Lighting set for Hall effect measuring devices and photo-Hall measuring devices

Abstract

Lighting set for Hall effect measuring instruments, at least comprehensive - an LED or LD (6, 6', 6''), - a holder (1, 1', 1'') for the LED or LD (6, 6', 6''), - a connecting means (2) for connecting the holder (1, 1', 1'') to the Hall effect measuring device and wherein - at least the LED or LD holders (1, 1', 1'') are made of printable material.

Description

Description

[0001] The present invention relates to an illumination set for Hall effect measuring devices and a photo-Hall measuring device as used for the characterization of certain electrical properties of materials.

[0002] In photoHall measurements, the materials under investigation are examined not only in the dark but also under illumination. The additional illumination causes changes in the Hall effect voltage and conductivity, which are measured in the material or sample being characterized.

[0003] For the purposes of the invention, light covers the wavelength range from 10–1800 nm, from the UV range through visible light to the infrared range. PhotoHall measurements are particularly important for semiconducting and semi-insulating materials used in photovoltaics. An example of a photoHall measuring device is given in WO 2020 / 208443 A1. Measurements of the photoHall effect can generally be performed using an additional light source that illuminates the material under investigation or an object in a standard Hall effect measuring device. As shown, for example, in WO 2020 / 208443 A1, the illumination of the sample can be very complex. Another example of a photoHall measurement setup is given by I. Eisele and L. Kevan (Double Modulation Method for Hall Effect Measurements on Photoconducting Materials, Review of Scientific Instruments, Vol. 43, 1972, p.189-194), in which the sample illumination is provided through a through-hole in one of the measuring device's magnets. US 11 585 871 B1 also discloses a photo-Hall measuring device. In the measuring device, the illumination is realized by the arrangement of a xenon lamp or a laser.

[0004] A Hall-effect measuring device of this type typically consists of at least one arrangement of a sample near a magnetic field created by at least one magnet, and an instrument for measuring a voltage generated in the sample by the magnetic field and an electric current applied by the power source. Additionally, cooling and heating means for the sample and a signal processing unit are usually present.

[0005] The object to be achieved by the invention is to provide an illumination for samples in Hall effect measuring devices which is inexpensive and applicable in any standard Hall effect measuring device in order to obtain at least information about the concentration, the mobilities, the lifetime, the diffusion coefficient and the diffusion length of the charge carriers by means of photo-Hall effect measurements.

[0006] The problem is solved by the features of claims 1 and 4. Advantageous embodiments are specified in the dependent claims.

[0007] Researchers at the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH recently demonstrated that, with the help of a specific algorithm, information about various charge carriers can be obtained through photo-Hall effect measurements. The resulting method is disclosed and claimed in EP 4 465 067 A1. This method not only provides a method for distinguishing charge carrier properties, but can also be performed using a light source with lower light intensity, particularly compared to commonly used lasers, such as LEDs (light-emitting diodes).

[0008] Based on this advantage, we claim an illumination kit for Hall effect meters, where an LED or a laser diode (LD) is part of the kit as the light source. LEDs and LDs share the property of being diode-based light sources, with both benefiting from the possibility of miniaturization, the ability to provide different wavelengths, and variable light intensity. The LED or LD must be selected with regard to the intended Hall effect measurement. Any wavelength, intensity, size, or other parameters of the LED or LD that need to be adapted are possible. The LED or LD can be provided with a metal plate that dissipates the operating heat of the LED or LD, either as part of the kit or as part of the LED or LD itself. Such a metal plate is placed in close contact with the LED or LD on its back.An LED or LD is usually supplied on a holder, and often more than one LED or LD is arranged for certain effects, such as color management and others, whereby each such holder can be referred to as an LED or LD chip. Within the scope of the invention, it is essential that the light source is provided by the use of LED or LD technology. The kit further comprises a holder for the LED or LD or the corresponding chips. The holder can also be referred to as a holder. The holder consists of at least a base and a frame for the LED or LD or the corresponding chips. The base is provided by at least one web. The base is further provided with a connecting means, for example a fastening, such as such e.g.by a clamp, a flange, a clip, a snap closure or the like, and possibly also by an adhesive with which the set is connected to a Hall effect measuring device. Preferably, the holder comprises a frame, as is the case in one embodiment of the invention, wherein the frame forms a frame for the LED or LD or the chips by enclosing the LED or LD or the chips from at least two sides. Further preferably, the frame is designed with a size and shape corresponding to the LED or LD or corresponding chips to be held (positive fit), as is the case in another embodiment of the invention. In addition, a clamping device for the LED or LD or the corresponding chips is part of the set, as is the case in a third embodiment of the invention. The clamping device is provided, for example, by an elastic band or is, for example,formed together with the holder, whereby in the latter case the clamping device does not necessarily have to be elastic.

