Bias spectroscopy and simultaneous SET charge state detection of Si:P double dots

TL;DR

This study investigates silicon double-dot systems with phosphorous doping at millikelvin temperatures, utilizing bias spectroscopy and single-electron transistor sensing to analyze charge states and Coulomb interactions.

Contribution

It demonstrates simultaneous charge state detection via SET sensing and current measurements, providing detailed insights into double-dot charge dynamics and Coulomb effects.

Findings

Successful simultaneous detection of charge states and current.

Observation of Coulomb diamonds and triple point evolution.

Comparison of experimental data with numerical simulations.

Abstract

We report a detailed study of low-temperature (mK) transport properties of a silicon double-dot system fabricated by phosphorous ion implantation. The device under study consists of two phosphorous nanoscale islands doped to above the metal-insulator transition, separated from each other and the source and drain reservoirs by nominally undoped (intrinsic) silicon tunnel barriers. Metallic control gates, together with an Al-AlOx single-electron transistor, were positioned on the substrate surface, capacitively coupled to the buried dots. The individual double-dot charge states were probed using source-drain bias spectroscopy combined with non-invasive SET charge sensing. The system was measured in linear (VSD = 0) and non-linear (VSD <> 0) regimes allowing calculations of the relevant capacitances. Simultaneous detection using both SET sensing and source-drain current measurements was demonstrated, providing a valuable combination for the analysis of the system. Evolution of the triple points with applied bias was observed using both charge and current sensing. Coulomb diamonds, showing the interplay between the Coulomb charging effects of the two dots, were measured using simultaneous detection and compared with numerical simulations.