ULTRAHIGH MOBILITY 2-DIMENSIONAL ELECTRON-GAS IN ALXGA1-XAS/GAAS HETEROSTRUCTURES BY ORGANOMETALLIC VAPOR-PHASE EPITAXY

Ultrahigh mobility AlxGa1-xAs/GaAs two-dimensional electron gas (2DEG) structures were grown by conventional low-pressure organometallic vapor phase epitaxy (LP-OMVPE). We achieved maximum mobilities of 766 000 cm2/V s at 2.2 K and 171 000 cm2/V s at 77 K after exposure to light (to our knowledge, the highest ever by OMVPE growth), with a sheet carrier density of 4.9 X 10(11)/cm2. The high-mobility structures were obtained by either growing an AlGaAs-related buffer underneath the 2DEG structure or preconditioning of the reactor with an undoped AlGaAs run. The dark mobilities of samples grown with the preconditioning procedures and without the AlGaAs-related buffer are much higher than those with the buffer.