[0009] The lighting set is intended to be arranged on a Hall-effect meter to form a photo-Hall meter. In this context, a connecting means for effectively connecting the lighting set to a Hall-effect meter is part of the set. As part of the lighting set, this connecting means can be provided by being arranged on the Hall-effect meter itself, wherein the holder, together with the LED or LD or chips and any other parts of the set, is operatively connected (engaged / connected) to the connecting means. In a very simple embodiment, this connecting means can be an adhesive or similar. In a more sophisticated embodiment, the connecting means is provided by a reversible connection of the holder to the Hall-effect meter, such as by a clamp, an operative connection of positive parts, a suspension, or the like.

[0010] One of the advantages of the invention is that the holder and the clamping device as well as optionally the connecting means can be made of printable material, in particular of polymers and resins, such as high density polyethylene (HDPE), high impact polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), thermoplastic elastomers (TPE), thermoplastic polyurethane (TPU), polylactic acid (PLA), glycol modified version of polyethylene terephthalate, polyamide, carbon fiber filaments, acrylstyrene acrylonitrile, polycarbonate (PC), polypropylene, metal-filled filaments, wood-based filaments, polyvinyl alcohol, polyacrylate materials (e.g. VisiJet®, 3D Systems, Inc.) acrylate, epoxy resins, fluorocarbons, phenolic resins, amides, esters, imides, styrene, (poly)sulfides, urethanes, vinyls, silicones, xylylene (incl. parylene), UV-curable parylene, UV-curable dimethylsiloxanes and carbamate / methacrylate-based compounds.Among the acrylates, multifunctional acrylate monomers such as pentaerythritol tetraacrylate and pentaerythritol triacrylate are particularly noteworthy. An example of an epoxy resin is bisphenol A novolac with a group functionality of 8. The illumination kit can thus be easily adapted to any type of Hall-effect measuring device under consideration, as well as to any type of LED or LD or corresponding chip.

[0011] A photoHall measuring device can be constructed in a method comprising the steps of a) providing a Hall-effect measuring device and b) arranging an LED or LD or corresponding chip on the device such that a sample to be measured with the photoHall measuring device is illuminated when the LED or LD or the chip is switched on. The specified illumination set for Hall-effect measuring devices makes it easier to construct a photoHall measuring device, wherein the method comprises at least the steps of a) providing a Hall-effect measuring device and b) arranging an illumination set for Hall-effect measuring devices, as described above, on the provided Hall-effect measuring device such that a sample arranged in the Hall-effect measuring device is illuminated by the LED or LD or corresponding chips when the LEDs or LDs are switched on.

[0012] A photo-Hall measuring device comprising a Hall effect measuring device and an illumination set for Hall effect measuring devices as described above is additionally provided by the inventive idea.

[0013] The advantages of the inventive idea are the inexpensive and easy-to-build solutions for providing a photo-Hall measuring device, which can be easily adapted in every respect and the thus enabled implementation of a method for separately determining relevant coefficients (such as conductivity, mobility, etc.) for majority and minority charge carriers as a function of the illuminance, as disclosed in EP 4 465 067 A1. Examples

[0014] The invention is explained in more detail using three examples of illumination sets for Hall-effect measuring devices according to the invention, for one and the same Hall-effect measuring device and three different LED types, as well as five figures. The LED types or LED chips are also representative of corresponding LDs or LD chips, since their use does not make any difference for the implementation of the invention, as the LDs or LD chips are designed in a comparable manner.

[0015] The figures show: Fig. 1: Schematic representation of a lighting set for Hall effect measuring devices according to the invention for a first LED type, realized by an LED chip. Fig. 2: Schematic representation of an illumination set for Hall effect measuring devices according to the invention for a second type of LED, realized by an LED chip. Fig. 3: Schematic representation of an illumination set for Hall effect measuring devices according to the invention for a third type of LED, realized by an LED chip. Fig. 4: Schematic representation of a photo-Hall measuring device according to the invention. Fig. 5 Measurement of the photo-Hall effect (conductivity and Hall effect coefficient as a function of the generation rate) for a silicon sample using a measuring device according to Fig. 4.

