Magnetic resonance force detection and spectroscopy of electron spins in phosphorus-doped silicon

Electron spin resonance (ESR) of phosphorus-doped silicon was detected using a low temperature magnetic resonance force microscope (MRFM). Force-detected ESR spectra were obtained using an amplitude or frequency modulated microwave field to cyclically saturate the spin magnetization. For a sample containing 4×10 18 phosphorus atoms/ cm 3 , a single strong ESR line was observed. For a sample containing 8×10 16 phosphorus atoms/ cm 3 , a pair of lines split by the 42 G 31 P hyperfine interaction was observed. This result demonstrates the possibility of using MRFM techniques for spectroscopic purposes.