Abstract
Laterally grown InxGa1−xAs nanowires (NWs) are promising candidates for radio frequency and quantum computing applications, which, however, can require atomic scale surface and interface control. This is challenging to obtain, not least due to ambient air exposure between fabrication steps, which induces surface oxidation. The geometric and electronic surface structures of InxGa1−xAs NWs and contacts, which were grown directly in a planar configuration, exposed to air, and then subsequently cleaned using atomic hydrogen, are studied using low-temperature scanning tunneling microscopy and spectroscopy (STM/S). Atomically flat facets with a root mean square roughness of 0.12 nm and the InGaAs (001) 4 × 2 surface reconstruction are observed on the top facet of the NWs and the contacts. STS shows a surface bandgap variation of 30 meV from the middle to the end of the NWs, which is attributed to a compositional variation of the In/Ga element concentration. The well-defined facets and small bandgap variations found after area selective growth and atomic hydrogen cleaning are a good starting point for achieving high-quality interfaces during further processing.
Highlights
Selectively grown lateral NWs have gained significant interest
We focus on metalÀorganic vapor phase epitaxy (MOVPE) laterally grown InxGa1ÀxAs NWs, relevant for both radio frequency and quantum computing applications.[2,9]
After the MOVPE growth of the NWs, the sample will be exposed to air as it is moved to other deposition systems, for example, to apply superconducting contacts and perform lithography involved in device fabrication
Summary
Selectively grown lateral NWs have gained significant interest. This so-called template-assisted selective epitaxy (TASE)[7,8] or selective area growth (SAG)[9,10,11] is especially promising for applications such as metal–oxide–semiconductor field-effect transistors (MOSFET) for radio frequency applications[9,12,13] and for quantum transport in lateral NWs for Majorana-based semiconductor/superconductor qubits.[1,2,3,4,5]. The geometric and electronic surface structures of InxGa1ÀxAs NWs and contacts, which were grown directly in a planar configuration, exposed to air, and subsequently cleaned using atomic hydrogen, are studied using lowtemperature scanning tunneling microscopy and spectroscopy (STM/S).
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