Diffusion and phase diagram of an electron-hole bilayer: A molecular dynamics study

Molecular dynamics simulations of a classical, symmetric electron-hole bilayer for various values of the coupling strength Gamma and interlayer separation distance d have been performed. We have analyzed the pair correlation functions, the static structure factor, and the diffusion coefficient in this study. As d is decreased, diffusion goes through a minimum and then increases very rapidly; its behavior at small d can be attributed to the formation of stable, weakly interacting electron-hole dipoles. We have constructed the phase diagram in the Gamma-d plane based on the amplitude of the main peak of the intralayer static structure factor and the diffusion coefficient. It is found that a solid phase is not possible for d less than about 0.5 for any Gamma, nor for Gamma less than about 100 for any d. Our phase diagram, obtained using a different methodology, is in good agreement with the one in the literature.