Gate length dependent transport properties of in-plane core-shell nanowires with raised contacts

Three-dimensional (3D) nanoscale crystal shaping has become essential for the precise design of advanced electronic and quantum devices based on electrically gated transport. In this context, III-V semiconductor-based nanowires with low electron effective mass and strong spin-orbit coupling are particularly investigated because of their exceptional quantum transport properties and the good electrostatic control they provide. Among the main challenges involved in the processing of these nanodevices are (i) the management of the gate stack which requires ex-situ passivation treatment to reduce the density of traps at the oxide/semiconductor interface, (ii) the ability to get good ohmic contacts for source and drain electrodes and (iii) the scalability and reliability of the process for the fabrication of complex architectures based on nanowire networks. In this paper, we show that selective area molecular beam epitaxy of in-plane InGaAs/InP core-shell nanowires with raised heavily doped source and drain contacts can address these different issues. Electrical characterization of the devices down to 4 K reveals the positive impact of the InP shell on the gate electrostatic control and effective electron mobility. Although comparable to the best reported values for In(Ga)As nanostructures grown on InP, this latter is severely reduced for sub-100 nm channel highlighting remaining issue to reach the ballistic regime.