Epitaxial Growth of Planar Hutwires on Silicon‐on‐Insulator Substrates

Quantum devices based on holes confined in crystalline Ge nanostructures have emerged as a promising platform in the field of quantum technology. Epitaxial Ge hutwires (HWs) successfully used in pioneering quantum bit (qubit) experiments are the logical next choice for long‐distance coherent spin–spin coupling experiments. However, leakage currents are currently limiting the device performance of HWs on bulk Si substrates. This drawback can be mitigated by the HW growth on silicon‐on‐insulator (SOI) substrates. Herein, molecular beam epitaxy (MBE) HW growth developed on technologically relevant SOI substrates with different device layer thicknesses is shown. Using atomic force microscopy characterization, the fabrication of HWs on SOI with lengths of up to 600 nm is demonstrated. In addition, the very narrow window of growth parameters for which successful HW growth can be achieved and the distinct differences of HW growth on SOI versus bulk Si substrates are addressed.