On the Instability of the Electron–Hole System in Coupled Quantum Wells

It is shown that the homogeneous state of the spatially separated electrons and holes in coupled quantum wells (CQW) is instable if the layer charge density is smaller than the critical value nc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$n_{c}$$\end{document} specified by the parameters of the CQW. The effect is due to the many-body Coulomb correlations that provide the positive compressibility. The instability results in the formation of the inhomogeneous system that comprises the liquid electron–hole drops.