Electrical and structural studies of AlGaAs/GaAs wires grown on patterned substrates

The electrical and structural properties of U- and V-shaped Al(0.3)Ga(0.7)As/GaAs wire structures grown by low-pressure metal-organic vapor phase epitaxy were investigated. By using dimethylethylamine alane (DMEAA) and triethylgallium (TEGa) for the growth of the bottom Al(0.3)Ga(0.7)As buffer layer, a non-conductive, polycrystalline layer is formed on top of the SiO(2) masked areas, leading to an effective electrical isolation between adjacent wire structures. The characterization of the morphology by TEM confirmed the formation of a wire structure at the bottom of the V-groove. Additionally, it was observed that if DMEAA/TEGa is used as a source for the growth of the lower Al(0.3)Ga(0.7)As barrier layer, the radius of curvature of the crescent-shaped quantum wires at bottom of the V-shaped groove is larger than in structures where this barrier layer is based on trimethylaluminum and trimethylgallium sources. From magneto-transport measurements under different orientations of the magnetic field it could be concluded that in U-shaped structures, the main conductive channel is located at the (100) bottom layer, while for the V-shaped structures the side-wall quantum well and the quantum wire contribute to the conductance. (C) 1998 Elsevier Science B.V.