An in-situ cartridge for electron microscopy and synchrotron applications

Abstract

An in-situ cartridge comprises a substrate for holding a sample wherein said substrate comprises an electron transparent window for receiving said sample and at least one optical waveguide for illuminating said sample wherein a first edge of the at least one optical waveguide is optically couplable with a light source, wherein the at least one optical waveguide is integrated in the substrate and is extended from an edge of the substrate towards the electron transparent window. In this configuration, only the substrate carrying the sample needs to be modified. Bringing the optical waveguide in the vicinity of the sample allows for various additional light sensing techniques, as well as heating and application of electric fields.

Description

[0001] An in-situ cartridge for electron microscopy and synchrotron applications

[0002] The invention relates to the field of microscopy and spectroscopy systems, in particular to electron microscopy systems and synchrotrons.

[0003] In-situ electron microscopy and in-situ beamline (synchrotron) experiments are continuously gaining more and more momentum and enable the user visualizing a variety of samples in its native environment (gas or liquid) while applying different stimuli. The current stimuli in the market are temperature control and biasing (electric f ield / current control) along with environment control i.e. gas composition and pressure for gas phase in-situ- EM and liquid composition and pressure / f low control for liquid phase in-situ-EM.

[0004] The next stimulus that will further expand the application of in-situ research is light. Being able to illuminate the sample can enable a wide variety of applications ranging from photoelectrochemistry to phot ovolt aics investigation, photocatalysis and photobiochemistry.

[0005] Currently, to introduce light stimulation in a TEM one of the following methods is used :

[0006] - applying a light fiber illuminator inside a TEM holder;

[0007] - using a fluidic TEM holder with UV illumination;

[0008] - mounting a light fiber below a sample inside a TEM pole piece; and

[0009] - placing a parabolic mirror below a sample holder.

[0010] All the abovementioned solutions for light stimulus require heavy modifications to the Electron Microscope (e.g. TEM, SEM) and / or the Synchrotron system. It is an object of the invention to correct the shortcomings of the prior art and to provide an approach that requires minimal modifications of the TEM system and that makes the experiment more user-friendly, faster and more reliable.

[0011] It is a further object to offer the capability of various light sensing techniques that allow control over the wavelength, power and phase of the light.

[0012] These and other objects which will become apparent from the following disclosure, are provided with an in-situ cartridge for microscopy and synchrotron applications having the features of one or more of the appended claims.

[0013] In a first aspect of the invention, an in-situ cartridge for electron microscopy and synchrotron applications is provided, said cartridge comprising a substrate for holding a sample, wherein said substrate comprises an electron transparent window and at least one optical waveguide for illuminating said sample wherein a first edge of the at least one optical waveguide is optically couplable with a light source, and the at least one optical waveguide is integrated in and unitary with the substrate and is extended from an edge of the substrate towards the electron transparent window of the substrate.

[0014] Accordingly between subsequent experiments, only the cartridge needs to be replaced. One added benefit is that many different waveguide designs can be designed that can all be used in combination with the same cartridge holder

[0015] . Bringing the optical waveguide in the vicinity of the sample allows for various additional light sensing techniques, as well as still enabling in the usual way heating and application of electric biasing, while controlling the surrounding environment (e.g. liquid or gas) .

[0016] One thing and another is preferably achieved by arranging that the at least one optical waveguide is provided in a layer intrinsically linked with or on the substrate so as to arrange that the waveguide and the substrate are inseparably integrated.

[0017] The term "integrated" should be understood as this term is used in "integrated circuits" in which all or some of the circuit elements are inseparably associated through lithography so that the elements are indivisible. The waveguide is therefore inseparably integral to the substrate.

[0018] In order to provide that the waveguide can be easily coupled with a light source, the first edge of the at least one optical waveguide is flush with the edge of the substrate. Therefore, the user only needs to replace the cartridge with the samplecarrying substrate without having to deal with the no longer present optical fibers extending outside of the substrate known from the prior art. The waveguide can automatically be coupled to the light source either by direct coupling of by grating coupling as it will become clear further in this disclosure.

