Linear polarization of photoluminescence emission and absorption in quantum-well wire structures: Experiment and theory

The photoluminescence (PL) and photoluminescence excitation (PLE) spectra of ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum-well wires (QWW’s) with wire widths ${\mathit{L}}_{\mathit{x}}$ between 10 nm and 1 μm have been found to demonstrate a strong linear polarization parallel to the wires. The polarization is proportional to 1/${\mathit{L}}_{\mathit{x}}$ for broad wires and saturates in the case of narrow wires at a level of 20–60 % depending on the QWW structure design. This effect in PL and band-edge PLE transitions is shown to be mainly due to the modification of the electromagnetic-field eigenmodes in the vicinity of the quantum wires.