Strain-Confined Electron-Hole Liquld in Germanium

J. P. Wolfe ； R. S. Markiewicz

《Chinese Journal of Physics》 15卷2期 (1977/07) Pp. 124-131

並列摘要

Previous experiments in pure germanium at low temperature have shown that high densities of photo-produced electron-hole pairs condense into a metallic liquid phase-typically manifested as small electron-hole droplets (EHD). The energy, pair density, and lifetime of an EHD can be significantly modified by applying a stress to the crystal. Due to the lowering of the indirect band edge with strain, droplets, free excitons, and carriers are accelerated in a strain gradient approximately towards a point of maximum shear strain. By appropriately stressing a crystal, it is possible to create inside the crystal a shear strain maximum, i.e., a potential well, into which droplets, excitons and carriers are attracted, causing them to coalesce into a macroscopic mass of electron-hole liquid with diameter up to a millimeter. The existence of these large drops is supported by a number of experiments. to be discussed in this talk: 1) Alfven wave resonances are observed by microwave absorption in applied fields HZ20 hoe. 2) Time-resolved luminescence studies of a drop in stressed Ge uncover a 10×longer EHD lifetime than in unstressed Ge. 3) Photographic images of an EHD obtained with an infraerd sensitive vidicon show the position of the strain-confined liquid in the crystal.