[0019] Advantageously, a core of the at least one optical waveguide comprises silicon nitride and is embedded in a coating comprising silicon dioxide.

[0020] More advantageously, the at least one optical waveguide is at least partially devoid of coating at or near to its first edge for optically coupling said at least one optical waveguide with a light source by grating coupling or by direct coupling. Grating coupling can be done by introducing a diffractive grating structures on top of the substrate.

[0021] Moreover, the at least one optical waveguide is provided on an upper side of the substrate between the edge of the substrate and the electron transparent window of the substrate. In this first configuration, one edge of the optical waveguide is located next to the sample and the light coming from the waveguide is perpendicular to the electron beam.

[0022] Alternatively, the at least one optical waveguide is on an upper side of the substrate and extends from a first edge of the substrate towards a second edge of the substrate wherein the core of the at least one optical waveguide comprises the electron transparent window of the substrate, wherein said core of the at least one optical waveguide is at least partially uncoated to form the electron transparent window of the substrate. In this second configuration, the optical waveguide runs under the sample that is illuminated by the evanescent field. Although the evanescent field offers lower illumination power compared to the first configuration, the evanescent field interacts with the sample and continues to propagate in the optical waveguide allowing the light to be collected and analyzed, which can enable a combination of TEM and other analysis techniques such as light spectroscopy .

[0023] Optionally, the uncoated part of the core is thinner than the coated part of the core.

[0024] In the case of in-situ TEM in fluids (liquid or gas) , the transmission electron microscopy system comprises a replaceable sealing chip which is attachable to the substrate for forming a chamber in-between said sealing chip and the substrate, wherein the sealing chip comprises:

[0025] - an electron transparent window;

[0026] - at least one channel for entering into or removing fluids from the chamber;

[0027] - at least one cavity around the electron transparent window of the sealing chip for receiving at least one gasket;

[0028] - at least one gasket in the at least one cavity, wherein said gasket is engaged with the substrate when the sealing chip is attached to the substrate. To allow for a clear electron path, the electron transparent window of the sealing chip is overlapped with the electron transparent window of the substrate when the sealing chip is attached to the substrate.

[0029] Advantageously, the transmission electron microscopy system comprises a holder with an arm for holding the cartridge with the substrate, wherein said arm comprises an optical fiber for transmitting light from a first end of said arm to a second end of said arm where the substrate is located.

[0030] More advantageously, the optical fiber is connectable to a light source or to an external optical readout device using an optical fiber connector such as Sub Miniature A. This feature enables a variety of light sensing techniques.

[0031] In an optional aspect of the invention:

[0032] - the substrate comprises silicon.

[0033] - the substrate comprises at least one metallic electrode.

[0034] - the cartridge comprises at least one spacer between the substrate and the sealing chip for defining the chamber between the substrate and the seal chip.

[0035] The invention will hereinafter be further elucidated with reference to the drawing of exemplary embodiments of an in-situ cartridge and a holder for such cartridge according to the invention that is not limiting as to the appended claims.

[0036] In the drawing:

[0037] - Figures 1 and 2 show different embodiments of the in situ cartridge of the invention in a cross-sectional side view;

[0038] - figure 3 shows a cross-sectional view of a seal chip which is usable in combination with the in situ cartridge shown in figures 1-2; figures 4 and 5 respectively show the embodiments of the in situ cartridge shown in figures 1 and 2 , each combined with the seal chip according to figure 3;

[0039] - figure 6 and 7 show different embodiments of the in situ cartridge of the invention in a first cross-sectional side view (AA' ) and a in a second cross-sectional view (BB' ) ; and

[0040] - figure 8 shows a holder according to the invention holding a cartridge according to the invention.

[0041] Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

[0042] Making first reference to figure 8, it shows a holder 14 for a cartridge 1, which cartridge has at least one substrate 2 i.e. at least one photonic chip. The holder 14 comprises at least one standard optical fiber connector (SMA) 12 where an external light source or a read-out device can be connected. The SMA connector 12 and the cartridge 1 with the at least one substrate 2 are optically connected via the standard optical fiber running through the holder' s arm 10. The optical fiber is optically coupled to the at least one substrate 2 via for instance a grating coupling or a direct coupling. The holder 14 may still contain ports, tubing and wirings for electronic and fluidic controls .

