Recombination kinetics and intersubband relaxation in semiconductor quantum wires

Abstract

We present a detailed and systematic investigation of carrier capture, relaxation, cooling and radiative recombination in a one-dimensional semiconductor quantum wire of high structural perfection and optical quality over a large range of excitation (carrier) densities. Experimental evidence for a complete lack of 1D bandgap renormalization is found. Even u p to high carrier densities, > 106cm-', where strong band filling is already present and directly visible in the luminescence, no shift of bandgap to low energy is found. The carrier cooling in I D is appreciably slower than in comparable 2D structures, t h u s leading to high carrier temperatures. This confirms theoretical predictions of reduced phonon scattering probability in one-dimensional structures. The temoerature deoendence of the radiative lifetime of the 1D carriers is investigated. The theoretically predicted ,,6 dependence is not found. On the contrary an empirical = 0.02 T n s K -' law is fulfilled.

Coulomb Correlation and Band Gap Renormalization at High Carrier Densities in Quantum Wires

“…The common procedure of computing the optical gain using a 1͞ p E density of states is, however, incomplete as a number of effects such as inhomogeneities, Coulomb interactions, and many body effects are neglected. A better understanding of the recombination of a dense e-h plasma in QWRs is thus called for, and the subject has attracted considerable attention of late [4,[12][13][14][15][16].Recent progress in the growth of semiconductor nanostructures has made available wires of good quality which should open the way for rigorous studies that probe the different interactions that occur in quasi-1D systems. It is then unfortunate that the picture that emerges from the published literature on high density phenomena in QWRs is confused and contradictory.…”

Real-Space Transfer and Trapping of Carriers into Single GaAs Quantum Wires Studied by Near-Field Optical Spectroscopy

“…Furthermore, processes involving realspace transfer of carriers are difficult to separate from carrier relaxation in the QWR. This is particularly relevant for carrier capture into a QWR where-in general-both real-space transfer in delocalized states and trapping at the QWR location occur [5][6][7]. Until now, a clear separation of such processes, which is essential for understanding the underlying physics, has not been possible.…”

“…Both cathodoluminescence [5,6] and near-field scanning optical microscopy (NSOM) [8,9] have been applied to investigate single quantum wires, in the case of NSOM with energetically well-defined excitation. In this Letter, we present the first near-field optical study of real-space transfer and capture of carriers into a single GaAs quantum wire.…”

Self-ordering and confinement in strained InGaAs/AlGaAs V-groove quantum wires grown by low-pressure organometallic chemical vapor deposition

“…The luminescence peak energies of the different QWR subbands present virtually no shift (Ͻ2 meV) when the current is increased between 0.1 and 100 nA ͑the corresponding estimated carrier densities are n ϳ2ϫ10 4 cm Ϫ1 and nϳ10 7 cm Ϫ1 , respectively͒. Essentially the same effect was observed in similar GaAs/AlGaAs QWR structures 14 and was interpreted as being due to the enhanced stability of excitons in QWRs. 15 Shifts below 1 meV were also observed in unstrained GaAs/AlGaAs QWRs; they were explained as being due to disorder effects along the wire.…”