Electron device and method for manufacturing an electron device

1. An electron device comprising:

a support substrate;

a conductive planar slow-wave structure on the support substrate, the conductive planar slow-wave structure being adapted to receive an electromagnetic wave signal for interaction with an electron beam; and

a dielectric layer arrangement in between the conductive planar slow-wave structure and the support substrate, the dielectric layer arrangement being arranged on the support substrate only on one or more portions of the support substrate which are overlapped by the conductive planar slow-wave structure.

2. The electron device as claimed in claim 1 , wherein the dielectric layer arrangement contacts the conductive planar slow-wave structure.

3. The electron device as claimed in claim 2 , wherein the dielectric layer arrangement contacts only a surface of the conductive planar slow-wave structure facing the support substrate.

4. The electron device as claimed in claim 1 , wherein the support substrate comprises dopants.

5. The electron device as claimed in claim 1 , wherein the conductive planar slow wave structure comprises a planar helix structure, the planar helix structure comprising:

a plurality of first elements on a first portion of the support substrate;

a plurality of second elements on a second portion of the support substrate, wherein the plurality of first elements and the plurality of second elements are arranged one over the other; and

a plurality of connectors, each respective connector of the plurality of connectors is arranged to connect an end region of an associated first element of the plurality of first elements to an end region of an associated second element of the plurality of second elements, and

wherein the dielectric layer arrangement comprises:

a first dielectric layer in between the plurality of first elements and the first portion of the support substrate, the first dielectric layer being arranged on the first portion of the support substrate at only one or more support substrate portions overlapping with the plurality of first elements, and

a second dielectric layer in between the plurality of second elements and the second portion of the support substrate, the second dielectric layer being arranged on the second portion of the support substrate at only one or more support substrate portions overlapping with the plurality of second elements.

6. The electron device as claimed in claim 5 , wherein the plurality of first elements and the plurality of second elements are inclined at symmetric angles of opposite signs.

7. The electron device as claimed in claim 5 , wherein the plurality of connectors are vertical connectors.

8. The electron device as claimed in claim 5 , wherein each of the end region of the associated first element and the end region of the associated second element comprises a circular pad connected to the respective connector.

9. The electron device as claimed in claim 8 , wherein a cross-sectional dimension of the circular pad is larger than a cross-sectional dimension of the respective connector.

10. The electron device as claimed in claim 1 , wherein the conductive planar slow wave structure comprises a meander line structure.

11. The electron device as claimed in claim 10 , wherein the meander line structure comprises:

a first meander line element on a first portion of the support substrate; and

a second meander line element on a second portion of the support substrate, wherein the first meander line element and the second meander line element are arranged one over the other and spaced apart from each other, and

wherein the dielectric layer arrangement comprises:

a first dielectric layer in between the first meander line element and the first portion of the support substrate, the first dielectric layer being arranged on the first portion of the support substrate at only one or more support substrate portions overlapping with the first meander line element, and

a second dielectric layer in between the second meander line element and the second portion of the support substrate, the second dielectric layer being arranged on the second portion of the support substrate at only one or more support substrate portions overlapping with the second meander line element.

12. The electron device as claimed in claim 1 , wherein the conductive planar slow wave structure comprises an interdigitated structure, the interdigitated structure comprising:

a plurality of first interdigital elements on a first portion of the support substrate, the plurality of first interdigital elements being coupled to each other; and

a plurality of second interdigital elements on a second portion of the support substrate, the plurality of second interdigital elements being coupled to each other, wherein the plurality of first interdigital elements and the plurality of second interdigital elements are arranged one over the other and interdigitated with each other, and

wherein the dielectric layer arrangement comprises:

a first dielectric layer in between the plurality of first interdigital elements and the first portion of the support substrate, the first dielectric layer being arranged on the first portion of the support substrate at only one or more support substrate portions overlapping with the plurality of first interdigital elements, and

a second dielectric layer in between the plurality of second interdigital elements and the second portion of the support substrate, the second dielectric layer being arranged on the second portion of the support substrate at only one or more support substrate portions overlapping with the plurality of second interdigital elements.

13. The electron device as claimed in claim 1 , wherein a dielectric constant of the dielectric layer arrangement is lower than a dielectric constant of the support substrate.

14. The electron device as claimed in claim 1 , wherein an electrical conductivity of the dielectric layer arrangement is lower than an electrical conductivity of the support substrate.

15. The electron device as claimed in claim 1 , further comprising a metallic enclosure arranged to surround the conductive planar slow-wave structure.

16. The electron device as claimed in claim 1 , further comprising an electron source configured to generate the electron beam.

17. The electron device as claimed in claim 1 , wherein the electron device is a travelling-wave tube.

18. A method for manufacturing an electron device, the method comprising:

providing a support substrate;

forming a conductive planar slow-wave structure on the support substrate, the conductive planar slow-wave structure being adapted to receive an electromagnetic wave signal for interaction with an electron beam; and

forming a dielectric layer arrangement in between the conductive planar slow-wave structure and the support substrate, the dielectric layer arrangement being arranged on the support substrate only on one or more portions of the support substrate which are overlapped by the conductive planar slow-wave structure.

19. The method as claimed in claim 18 , further comprising doping the support substrate with dopants.

20. The method as claimed in claim 18 ,

wherein the planar slow wave structure comprises a planar helix structure, and

wherein forming the planar slow wave structure comprises:

forming a plurality of first elements on a first portion of the support substrate;

forming a plurality of second elements on a second portion of the support substrate, wherein the plurality of first elements and the plurality of second elements are arranged one over the other; and

forming a plurality of connectors, each respective connector of the plurality of connectors is arranged to connect an end region of an associated first element of the plurality of first elements to an end region of an associated second element of the plurality of second elements, and

wherein forming a dielectric layer arrangement comprises:

forming a first dielectric layer in between the plurality of first elements and the first portion of the support substrate, the first dielectric layer being arranged on the first portion of the support substrate at only one or more support substrate portions overlapping with the plurality of first elements; and

forming a second dielectric layer in between the plurality of second elements and the second portion of the support substrate, the second dielectric layer being arranged on the second portion of the support substrate at only one or more support substrate portions overlapping with the plurality of second elements.