Experimental Determination of the Density Dependence of Electron-Hole Correlation in Electron-Hole Liquid

We report measurements of total lifetime and e-h pair density of electron-hole liquid in Ge under $〈111〉$ uniaxial stress. We show that the density dependence of electron-hole correlation can be estimated semiquantitatively from our data. Our result gives the first experimental evidence that electron-hole correlation increases rapidly as the e-h pair density is lowered. We compare our results with calculations based on different many-body theoretical approximations.