Study of gold thin films evaporated on polyethylene naphthalate films toward the fabrication of quantum cross devices

We have studied Au thin films evaporated on polyethylene naphtalate (PEN) organic substrates as a function of Au thickness < ̃20 nm and discussed its feasibility toward metal/insulator hybrid materials used for quantum cross devices using atomic force microscope. The Au grain size increases from 28.0 ±4.6 nm to 48.5 ±11.4 nm with increasing the Au thickness from 6.9 to 20.8 nm and it denotes that the Au grain size is larger than its Au-thickness size, respectively. The surface roughness of Au films of sub-15-nm thickness, in the scanning scale of the Au-thickness size, is less than 0.9 nm, corresponding to 4-5 atomic layers. These experimental results indicate that Au thin films on PEN substrates are suitable for possible metal/insulator hybrid materials to be used in quantum cross devices.