  We present a theoretical investigation of high-harmonic generation (HHG) from
impurity-doped materials using the time-dependent Schr\"odinger equation (TDSE)
approach. We demonstrate the factorization of HHG yields as a product of an
electron wave packet and the recombination cross section, in analogy to HHG
from atoms and molecules in the gas phase. Furthermore, we show that the
quantitative rescattering model based on this factorization accurately
reproduces the TDSE results. This opens up new possibilities to study
impurities in materials using the available techniques from strong-field
physics.
