Growth and characterization of midinfrared InGaAs/InAlAs strained triplequantumwell lightemitting diodes grown on latticemismatched GaAs substrates

With chemical beam epitaxy we stacked small InAs islands, separated by thin GaAs layers. Reflection electron diffraction during growth showed that after a seed-layer growth, subsequent depositions require less InAs to form the islands. At 5 K the stacks have narrower luminescence peaks at lower energies than single island layers, and the stacks luminesce at room temperature. For 4-nm-high pyramidal islands with 20-nm-wide bases, we observed vertical periods down to 5.4 nm, small enough to couple quantum mechanically. The electronic structures possible for this class of objects should be sufficient for designing and observing room temperature quantum mechanical phenomena.