High-resolution photothermal ionization spectroscopy of lithium-related shallow donors in germanium

Abstract

High-resolution (0.10 ${\mathrm{cm}}^{\ensuremath{-}1}$ full width at half maximum) photothermal ionization spectroscopy has resolved the ground-state splitting of interstitial lithium into a singlet (${E}_{1S({A}_{1})}\ensuremath{-}{E}_{2P\ifmmode\pm\else\textpm\fi{}}=66.61$ ${\mathrm{cm}}^{\ensuremath{-}1}$) and a triplet (${E}_{1S({T}_{2})}\ensuremath{-}{E}_{2P\ifmmode\pm\else\textpm\fi{}}=66.98$ ${\mathrm{cm}}^{\ensuremath{-}1}$), and resolved four different $1S$ states of the $D(\mathrm{L}\mathrm{i},\mathrm{O})$ complex: ${E}_{1S}\ensuremath{-}{E}_{2P\ifmmode\pm\else\textpm\fi{}}=61.75, 66.54, 67.05, \mathrm{and} 70.50$ ${\mathrm{cm}}^{\ensuremath{-}1}$. In siliconrich samples with [Li] > [O], a new complex, $D(\mathrm{Li},X)$, was observed with ${E}_{1S}\ensuremath{-}{E}_{2P\ifmmode\pm\else\textpm\fi{}}=70.72 \mathrm{and} 67.24$ ${\mathrm{cm}}^{\ensuremath{-}1}$.