[0043] To achieve light stimulus in TEM, SEM and / or Synchrotron applications in which a cartridge 1 is used as depicted in one of figures 1 and 2, the concerning cartridge 1 is provided with an optical waveguide 4 which is unitary and integrated with a substrate 2. More specifically expressed in all embodiments the at least one optical waveguide is provided in a layer intrinsically linked with or on the substrate so as to arrange that the waveguide and the substrate are inseparable. In a first configuration shown in figure 1, the waveguide 4 extends from an edge of the substrate 2 to the electron transparent window 3.1. The substrate 2 is for instance optically coupled with the SMA connector 12 of figure 8 at the aforementioned edge via an optical fiber 11. The light can either be directly coupled to the waveguide' s 4 edge or grating coupling can be used utilizing diffractive grating structures on top of the optical waveguide 4. On the opposite edge, the waveguide 4 can either terminate next to or above the electron transparent window to allow the light to shine towards the sample.

[0044] Alternatively, in a second configuration as shown in figure 2, the waveguide 4 extends from a first edge of the substrate 2 to a second edge of the substrate 2 opposite to the first edge, wherein a core 4.1 of the waveguide 4 comprises the electron transparent window enabling the evanescent field to illuminate the sample. The light coming out of the second edge of the waveguide 4 can be collected by another optical fiber for further light sensing analysis, such as light spectrometry. The core 4.1 of waveguide 4 may comprise SiNx which is also the material used for the electron transparent window, hence the waveguide can be partially or completely part of the electron transparent window itself .

[0045] In all embodiments, a core 4.1 of the at least one optical waveguide 4 is embedded in a coating 4.2 having a lower index of refraction than the core 4.1.

[0046] Preferably the core 4.1 comprises silicon nitride and the coating 4.2 comprises silicon dioxide.

[0047] It is further preferable that the at least one optical waveguide 4 is at least partially devoid of coating 4.2 at or near to its first edge for optically coupling said at least one optical waveguide 4 with a light source by grating coupling or by direct coupling as already mentioned above.

[0048] The use of a seal chip 5 shown in figure 3 in combination with the waveguide 4 and the substrate 2 of the cartridge of the invention is illustrated in figures 4 and 5 for the 1stand the 2ndconfigurations of the cartridge 1 as shown in figures 1 and 2, respectively.

[0049] The seal chip 5 shown in figure 3 and applied in figures 4 and 5 on the substrate 2 comprises at least one channel but preferably two channels 7 that serve as inlet channel and outlet channel. A gasket 8 enables a leak tight inside chamber 6 and it may be installed in grooves or recessions on a lower side of the seal chip 5 for engaging with an upper side of the substrate 2. The seal chip 5 also comprises an electron transparent window 3.2 that is advantageously installed overlapping the window 3.1 of the substrate 2 to allow for an unhindered beam of electrons.

[0050] Advantageously, the optical waveguide 4 may be integrated on a surface of the seal chip 5, wherein the optical waveguide 4 extends from a first edge of said seal chip 5 towards the electron transparent window 3.2 of the seal chip 5, as illustrated in figure 6. More advantageously, the optical waveguide 4 may be integrated on a surface of the seal chip 5, wherein the optical waveguide 4 additionally extends from a second edge of said seal chip 5 towards the electron transparent window 3.2 of the seal chip 5 as illustrated in figure 7.

[0051] Although the invention has been discussed in the foregoing with reference to exemplary embodiments of the in-situ cartridge and holder of the invention, the invention is not restricted to these particular embodiment which can be varied in many ways without departing from the invention. The discussed exemplary embodiments shall therefore not be used to construe the append- ed claims strictly in accordance therewith. On the contrary the embodiments are merely intended to explain the wording of the appended claims without intent to limit the claims to these exemplary embodiments. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using these exemplary embodiments.

