Many-body renormalization of semiconductor quantum wire excitons: Absorption, gain, binding, and unbinding

We consider theoretically the formation and stability of quasi-one-dimensional many-body excitons in GaAs quantum wire structures under external photoexcitation conditions by solving the dynamically screened Bethe-Salpeter equation for realistic Coulomb interaction. In agreement with several recent experimental findings the calculated excitonic peak shows weak carrier-density dependence up to (and even above) the Mott transition density, n(c) similar to 3 x 10(5) cm(-1). Above n(c) we find considerable optical gain demonstrating compellingly the possibility of a one-dimensional quantum wire laser operation.