In memory of Leonid Veniaminovich Keldysh. Reviews of topical problems
Electron-hole liquid in semiconductors and low-dimensional structures
N.N. Sibeldin Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prosp. 53, Moscow, 119991, Russian Federation
The condensation of excitons into an electron-hole liquid (EHL) and the main EHL properties in bulk semiconductors and low-dimensional structures are considered. The EHL properties in bulk materials are discussed primarily in qualitative terms based on the experimental results obtained for germanium and silicon. Some of the experiments in which the main EHL thermodynamic parameters (density and binding energy) have been obtained are described and the basic factors that determine these parameters are considered. Topics covered include the effect of external perturbations (uniaxial strain and magnetic field) on EHL stability; phase diagrams for a nonequilibrium exciton gas—EHL system; information on the size and concentration of EHL drops (EHDs) under various experimental conditions; the kinetics of exciton condensation and of recombination in the exciton gas—EHD system; dynamic EHD properties and the motion of EHDs under the action of external forces; the properties of giant EHDs that form in potential wells produced by applying an inhomogeneous strain to the crystal; effects associated with the drag of EHDs by nonequilibrium phonons (phonon wind), including the dynamics and formation of the anisotropic spatial structure of the EHD cloud. In discussing EHL in low-dimensional structures, a number of studies are reviewed on the observation and experimental investigation of such phenomena as spatially indirect (dipolar) electron-hole and exciton (dielectric) liquids in GaAs/AlGaAs structures with double quantum wells (QWs), EHDs containing just a few electron-hole pairs (dropletons), EHL in type-I silicon QWs, and spatially direct and dipolar EHLs in type-II silicon-germanium heterostructures.
Keywords: excitons, electron-hole liquid, density, binding energy, stability, phase diagram, thermodynamic parameters, electron-hole drops, drop size and concentration, condensation kinetics, recombination kinetics, drop motion, giant drops, phonon wind, drag effect, drop cloud, spatial structure of drop cloud, dynamics of drop cloud, strain field, magnetic field, low-dimensional structures, quantum wells, electron-hole bilayers, spatially direct and dipolar excitons, spatially direct and dipolar liquids, dropletons. PACS:71.35.−y, 73.20.Mf, 73.21.−b (all) DOI:10.3367/UFNe.2017.08.038194 URL: https://ufn.ru/en/articles/2017/11/e/ Citation: Sibeldin N N "Electron-hole liquid in semiconductors and low-dimensional structures" Phys. Usp.60 1147–1179 (2017)