INSITU 2-DIMENSIONAL ELECTRON-GAS FABRICATION BY FOCUSED SI ION-BEAM IMPLANTATION AND MOLECULAR-BEAM EPITAXY OVERGROWTH

We have demonstrated the possibility of in situ two-dimensional electron gas (2DEG) fabrication in GaAs/AlGaAs heterostructures, using focused ion beam implanter and molecular beam epitaxy (FIBI-MBE) crystal growth system. 2DEGs are formed in a GaAs channel layer which is overgrown on an AlGaAs electron supply layer implanted selectivity with Si-FIBs. Implanted Si atoms are activated by rapid thermal annealing (RTA). We confirmed 2DEG formation by Shubnikov-de Haas oscillation. We clarified the influence of ion implantation damage on the quality of overgrown epilayers and obtained an extremely high 2DEG mobility of 32 000 cm2/V s at 77 K and 48 000 cm2/V s at 20 K. We also discussed possible quantum-size doping by direct FIB implantation, considering the lateral scattering of incident Si ions in the substrate.