Spin-dependent processes at the crystalline Si-SiO₂ interface at high magnetic fields

An experimental study on the nature of spin-dependent excess charge-carrier transitions at the interface between (111)-oriented phosphorous-doped ([P]≈10¹⁵ cm⁻³) crystalline silicon and silicon dioxide at high magnetic field (B₀≈8.5 T) is presented. Electrically detected magnetic-resonance (EDMR) spectra of the hyperfine split ³¹P donor-electron transitions and paramagnetic interface defects were conducted at temperatures in the range of 3 K≤T≤12 K. The results at these previously unattained (for EDMR) magnetic-field strengths reveal the dominance of spin-dependent processes that differ from the previously well investigated recombination between the ³¹P donor and the P_b state, which dominates at low magnetic fields. While magnetic resonant current responses due to ³¹P and P_b states are still present, they do not correlate and only the P_b contribution can be associated with an interface process due to spin-dependent tunneling between energetically and physically adjacent P_b states. This work provides an experimental demonstration of spin-dependent tunneling between physically adjacent and identical electronic states as proposed by Kane Nature (London) 393 133 (1998)] for readout of donor qubits.