Multicomponent Electron–Hole Liquid in Si/SiGe Quantum Wells

The density functional theory is used to calculate the energy of an electron–hole liquid in Si/Si1–xGex/Si quantum wells. Three one-dimensional nonlinear Schrödinger equations for electrons and light and heavy holes are solved numerically. It is shown that, in shallow quantum wells (small x), both light and heavy holes exist in the electron–hole liquid. Upon an increase in the Ge content, a transition to a state with one type of holes occurs, with the equilibrium density of electron–hole pairs decreasing by more than a factor of 2.