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 Pb state, which dominates at low magnetic fields. While magnetic resonant current responses due to 31P and Pb states are still present, they do not correlate and only the Pb contribution can be associated with an interface process due to spin-dependent tunneling between energetically and physically adjacent Pb 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.