Quantum 2025 – scientific programme

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MON: Monday Contributed Sessions

MON 21: Quantum Materials

MON 21.7: Talk

Monday, September 8, 2025, 18:00–18:15, ZHG103

Shadow Wall Epitaxy - Towards the all-in-situ fabrication of ZnSe-based Quantum Devices — •Christine Falter^{1, 2}, Yurii Kutovyi^{1, 2}, Nils von den Driesch^{1, 2}, Denny Dütz^{2, 3}, Lars R. Schreiber^{2, 3}, and Alexander Pawlis^{1, 2} — ¹Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany — ²JARA-FIT, Jülich Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, Germany — ³JARA-Institute for Quantum Information, RWTH Aachen University, 52074 Aachen, Germany

Wide band-gap semiconductors such as ZnSe offer a wide range of unique properties making them well-suited for a variety of quantum devices. However, in standard fabrication schemes, surface states and defects introduced during ex-situ applied processing steps can limit the performance of the final device. With this in mind, we have developed a Shadow Wall technique for molecular beam epitaxy (MBE), which allows for all-in-situ device fabrication making all post processing steps obsolete. The technique relies on the pre-patterning of vertical walls on the substrate and the precise alignment of material fluxes during deposition. In our contribution, we focus on the realization of an all-in-situ ZnSe-based field effect transistor (FET). We demonstrate the MBE growth of high quality ZnSe layers on pre-patterned substrates, the in-situ realization of well-defined spatially separated metal contacts and the electrical characterization of the final device. The optimization of the ZnSe FET platform is a first step towards the realization of qubits based on gate defined quantum dots in ZnSe.

Keywords: Molecular Beam Epitaxy; Compound Semiconductors; Shadow Wall Epitaxy; Field Effect Transistor; Spin Qubits