The electron-hole liquid in semiconductors

Abstract In highly excited semiconductors at low enough temperatures nonequilibrium electrons, holes and excitons condense into droplets of a metallic degenerate Fermi liquid, the so called electron-hole liquid. General properties of this new quantum liquid are reviewed including possible types of its phase diagram; the strong dependence of the phase diagram on the band and crystalline structure of the semiconductor, magnetic field etc.; the kinetics of electron-hole drop nucleation, growth and decay. Electron-hole drops can easily be accelerated by some external forces up to velocities close to that of sound. Intense movement of drops also occurs because of the so called phonon wind-drag by intense flows of nonequilibrium phonons, arising in recombination processes inside the drops themselves or in the therrnalization of excited carriers.