Abstract: A semiconductor device is provided comprising a bilayer graphene comprising a first and a second adjacent graphene layer, and a first electrically insulating layer contacting the first graphene layer, the first electrically insulating layer comprising an electrically insulating material, and a substance suitable for creating free charge carriers of a first type in the first graphene layer, the semiconductor device further comprising an electrically insulating region contacting the second graphene layer and suitable for creating free charge carriers of a second type, opposite to the first type, in the second graphene layer.

Abstract: A method for producing a colloid of metallic nanoparticles including the steps of: providing metal ions in solution; providing a stabilizing agent; and reducing said metal ions in the presence of said stabilizing agent, so that metallic nanoparticles are formed with a surrounding layer of said stabilizing agent, wherein the reduction step is carried out at a temperature of not less than 20° C. and not more than 150° C. The metallic nanoparticles are formed of a mixture of transition metal and noble metal, such as Ni—Pd. The resultant nanoparticles have a high stability in terms of size and chemical degradation and so can be stored for long periods. They are therefore particularly suited for forming patterned nanoparticle arrays on a substrate by nanocontact printing for the subsequent formation of a corresponding array of carbon nanotubes or nanofibers via plasma enhanced CVD.