[0016] In Fig. 1 a) - c) shows the holder 1 and a connecting means 2 (not all parts of which are visible, which functions as a plug connection by snapping into a Hall effect meter) of an inventive lighting set for Hall effect meters, which is adapted for an LED chip 6 with a rectangular shape, as can be found, for example, in LED chips for white light (here realized by arranging six small white LEDs). The holder 1 consists of a base 3 and a frame 4 for the LED chip 6, which cooperates with an interacting clamping device 5, the latter being in Fig. 1 c). The LED chip 6 is in Fig. 1 b) shown from the front, while in Fig. 1 c), in which it is inserted into the set, is shown from behind. The lighting set, which consists of, among other things, the holder 1 and the clamping device 4, has a size of 3.72 cm in its longest dimension in this example, which also applies to the other examples. In this example, as in all other examples, the holder 1 and the connecting means 2 as well as the clamping device 4 are manufactured by 3D printing and are made of UV-curable plastic. The intensity of the light supplied by the LED chip 6 is controlled by the power source 101 ( Fig. 4). The electrical connection of the LED chip 6 to the power source 101 is established by an electrical connection between the LED contact 8 (in Fig. 2 8' and in Fig. 3 8") and the Hall effect sensor 103 ( Fig. 4) with conductor tracks leading to the power source 101. To ensure a positive connection for establishing the electrical connection with the contacts 8, 8', 8" of the chips, special recesses 7 (in Fig. 2 7' and in Fig. 3 7'', each indicated by dashed circles). The example in Fig. 2 a) - c) shows a holder 1' consisting of a base 3' and a frame 4' together with a clamping device 5' (shown in Fig. 2 c)), and a connecting means 2 of an illumination set for Hall effect measuring devices, which is adapted for a flat LED chip 6' with a round shape, such as is found in LEDs for monochromatic light. The LED chip 6' is in Fig. shown from the front, while in Fig. , connected to the set and shown from behind. A final example can be found in Fig. 3. The figure shows a holder 1'', which consists of a base 3'' and a frame 4'' together with a clamping device 5'' (shown in Fig. 3 c)), and a connecting means 2 of an illumination set for Hall effect measuring devices, which is adapted for a larger 6" LED chip with a rectangular shape, such as is found, for example, in LEDs for UV light. The 6" LED chip is in Fig. 3 b) shown from the front, while in Fig. 3 c) is connected to the set and is shown from behind. All examples shown include enclosures for mounting specific LEDs or LED chips 6, 6', 6'', which reflect the possible shapes and sizes of such LEDs or LED chips or LED chips that can possibly be mounted with the set. The LED chips 6, 6', 6'' each comprise at least one LED arranged on a holder and provided with all the connections required for their operation. All examples shown in Fig. 1 to Fig. 3 show the same connecting means 2, as they are all adapted to the same Hall effect measuring device. In Fig. 4 is the illumination set according to the invention for Hall effect measuring devices as described in Fig. 3 is mounted on a Hall-effect measuring device 100, so that this forms a photo-Hall measuring device. The photo-Hall measuring device 100 comprises, in addition to the set according to the invention, a connection to the power sources and the voltmeter 101, a shield 102, which can be part of a cryostat, for example, a Hall-effect card (sensor) 103, a magnet 104 and, opposite this magnet 104, an electromagnet 105, which is equipped with a Gaussian probe 106 and a connection 110 to an AC or DC power source, the lighting set 1'' according to Fig. 3 (not all parts of the set are visible in this view) together with a 6" LED chip. A sample 107 to be measured is also shown. In Fig. 5 are the results of a measurement of the conductivity (a)) and the Hall coefficient (b)) as a function of the generation rate of the charge carriers, which in turn varies as a function of the illuminance (here up to 1 solar constant), on a sample of p-silicon (p-Si) with the photo-Hall measuring device 100 according to Fig. 4 shown.

Claims

[1] Lighting set for Hall effect measuring instruments at least comprehensive - one LED or LD (6, 6', 6''), - a holder (1, 1', 1'') for the LED or LD (6, 6', 6''), - a connecting means (2) for connecting the holder (1, 1', 1'') to the Hall effect measuring device and wherein - at least the LED or LD holders (1, 1', 1'') are made of printable material. [2] Lighting set according to claim 1, characterized by that the holder (1, 1', 1'') has a frame (4, 4', 4'') for the LED or LD (6, 6', 6'') to be accommodated, with a size and shape corresponding to the LED or LD (6, 6', 6'') to be accommodated. [3] Lighting set according to claim 1 or 2, characterized by that the set additionally includes a clamping device (5, 5', 5'') for the LED or LD (6, 6', 6'') to be held. [4] A photo-Hall measuring device comprising a Hall effect measuring device and a Hall effect measuring device illumination set according to any one of claims 1 to 3.

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