Developing Single Layer MOS Quantum Dots for Diagnostic Qubits.

The design, fabrication and characterization of single metal gate layer, metal-oxide-semiconductor (MOS) quantum dot devices robust against dielectric breakdown are presented as prototypes for future diagnostic qubits. These devices were developed as a preliminary solution to a longer term goal of a qubit platform for intercomparison between materials or for in-line diagnostics, and to provide a testbed for establishing classical measurements predictive of coherence performance. For this stage, we seek a robust MOS design that is compatible with wafer and chip architectures, that has a reduced process overhead and is sufficiently capable of challenging and advancing our measurement capabilities. In this report, we present our initial batch of silicon MOS devices using a single gate layer, which have not exhibited any failures with gate voltage excursions > 10 V, but do exhibit the reduced electrostatic control expected of a single gate layer design. We observe quantum dot formation, capacitive charge sensing between channels, and reasonable effective electron temperatures that enable spin qubit studies. The costs and benefits of the trade-off between device performance and fabrication efficiency will be discussed, as well as opportunities for future improvements.