Field effect enhancement in buffered quantum nanowire networks

Abstract

III-V semiconductor nanowires have shown great potential in various quantum transport experiments. However, realizing a scalable high-quality nanowire-based platform that could lead to quantum information applications has been challenging. Here, we study the potential of selective area growth by molecular beam epitaxy of InAs nanowire networks grown on GaAs-based buffer layers. The buffered geometry allows for substantial elastic strain relaxation and a strong enhancement of field effect mobility. We show that the networks possess strong spin-orbit interaction and long phase coherence lengths with a temperature dependence indicating ballistic transport. With these findings, and the compatibility of the growth method with hybrid epitaxy, we conclude that the material platform fulfills the requirements for a wide range of quantum experiments and applications.Material science plays a key role in quantum computing research. Long quantum state lifetimes -the fundamental prerequisite for realizing quantum computers -rely on the ability to produce materials with high purity and structural quality. Together with the requirements of scalability and reproducibility, these properties are what mainly defines the challenges of material science in quantum computing today. Proposals for topological quantum computing, 1-3 which are based on hybrid semiconductor-superconductor nanowire (NW) networks, are being pursued by numerous research groups and have ignited intense research efforts on hybrid epitaxy. 4-8 NW scalability is tightly related to the semiconductor growth approach. Top-down lithography has been used to define NWs in two-dimensional layers 5,9 and a variety of methods have been pursued for alignment and positioning of bottom-up vapor-liquid-solid (VLS) grown NWs, such as dielectrophoresis techniques, 10 nanoscale combing 11 and magnetic aligning of NWs. 12 Despite of these developments, large-scale synthesis of bottom-up grown high-mobility NW networks that are compatible with epitaxial interwire connections and semiconductor/superconductor epitaxy has still not been realized. To realize the epitaxial connections, a lot of effort has been put into the growth of branched NWs via the VLS method. 8,13-15 A scalable approach has been developed in Ref. [16,17] using template assisted growth of inplane NW networks. 18 Nonetheless, this approach is not yet compatible with superconductor epitaxy. An alternative scalable approach is to use lithographically defined openings in a mask on a crystalline substrate. This method is referred to as selective area growth (SAG) and until recently has mainly been used in conjunction with metal organic chemical vapour deposition 19,20 , metal organic vapour phase epitaxy 21,22 , chemical beam epitaxy and metal organic molecular beam epitaxy (chemical beam epitaxy). [23][24][25][26] In contrast to molecular beam epitaxy (MBE), the dissociation kinetics of the chemical precursors in these methods enhance the growth selectivity on masked substrates by expanding the growth parameter window, ...

Site‐Controlled Uniform Ge/Si Hut Wires with Electrically Tunable Spin–Orbit Coupling

“…[ 29 ] The out‐of‐plane grown NW structures, however, need to be transferred from the growth wafer to a second substrate for device fabrication, which limits their scalability. [ 7,29 ] Very recently, high‐quality in‐plane NW networks have been successfully demonstrated with selective‐area [ 30,31 ] and template‐assisted [ 32 ] growth techniques, but the problems related to growth imperfections such as dislocation and polytypism still remain. In addition, the selective‐area growth works only for material systems that have good growth selectivity between oxides and semiconductors.…”

Robust and Clean Majorana Zero Mode in the Vortex Core of High-Temperature Superconductor (Li0.84Fe0.16)OHFeSeLiu1, Chen2, Zhang3 et al. 2018Phys. Rev. X20511251View full textAdd to dashboardCite

“…A quantized ZBCP has been observed in the tunneling spectrum of a hybrid device between superconducting aluminum and an InSb nanowire [9], providing compelling evidence for a MZM. However, fundamental quantum computing operations such as braiding of MZMs in nanowires [10] are challenging and yet to be realized after a tremendous amount of ingenious technical endeavor [11,12].…”

Supercurrent carried by nonequilibrium quasiparticles in a multiterminal Josephson junction

“…Recent progress in fabrication of hybrid nanodevices driven by the pursuit for creation topological quantum gates [20][21][22] led to creation of tunable multiterminal systems based on crossed nanowires [23][24][25][26] or gated graphene [27]. Termination of such structures by super-conducting leads allows to form multiterminal Josephson junctions that serve as superconducting beam splitters that entangle Cooper pairs [28 and 29], allow to obtain Shapiro steps [30] due to voltage-induced supercurrent and where the transconductance due to AC Josephson effect is quantized in units of 4e 2 /h [31 and 32].…”