Observation of electronic subbands in dense arrays of quantum wires grown by organometallic-chemical-vapor deposition on nonplanar substrates

We report luminescence and adsorption properties of dense arrays of narrow (14-nm), crescent-shaped GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wires (QWR’s) grown by organometallic chemical vapor deposition on nonplanar substrates. Low-temperature photoluminescence (PL) spectra of the samples are dominated by emission from the QWR’s, indicating efficient carrier transfer into the wires from the surrounding quantum wells and barriers. PL excitation spectra of the wires exhibit enhanced absorption at the electron–heavy-hole subbands with a measured subband separation of 34–39 meV, in good agreement with calculated values. Achievement of such large subband separations, on the order of ${\mathit{k}}_{\mathit{B}}$T at room temperature (for electrons), is important for investigations of quasi-one-dimensional systems in which only the ground state of the QWR is populated.