Magneto-Acoustical Properties of a Large Electron-Hole Drop in Stressed Germanium

Abstract

With pulse-echo technique we have measured magneto-acoustic attenuation by a large electron-hole drop in stressed Ge at the temperature range 1.7 to 4.2 K. The scattering rate for electrons and the electron-hole pair density in a large drop are determined by numerical fitting of an appropriate theory to the experimental data. It is found that the carrier-carrier scattering is a dominant contribution to the carrier relaxation. The pair density decreases with increasing temperature because of thermal expansion of the drop. Little change in pair density is observed as the radius of the drop shrinks. In the geometry of B⁄⁄⟨110⟩, a striking increase in pair density is confirmed for B>3 T. This effect has never been observed for the large drop.