Electrical characterization of chemical and dielectric passivation of InAs nanowires
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abstract
The native oxide at the surface of III-V nanowires, such as InAs, can be a
major source of charge noise and scattering in nanowire-based electronics,
particularly for quantum devices operated at low temperatures. Surface
passivation provides a means to remove the native oxide and prevent its
regrowth. Here, we study the effects of surface passivation and conformal
dielectric deposition by measuring electrical conductance through nanowire
field effect transistors treated with a variety of surface preparations. By
extracting field effect mobility, subthreshold swing, threshold shift with
temperature, and the gate hysteresis for each device, we infer the relative
effects of the different treatments on the factors influencing transport. It is
found that a combination of chemical passivation followed by deposition of an
aluminum oxide dielectric shell yields the best results compared to the other
treatments, and comparable to untreated nanowires. Finally, it is shown that an
entrenched, top-gated device using an optimally treated nanowire can
successfully form a stable double quantum dot at low temperatures. The device
has excellent electrostatic tunability owing to the conformal dielectric layer
and the combination of local top gates and a global back gate.