Evolution of excitons via biexcitons to an electron-hole plasma without level crossing between band edge and exciton in a quantum wire

Original · EN

A recent single quantum wire is of sufficient quality to reveal new details of the photoluminescence (PL) evolution with increasing electron--hole (e--h) pair density. At a pair density of 3.6 × 10³ cm⁻¹, the PL is characteristic of biexcitons shifted below the exciton peak by the 2.8-meV biexciton binding. At the pair density of 1.2 × 10⁵ cm⁻¹, the biexciton peak broadens without energy shift to an e--h plasma. At all pair densities up to 30 K, neither the exciton peak nor the one-dimensional (1D) continuum edge shows any shift. In contrast to prevailing theories, the low-energy edge of the plasma PL line never crosses the exciton peak and never makes contact with the 1D e--h continuum.