Microwave Phonon Attenuation Measurements inn-Type Silicon

Microwave phonon attenuation at 9.3 GHz in $n$-type silicon has been measured between 2 and 100 K. The excess attenuation observed in impure samples is attributed to conduction electrons. The intervalley relaxation time is determined from these results for Sb- and As-doped silicon with impurity concentration between 3 × ${10}^{17}$ and 2 × ${10}^{19}$ ${\mathrm{cm}}^{-3\mathrm{}}$. A large excess attenuation, not accounted for by any existing theories, is observed at low temperatures in nondegenerate samples. The discrepancy between experiment and theory is thought to arise from electrons in impurity states. It is suggested that hopping conduction may explain our results at low temperatures. No specific influence of impurity band formation on attenuation is found experimentally.