Towards low-dimensional hole systems in Be-doped GaAs nanowires

Abstract

GaAs was central to the development of quantum devices but is rarely used for nanowire-based quantum devices with InAs, InSb and SiGe instead taking the leading role. p-type GaAs nanowires offer a path to studying strongly-confined 0D and 1D hole systems with strong spin-orbit effects, motivating our development of nanowire transistors featuring Be-doped p-type GaAs nanowires, AuBe alloy contacts and patterned local gate electrodes towards making nanowire-based quantum hole devices. We report on nanowire transistors with traditional substrate back-gates and EBL-defined metal/oxide top-gates produced using GaAs nanowires with three different Be-doping densities and various AuBe contact processing recipes. We show that contact annealing only brings small improvements for the moderately-doped devices under conditions of lower anneal temperature and short anneal time. We only obtain good transistor performance for moderate doping, with conduction freezing out at low temperature for lowly-doped nanowires and inability to reach a clear off-state under gating for the highly-doped nanowires. Our best devices give on-state conductivity 95 nS, off-state conductivity 2 pS, on-off ratio ~$10^4$, and sub-threshold slope 50 mV/dec at T = 4 K. Lastly, we made a device featuring a moderately-doped nanowire with annealed contacts and multiple top-gates. Top-gate sweeps show a plateau in the sub-threshold region that is reproducible in separate cool-downs and indicative of possible conductance quantization highlighting the potential for future quantum device studies in this material system.

References in corpus (19)

• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Spins in few-electron quantum dots
• Electron transport through double quantum dots
• Spin-orbit qubit in a semiconductor nanowire
• One-Dimensional Hole Gas in Germanium/Silicon Nanowire Heterostructures
• Double quantum dot with integrated charge sensor based on Ge/Si heterostructure nanowires
• What lurks below the last plateau: Experimental studies of the 0.7 x 2e^2/h conductance anomaly in one-dimensional systems
• Top-gate defined double quantum dots in InAs nanowires
• Realizing lateral wrap-gated nanowire FETs: Controlling gate length with chemistry rather than lithography
• Doping incorporation paths in catalyst-free Be-doped GaAs nanowires
• Spin-3/2 physics of semiconductor hole nanowires: Valence-band mixing and tunable interplay between bulk-material and orbital bound-state spin splittings
• High mobility two-dimensional hole system in GaAs/AlGaAs quantum wells grown on (100) GaAs substrates
• The Impact of Small-Angle Scattering on Ballistic Transport in Quantum Dots
• Observation of the Kondo Effect in a Spin-3/2 Hole Quantum Dot
• Observation of orientation- and $k$-dependent Zeeman spin-splitting in hole quantum wires on (100)-oriented AlGaAs/GaAs heterostructures
• Fabrication and characterization of an induced GaAs single hole transistor
• Using a tunable quantum wire to measure the large out-of-plane spin splitting of quasi two-dimensional holes in a GaAs nanostructure
• Interplay between one-dimensional confinement and crystallographic anisotropy in ballistic hole quantum wires
• Lande-like formula for the g factors of hole-nanowire subband edges

Cited by in corpus (3)

• Integrated bioelectronic proton-gated logic elements utilizing nanoscale patterned Nafion
• p-GaAs nanowire MESFETs with near-thermal limit gating
• Near-thermal limit gating in heavily-doped III-V semiconductor nanowires using polymer electrolytes