimensional array are compared, and the coordinate of that photodetector, which corresponds to the center of the laser spot, is determined based on the highest photocurrent value. Using a three-axis manual manipulator (for example, part of a vacuum chamber) on which the target is mounted, the position of the laser spot on the target and the distance to it can be adjusted depending on the researcher's goals and objectives.After the described positioning process, the researcher records the coordinates of the handles of the manipulator on which the photoelectron target is attached (the position of which corresponds to the position of the substrate), in order to subsequently use them in the work on forming nanomaterial films on substrates.

[0015] The difference from the closest analogue is:

[0016] 1. A microcontroller is available for determining the coordinates of the laser spot and visualizing them using a personal computer, the obtained data.

[0017] 2. A laser tape measure is available to determine the distance between the diffusion source, which it replaces, and the photoelectron target, which replaces the substrate.

[0018] 3. A multiplexer is available for sequentially evaluating the current values ​​of the photodetectors included in the photoelectronic target, using the analog-to-digital input of the microcontroller.

[0019] The invention utilizes a laser as an emission channel (replacing a diffuse directed source) with a visible wavelength, a photoelectron target (replacing the substrate) in the form of a two-dimensional array of photodetectors, and a microcontroller with a multiplexer (for determining the coordinates of the laser spot based on the comparison of photodetector currents). This allows for precise positioning of the atomic beam evaporated from the diffuse directed source to a specified location on the substrate. The use of a laser tape measure allows for the determination of the distance from the laser spot on the photoelectron target to the evaporation source.

[0020] The device is shown in the following drawings:

[0021] Fig. 1 - Structural diagram of the device for positioning the flow of atoms evaporated from a diffusion source;

[0022] Fig. 2 - 3D model of laser tape measure adapter;

[0023] Fig. 3 - 3D model (in section) of the device for positioning the flow of atoms evaporated from the diffusion source inside the growth chamber.

[0024] Fig. 1 shows the structural diagram of the device for positioning the flow of atoms evaporated from a diffusion source. In this diagram, the personal computer (PC) corresponds to number 1. The radiation module of the laser tape measure consists of the following units: coupling device (CD) - 2; laser control device (LD) - 3; laser (L) - 4. The receiver and computer module contains the following units: photoelectronic target (PT) - 5; converters (C) - 6; signal amplifiers (A) - 7; multiplexer (M) - 8; microcontroller (MC) - 9.

[0025] Fig. 2 shows a 3D model of the laser tape measure adapter. In this 3D model, the laser corresponds to number 4; the tube with a scale - 10; the cable (for connecting the PC with the growth chamber) - 11; the CF flange (for fixing the adapter to the growth chamber port) - 12; the tube clamps - 13; the laser tape measure body - 14; the laser start button (used in manual mode, without connecting to a PC) - 15.

[0026] Fig. 3 shows a 3D model (in section) of the device for positioning the flow of atoms evaporated from the diffusion source, inside the growth chamber. In this 3D model, the laser corresponds to number 4; the photoelectron target - 5; the tube with a scale - 10; the cable (for connecting the PC with the US) - 11; the CF flange (for fixing the adapter on the port of the growth chamber) - 12; the tube clamps - 13; the cable (for connecting the MC with the PC) - 16; the manipulator - 17; the growth chamber - 18.

[0027] The operating principle of the device (Fig. 1, 2, 3) is as follows.

[0028] Interface device 2 and microcontroller 9 are connected to personal computer 1 via cables 11 and 16, respectively. The signal from interface device 2 is sent to control device 3 of laser 4, which is mounted in housing 14, securely fastened in tube with scale 10. Using control device 3, upon command from personal computer 1, laser 4 of the laser tape measure's emission module is turned on. The light beam (with a wavelength in the visible spectrum, shown by the dotted line in Fig. 3) then impacts photoelectron target 5, which is part of the radiation receiver and computer module. In this case, the signals from each sensor included in the photoelectronic target 5 are sent through separate channels to the corresponding converters 6. The latter convert the photocurrent values ​​(of the corresponding sensor) into voltage values ​​(proportional to the photocurrent), which are sent to the amplifiers 7.The amplified signals are fed to the inputs of multiplexer 8. Multiplexer 8 switches the received signals alternately to the analog-to-digital input of microcontroller 9, depending on the address set by this microcontroller at the address inputs of the multiplexer. Using a program installed on personal computer 1, the degree of illumination (based on photocurrent values) of the sensors (arranged in a two-dimensional array) of photoelectronic target 5 is determined. The process of determining the coordinates of the illuminated sensor is visualized on the screen of computer 1.

[0029] The positioning of the flow of atoms evaporated from the diffusion source by this device (Fig. 1, 2 and 3) is carried out as follows:

[0030] The first step involves visually "roughly" adjusting the position of photoelectron target 5 using manipulator 17 relative to the center of the open port of growth chamber 18, onto which the laser tape measure adapter is then installed. Once the entire positioning process is complete, a diffusion source will be installed on this port, in place of the laser tape measure adapter.

[0031] The second step involves placing and securing the laser tape measure adapter to the port of growth chamber 18 such that laser 4 is located at a distance from photoelectron target 5 corresponding to the distance from the diffusion source after positioning. The position of photoelectron target 5, in turn, corresponds to the location of the substrate onto which the substance from the diffusion source is planned to be deposited. The laser tape measure is connected to personal computer 1 via cable 11, after which the remote distance measurement mode with the tape measure is started. Next, clamps 13 of tube 10 are loosened and moved toward photoelectron target 5, achieving the desired distance based on the tape measure measurement data displayed on personal computer 1. Next, tube with scale 10 is secured to flange 12 using clamps 13.

[0032] The third stage consists of determining the coordinates of the photoelectron target 5, according to the scales of the manipulator 17, provided that the beam of the laser 4 hits the center of the target 5. For this, the tape measure is turned on in the radiation mode of the laser 4. The receiver and computer module is connected by a cable 16 to the personal computer 1. The manipulator 17 of the growth chamber 18 is used to move the photoelectron target 5 relative to the beam of the laser 4. This operation is performed until the degree of illumination, determined by the program of the personal computer 1 (based on the estimate of the highest value of the photocurrent), is maximum at the sensor located in the center of the two-dimensional array of sensors of the photoelectron target 5. Then, the coordinate values ​​on the scales of the manipulator 17 are fixed, and they are subsequently used when adjusting the position of the substrate for the deposition of a substance from a diffusion source.

[0033] The technical result of using the invention is that, thanks to a device for positioning the flow of atoms evaporated from a diffusion source, this flow is precisely directed to a predetermined location on the substrate, for example, its center, and the distance between the source and the substrate is also set. This device allows the experimenter to form films of uniform thickness on substrates.

[0034] List of references:

[0035] 1. Patent No. 54483.

[0036] 2. Patent No. 2806533.

[0037] 3. Patent No. 2848929.

[0038] 4. Patent No. 2563339.

[0039] 5. Patent No. 2368856.

[0040] 6. Patent No. 2468326.

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