Automated tuning and characterization of single-electron and single-hole transistor charge sensors

Abstract

We present an automated protocol for tuning single-electron transistors (SETs) and single-hole transistors (SHTs) to operate as high-sensitivity DC charge sensors. The protocol initializes a previously unmeasured device after cooldown, identifies a working point in barrier-gate space, and selects and ranks charge-sensing operating points. It further automates the acquisition and analysis of Coulomb diamonds to extract sensor-relevant parameters, including lever arm, charging energy, gate and source/drain capacitances, and estimated dot radius. We demonstrate the protocol on accumulation-mode silicon MOS SET and SHT devices operated at 1.5 K and $\approx 50$ mK, respectively, establishing ambipolar applicability across a wide temperature range. Operation at 1.5 K indicates that charge sensing in compact MOS devices is feasible in the 1-2 K regime, supporting higher-temperature readout relevant to scalable spin-qubit architectures. Compared to manual tuning, automation reduces operator overhead and provides consistent device characterization, with clear pathways for further speedups and improved robustness via faster electronics and feedback-based stabilization.