Electrical spin measurements of diffused phosphorous donors in crystalline silicon

With recent experimental demonstration of the electrical detection of electron spins of phosphorous donors as well as their hyperfine coupling to the $^{31}$P phosphorous nuclear spin [Stegner et al., Nature Physics, doi:10.1038/nphys465, (2006).], a potential mechanism for a $^{31}$P in crystalline silicon (c-Si) nuclear spin readout based on spin-dependent $^{31}$P -$\mathrm{P_b}$ recombination is available. To further investigate the properties of this mechanism, we present pulsed electrically detected magnetic resonance (pEDMR) measurements on diffusion doped silicon samples. For their preparation, c-Si (111) wafers are diffused with a profile whose concentration at the surface leads to a degenerately doped c-Si before it then drops off into the semiconducting region. Deep trenches are made with a plasma enhanced reactive ion etch where the choice of the trench depth determines the dopant concentration of the sample without changing any other sample preparation parameters. A study of the qualitative and quantitative nature of the observed pEDMR signals is presented for different etch depths.