Hall Measurement on Regrown Nanowires

University essay from Lunds universitet/Fysiska institutionen

Abstract: Ternary semiconductor alloys like $In_xGa_{1-x}As$ have lured competing attention in connection to sub-50 nm high performance, low power, planar Complementary Metal Oxide Semiconductor technology. This compound semiconductor owes its popularity to excellent bulk carrier mobility, minority carrier diffusion constant, small bandgap, high electron injection velocity and its capability to take Moore's law beyond silicon platform. Though they exhibit exceptional properties in their bulk, their properties in confined architectures like a nanowire (NW) still remains relatively less explored. In this work, the transport properties of $In_xGa_{1-x}As$ is explored in a planar confined device architecture, by performing \textbf{Hall Measurements} on $In_xGa_{1-x}As$ NWs, in a home built measurement setup. The device of interest is fabricated with the help of Electron Beam Lithography (EBL) and a novel method of \textbf{selective area regrowth}. The pattern is made with the help of Hydrogen Silesquixone (HSQ) negative tone E-beam resist on a semi-insulating InP substrate. The device geometry allows placement of probe electrodes exactly opposite to each other, which is very important to extract Hall voltage and hence the mobility of the NW. Ti/Pd and Au bilayer is used to make the contact pads which are again defined by EBL with PMMA positive E-beam resist. The samples were mounted on an insulating ceramic holder and each device was manually wire bonded to the contact pins using a 0.25 \textmu m gauge aluminium wire. And Hall measurements were performed on the successful devices at room temperature. For the proposed geometry, the devices exhibited electron mobility values $ \approx (5000 \pm 800)$ cm$^2$/Vs.

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