Backward-wave phonon spectroscopy in Si: In

The resonant mixing of forward-propagating phonons with a microwave electric field in indium-doped silicon leads to the generation of backward-propagating phonons. The magnetic-field-frequency dependence of the backward-wave generation gives rise to a spectroscopic tool for the study of deep states in semiconductors, which partially overcomes the effects of inhomogeneoous broadening. © 1979 The American Physical Society.