Lateral quantization effects in the optical spectra of InGaAs/GaAs quantum wires

We have investigated low and high density luminescence spectra of modulated barrier InGaAs/GaAs quantum wires with widths down to the 20 nm range. In this approach a lateral confinement is obtained by selective removal of the GaAs cap layer in the barrier regions between the wires. As the InGaAs layer containing the wires serves also as a lateral barrier the influence of nonradiative recombination in the etched structures is significantly reduced. High excitation luminescence experiments show a clear band filling of the structures already at remarkably low excitation intensities and reveal different lateral subband transitions. In sufficiently high magnetic fields a transition from size quantization to Landau quantization is observed.