An electron source (2) for generating an electron beam (8) having a cathode (1) and an anode (4) in the form of a graphene layer (6, 12) epitaxially grown on a silicon carbide substrate (5). The invention is suitable for monolithic preparation of a miniaturized source of a high-energy focused electron beam, including its use as an on-chip X-ray source. All components can be prepared from or on a single silicon carbide chip.

In an embodiment, a method includes forming a first diamond layer on a substrate and inducing a layer of graphene from the first diamond layer by heating the substrate and the first diamond layer. The method includes forming a second diamond layer on top of the layer of graphene and applying a mask to the second diamond layer. The mask includes a shape of a cathode, an anode, and one or more grids. The method further includes forming a two-dimensional cold cathode, a two-dimensional anode, and one or more two-dimensional grids by reactive-ion electron-beam etching. Each of the two-dimensional cold cathode, the two-dimensional anode, and the one or more two-dimensional grids includes a portion of the first diamond layer, the graphene layer, and the second diamond layer such that the graphene layer is positioned between the first diamond layer and the second diamond layer.

An electron emission device includes a substrate and an electron emission layer. The electron emission layer is provided above the substrate, and is provided with an opening. The electron emission layer has an edge defining the opening and is configured to emit electrons from the edge when the edge is irradiated with light.

A horizontal multilayer junction-edge field emitter includes a plurality of vertically-stacked multilayer structures separated by isolation layers. Each multilayer structure is configured to produce a 2-dimensional electron gas at a junction between two layers within the structure. The emitter also includes an exposed surface intersecting the 2-dimensional electron gas of each of the plurality of vertically-stacked multilayer structures to form a plurality of effectively one-dimensional horizontal line sources of electron emission.

In an embodiment, a method includes forming a first diamond layer on a substrate and inducing a layer of graphene from the first diamond layer by heating the substrate and the first diamond layer. The method includes forming a second diamond layer on top of the layer of graphene and applying a mask to the second diamond layer. The mask includes a shape of a cathode, an anode, and one or more grids. The method further includes forming a two-dimensional cold cathode, a two-dimensional anode, and one or more two-dimensional grids by reactive-ion electron-beam etching. Each of the two-dimensional cold cathode, the two-dimensional anode, and the one or more two-dimensional grids includes a portion of the first diamond layer, the graphene layer, and the second diamond layer such that the graphene layer is positioned between the first diamond layer and the second diamond layer.

In an embodiment, a method includes forming a first diamond layer on a substrate and inducing a layer of graphene from the first diamond layer by heating the substrate and the first diamond layer. The method includes forming a second diamond layer on top of the layer of graphene and applying a mask to the second diamond layer. The mask includes a shape of a cathode, an anode, and one or more grids. The method further includes forming a two-dimensional cold cathode, a two-dimensional anode, and one or more two-dimensional grids by reactive-ion electron-beam etching. Each of the two-dimensional cold cathode, the two-dimensional anode, and the one or more two-dimensional grids includes a portion of the first diamond layer, the graphene layer, and the second diamond layer such that the graphene layer is positioned between the first diamond layer and the second diamond layer.

A horizontal multilayer junction-edge field emitter includes a plurality of vertically-stacked multilayer structures separated by isolation layers. Each multilayer structure is configured to produce a 2-dimensional electron gas at a junction between two layers within the structure. The emitter also includes an exposed surface intersecting the 2-dimensional electron gas of each of the plurality of vertically-stacked multilayer structures to form a plurality of effectively one-dimensional horizontal line sources of electron emission.

In an embodiment, a method includes forming a first diamond layer on a substrate and inducing a layer of graphene from the first diamond layer by heating the substrate and the first diamond layer. The method includes forming a second diamond layer on top of the layer of graphene and applying a mask to the second diamond layer. The mask includes a shape of a cathode, an anode, and one or more grids. The method further includes forming a two-dimensional cold cathode, a two-dimensional anode, and one or more two-dimensional grids by reactive-ion electron-beam etching. Each of the two-dimensional cold cathode, the two-dimensional anode, and the one or more two-dimensional grids includes a portion of the first diamond layer, the graphene layer, and the second diamond layer such that the graphene layer is positioned between the first diamond layer and the second diamond layer.

A horizontal multilayer junction-edge field emitter includes a plurality of vertically-stacked multilayer structures separated by isolation layers. Each multilayer structure is configured to produce a 2-dimensional electron gas at a junction between two layers within the structure. The emitter also includes an exposed surface intersecting the 2-dimensional electron gas of each of the plurality of vertically-stacked multilayer structures to form a plurality of effectively one-dimensional horizontal line sources of electron emission.

An electron emission device includes a substrate and an electron emission layer. The electron emission layer is provided above the substrate, and is provided with an opening. The electron emission layer has an edge defining the opening and is configured to emit electrons from the edge when the edge is irradiated with light.