SELECTIVE AREA 2-DIMENSIONAL ELECTRON-GAS STRUCTURES AND INSITU OHMIC CONTACTS PATTERNED BY FOCUSED ION-BEAM DOPING DURING MOLECULAR-BEAM EPITAXIAL-GROWTH

For the first time, the technique of low energy focused ion beam (FIB) doping during molecular beam epitaxial (MBE) growth has been used to grow GaAs/AlGaAs based structures with three-dimensionally patterned doping profiles. Two applications are described. Selective area Sn ion doped two-dimensional electron gas (2DEG) structures were grown with a 1.2 K mobility of 200,000 cm2 V-1 s-1 at a carrier concentration of 1 X 10(11) cm-2. Further, selective area highly doped regions were patterned in situ to form low temperature, low resistance ohmic contacts to the 2DEG of conventional HEMT structures doped with a thermal Si source. The effects of Sn diffusion and ion beam damage were investigated in these structures.