Abstract
We report GaAs/(Al, Ga)As nanowires in the one-dimensional (1D) quantum limit. The ultrathin wurtzite GaAs cores between 20 and 40 nm induce large confinement energies of several tens of millielectronvolts, allowing us to experimentally resolve up to four well-separated subband excitations in microphotoluminescence spectroscopy. Our detailed experimental and theoretical polarization-resolved ...
Abstract
We report GaAs/(Al, Ga)As nanowires in the one-dimensional (1D) quantum limit. The ultrathin wurtzite GaAs cores between 20 and 40 nm induce large confinement energies of several tens of millielectronvolts, allowing us to experimentally resolve up to four well-separated subband excitations in microphotoluminescence spectroscopy. Our detailed experimental and theoretical polarization-resolved study reveals a strong diameter-dependent anisotropy of these transitions: We demonstrate that the polarization of the detected photoluminescence is governed, on the one hand, by the symmetry of the wurtzite 1D quantum wire subbands but also, on the other, by the dielectric mismatch of the wires with the surrounding material. The latter effect leads to a strong attenuation of perpendicularly polarized light in thin-dielectric wires, making the thickness of the (Al, Ga)As shell an important factor in the observed polarization behavior. Including the dielectric mismatch to our k center dot p-based simulated polarization-resolved spectra of purely wurtzite GaAs quantum wires, we find excellent agreement between experiment and theory. These findings reveal insights relevant to spectroscopic studies of the 1D quantum regime and the design of photonic quantum wire applications such as lasers and hopefully open up paths for selective subband excitations.
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