  Quantum dots patterned by atomically precise placement of phosphorus donors
in single crystal silicon have long spin lifetimes, advantages in
addressability, large exchange tunability, and are readily available
few-electron systems. To be utilized as quantum bits, it is important to
non-invasively characterise these donor quantum dots post fabrication and
extract the number of bound electron and nuclear spins as well as their
locations. Here, we propose a metrology technique based on electron spin
resonance (ESR) measurements with the on-chip circuitry already needed for
qubit manipulation to obtain atomic scale information about donor quantum dots
and their spin configurations. Using atomistic tight-binding technique and
Hartree self-consistent field approximation, we show that the ESR transition
frequencies are directly related to the number of donors, electrons, and their
locations through the electron-nuclear hyperfine interaction.