Claims

CLAIMS1. An in-situ cartridge (1) for electron microscopy and synchrotron applications comprising a substrate (2) for holding a sample, wherein said substrate (2) comprises an electron transparent window (3.1) and at least one optical waveguide (4) for illuminating said sample wherein a first edge of the at least one optical waveguide (4) is optically couplable with a light source, characterized in that the at least one optical waveguide (4) is integrated in and unitary with the substrate (2) and extends from an edge of the substrate (2) towards the electron transparent window (3.1) of the substrate (2) .

2. The in-situ cartridge (1) of claim 1, characterized in that the at least one optical waveguide (4) is provided in a layer intrinsically linked with or on the substrate (2) so as to arrange that the waveguide (4) and the substrate (2) are inseparable .

3. The in-situ cartridge (1) of claim 1 or 2, characterized in that the first edge of the at least one optical waveguide (4) is flush with the edge of the substrate (2) .

4. The in-situ cartridge (1) of any one of claims 1 - 3, characterized in that a core (4.1) of the at least one optical waveguide (4) is embedded in a coating (4.2) having a lower index of refraction than the core (4.1) .

5. The in-situ cartridge of claim 4, characterized in that the core (4.1) comprises silicon nitride and the coating (4.2) comprises silicon dioxide.

6. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the at least one opticalwaveguide (4) is at least partially devoid of coating (4.2) at or near to its first edge for optically coupling said at least one optical waveguide (4) with a light source by grating coupling or by direct coupling.

7. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the at least one optical waveguide (4) is provided on an upper side of the substrate (2) between the edge of the substrate (2) and the electron transparent window (3.1) of the substrate (2) .

8. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the core (4.1, fig. 2, 3, 6, 7) of the at least one optical waveguide (4) comprises the electron transparent window (3.1) of the substrate (2) , wherein said core (4.1) of the at least one optical waveguide (4) is at least partially uncoated to form the electron transparent window (3.1) of the substrate (2) .

9. The in-situ cartridge (1) of claim 8, characterized in that the uncoated part of the core (4.1) is thinner than the coated part of the core (4.1) .

10. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the in-situ cartridge (1) comprises a replaceable sealing chip (5) which is attachable to the substrate (2) for forming a chamber (6) in-between said sealing chip (5) and the substrate (2) , wherein the sealing chip (5) comprises:- an electron transparent window (3.2) ; at least one channel (7) for entering into or removing fluids from the chamber (6) ;- at least one cavity (9) around the electron transparent window (3.2) of the sealing chip (5) for receiving at least one gasket (8)- at least one gasket (8) in the at least one cavity, wherein said gasket (8) is engaged with the substrate (2) when the sealing chip (5) is attached to the substrate (2) .

11. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the electron transparent window (3.2) of the sealing chip (5) is overlapped with the electron transparent window (3.1) of the substrate (2) when the sealing chip (5) is attached to the substrate (2) .

12. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the substrate (2) comprises silicon.

13. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the substrate (2) comprises at least one metallic electrode.

14. The in-situ cartridge (1) of any one of the preceding claims 11-14, characterized in that the cartridge (1) comprises at least one spacer (13) between the substrate (2) and the sealing chip (5) for defining the chamber (6) between the substrate (2) and the seal chip (5) .

16. The in-situ cartridge (1) of any one of the preceding claims, characterized in that the optical waveguide (4) is integrated on a surface of the seal chip (5) and extends from a first edge of said seal chip (5) towards the electron transparent window (3.2) of the seal chip (5) .

17. The in-situ cartridge (1) of claim 16, characterized in that the optical waveguide (4) is integratedon a surface of the seal chip (5) and extends from a second edge of said seal chip (5) towards the electron transparent window (3.2) of the seal chip (5) .

18. A holder (14) for an in-situ cartridge (1) of any one of the preceding claims, characterized in that the holder (14) comprises an arm (10) , wherein said cartridge (1) is mountable to said arm (10) for holding the substrate (2) , and wherein said arm (10) comprises an optical fiber (11) for transmitting light from a first end of said arm (10) to a second end of said arm (10) where the substrate (2) is located.

19. The holder (14) of claim 18, characterized in that the optical fiber (11) is connectable to an external light source or to an external optical read-out device using an optical fiber connector (12) , such as Sub Miniature A.

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