Surface and Interface Properties of Quantum Nanostructures Grown on Nonplanar Substrates

The surface and interface properties of self-ordered quantum well, quantum wire and quantum dot GaAs/AlGaAs and InGaAs/AlGaAs structures grown by low pressure organometallic chemical vapor deposition (OMCVD) on V-grooved substrates are described. Transmission electron microscopy as well as cross sectional and top atomic force microscopy in air are employed to investigate the self ordering mechanisms of these nanostructures. OMCVD on the patterned substrates leads to step-flow growth with monolayer steps oriented perpendicular to the grove edges and to self-ordered nanofacets at the bottom of the grooves. These ordered, patterned surfaces form the basis for the formation of AlGaAs and InGaAs quantum wells and quantum wires whose size and shape are determined by the composition and the growth conditions. The top surfaces of the V-groove quantum wires reveal quasi-periodic facet undulations, suggesting the formation of ordered, dot-like structures providing three-dimensional quantum confinement.