Electronic structure and absorption spectrum of biexciton obtained by using exciton basis

Abstract

We approach the biexciton Schrödinger equation not through the free-carrier basis as usually done, but through the free-exciton basis, exciton-exciton interactions being treated according to the recently developed composite boson many-body formalism which allows an exact handling of carrier exchange between excitons, as induced by the Pauli exclusion principle. We numerically solve the resulting biexciton Schrödinger equation with the exciton levels restricted to the ground state and we derive the biexciton ground state as well as the bound and unbound excited states as a function of hole-to-electron mass ratio. The biexciton ground-state energy we find, agrees reasonably well with variational results. Next, we use the obtained biexciton wave functions to calculate optical absorption in the presence of a dilute exciton gas in quantum well. We find a small asymmetric peak with a characteristic low-energy tail, identified with the biexciton ground state, and a set of large peaks associated with biexciton unbound states, i.e., exciton-exciton scattering states.

Excitonic effects in two-dimensional semiconductors: Path integral Monte Carlo approach

“…( 6). In the case of a trion or biexciton, the exact analytical expression for E δ (σ, 0) is not available, but multiple approximate analytical, as well as approximate numerical and numerically exact results have been obtained to date [44,49,[56][57][58][59][60][61][62][63][64][65].…”

Thermodynamic Equilibrium between Excitons and Excitonic Molecules Dictates Optical Gain in Colloidal CdSe Quantum Wells

“…38,39 This amounts to ∼43 meV in the case of the CdSe CQWs studied here, a value corresponding to the PA region in the transient absorbance map. Because a stable molecule should only be formed in a singlet state with total angular momentum F = 0 for zinc-blende CdSe, 40,41 the possible formation of molecules can be verified through circularly polarized pump−probe spectroscopy. 12 As indicated in Figure 3a, a σ + σ − sequence of right-handed pump and left-handed probe light can create molecules, and so does a σ − σ + sequence, whereas σ + σ + or σ − σ − sequences cannot.…”

Correlated-pair approach to composite-boson scattering lengths

“…Figure 3 shows the numerically obtained renormalized fermionic-atom dimer-dimer scatteringζ(K, 0), as well aŝ ζ (sep) (K, 0) obtained from Eq. (29). Agreement is very good for all mass ratios, except for some minor discrepancy near Ka ∼ 2 when m β /m α ≥ 100.…”