Integrable Germanium Few-Hole Double Quantum-Dots and Single-Hole Transistors using CMOS Fabrication Apporaches

We report Ge few-hole double quantum-dots (DQDs) integrable with single-hole transistors (SHTs) for high-sensitivity charge detection. Ge DQDs with 20 nm diameter are closely coupled via a 10 nm-thick Si barrier, inducing strong inter-QD coupling. Thanks to strong quantum confinement induced by self-organized, hard-wall barriers of
$\mathbf{Si}_{3}\mathbf{N}_{4}/\mathbf{SiO}_{2}$
, Ge SHT exhibits aperiodic oscillatory current behaviors with high peak to valley current ratio
$(> 200)$
, low leakage
$(\sim 40\ \mathbf{fA})$
, and large addition energy
$(> 15\ \mathbf{meV})$
, offering great promises for high-fidelity charge sensing.