Direct magneto-optical observation of a quantum confined one-dimensional electron gas

The energy spectra of isolated one-dimensional (1D) electron channels have been studied by photoluminescence in zero and finite magnetic fields B. Arrays of periodic quantum wires (period =290–400 nm, width =150–170 nm) were etched from modulation-doped ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs heterojunctions, with special low-concentration Be δ doping in the buffer layer to increase the photoluminescence intensity. We were able to attain the 1D quantum limit, i.e., occupation of only the lowest 1D subband at B=0, and to measure, at small B, a characteristic quadratic B dispersion of the 1D subband edge.