An apparatus and method of forming an apparatus comprising a graphene field effect transistor

An apparatus comprising:

• a graphene field effect transistor where the graphene field effect transistor comprises a graphene channel and quantum dots provided overlaying the graphene channel, wherein
• the quantum dots comprise a first layer comprising quantum dots connected to a first ligand and a second layer comprising quantum dots connected to a second ligand, wherein
• the first ligand is configured to cause the first layer to have a first refractive index and the second ligand is configured to cause the second layer to have a second refractive index wherein the second refractive index is different to the first refractive index, wherein
• the thickness of at least one of the layers of quantum dots is arranged to provide an anti-reflective coating, and wherein
• the layers arranged to provide an anti-reflective coating are also arranged to transduce incident light into an electrical output.

A photodetector comprising at least one apparatus, the at least one apparatus comprising:

• a graphene field effect transistor where the graphene field effect transistor comprises a graphene channel and quantum dots provided overlaying the graphene channel, wherein
• the quantum dots comprise a first layer comprising quantum dots connected to a first ligand and a second layer comprising quantum dots connected to a second ligand, wherein
• the first ligand is configured to cause the first layer to have a first refractive index and the second ligand is configured to cause the second layer to have a second refractive index wherein the second refractive index is different to the first refractive index, wherein
• the thickness of at least one of the layers of quantum dots is arranged to provide an anti-reflective coating, and wherein the layers arranged to provide an anti-reflective coating are also arranged to transduce incident light into an electrical output.

A method comprising:

• depositing a first layer of quantum dot solution onto a graphene channel of a graphene field effect transistor;
• exchanging ligands to form a first layer of quantum dots connected to a first ligand;
• depositing a second layer of quantum dot solution overlaying the first layer of quantum dots;
• and
• exchanging ligands to form a second layer of quantum dots connected to a second ligand;
• wherein the first ligand is configured to cause the first layer to have a first refractive index and the second ligand is configured to cause the second layer to have a second refractive index wherein the second refractive index is different to the first refractive index, wherein
• the thickness of at least one of the layers of quantum dots is arranged to provide an anti-reflective coating, and wherein
• the layers arranged to provide an anti-reflective coating are also arranged to transduce incident light into an electrical output.