Transport Measurements of Surface Electrons in 200-nm-Deep Helium-Filled Microchannels Above Amorphous Metallic Electrodes
We report transport measurements of electrons on helium in a microchannel device where the channels are 200 nm deep and 3μm wide. The channels are fabricated above amorphous metallic Ta 40 W 40 Si 20 , which has surface roughness below 1 nm and minimal variations in work function across the surface due to the absence of polycrystalline grains. We are able to set the electron density in the channels using a ground plane. We estimate a mobility of 300cm 2 /Vs and electron densities as high as 2.56×10 9 cm -2 . We demonstrate control of the transport using a barrier which enables pinch-off at a central microchannel connecting two reservoirs. The conductance through the central microchannel is measured to be 10 nS for an electron density of 1.58×10 9 cm -2 . Lastly, our work extends transport measurements of surface electrons to thin helium films in microchannel devices above metallic substrates.