Spin-Relaxation Dynamics ofE′Centers at High Density inSiO2Thin Films for Single-Spin Tunneling Force Microscopy

Abstract

The suitability of the spin-dynamics of paramagnetic silicon dangling bonds (E' centers) in high E'-density amorphous silicon dioxide (SiO2) as probe spins for single-spin tunneling force microscopy (SSTFM) is studied. SSTFM is a spin-selection rule based scanning-probe single-spin readout concept. Following the synthesis of SiO2 thin films on (111) oriented crystalline silicon substrates with room-temperature stable densities of [E ] > 5×10 18 cm −3 throughout the 60nm thin film, pulsed electron paramagnetic resonance spectroscopy was conducted on the E' centers at temperatures between T = 5K and T = 70K. The measurements revealed that the spin coherence (the transverse spin-relaxation time T2) of these centers is significantly shortened compared to low-E' density SiO2 films and within error margins not dependent on temperature. In contrast, the spin-flip times (the longitudinal relaxation times T1) are dependent on the temperature but with much weaker dependence than low-density SiO2, with greatest deviations from low-density SiO2 seen for T = 5K. These results, discussed in the context of the spin-relaxation dynamics of dangling bond states of other silicon-based disordered solids, indicate the suitability of E' centers in high-density SiO2 as probe spins for SSTFM.

An Efficient Method to Create High-Density Nitrogen-Vacancy Centers in Cvd Diamond for Sensing Applications

“…High energy and above bandgap photons generated from the Ar+ plasma were used to create dangling bonds in SiO2 [47][48][49]. The energy of Ar + in the plasma is very low, and the depth of the created NVcenter is more than 200 µm from the surface facing the plasma.…”