Layer-compensated selectively doped AlxGa1-xAs/GaAs heterostructures as a base material for nanolithography

Selectively n-doped AlxGa1-xAs/GaAs heterostructures with an additional p-t ype doped GaAs compensation layer on top were prepared by solid-source mole cular beam epitaxy. If properly designed, these layer-compensated heterostr uctures are not conducting with the compensation layer present, whereas a t wo-dimensional electron gas (2DEG) is formed at the heterointerface if the compensation layer is removed. This makes the material well suited as a bas e material for nanolithography because lateral patterning of the compensati on layer results in a laterally structured 2DEG. We found by simulation as well as experimentally that the n-type delta doping concentration is very c ritical and has to be correct within +/-15% to obtain properly compensated heterostructures. For the non-compensated case, i.e. with the compensation layer removed, electron densities up to 4.3 x 10(11) cm(-2) before illumina tion and 9 x 10(11) cm(-2) after illumination have been achieved in structu res that are insulating with a compensation layer. The obtained electron mo bilities in the 2DEG are high, reaching a maximum value of 1.1 x 10(6) cm(2 ) V-1 s(-1) at 4.2 K after illumination.