Ultrasound-stimulated increase in the electron diffusion length in p-Si crystals

The effect of ultrasound on the diffusion length of minority charge carriers in dislocation-free p-Si is investigated in the frequency range 0.8–5.5 MHz. The diffusion length is measured by the surface photovoltage method. It is found that the diffusion length reversibly increases (by a factor of two at a sound intensity of 3 W/cm²) in response to ultrasound. The dependences of the diffusion length on the ultrasound amplitude and the kinetic characteristics upon switching on and switching off the ultrasound are analyzed. The phenomena observed are explained within the proposed model of transformation of recombination centers under the effect of ultrasound.