A novel technique to make Ohmic contact to a buried two-dimensional electron gas in a molecular-beam-epitaxy grown $GaAs/Al_{0.3}Ga_{0.7}As$ heterostructure with Mn $delta$-doping

We report on the growth and characterization of a new Diluted Magnetic Semiconductor (DMS) heterostructure that presents a Two-Dimensional Electron Gas (2DEG) with a carrier density $n sim 1.08 times 10^{12} cm^{-2}$ and a mobility $mu sim 600 cm^{2} / (Vs)$ at T $sim$ 4.2K. As far as we know this is the highest mobility value reported in the literature for GaMnAs systems. A novel technique was developed to make Ohmic contact to the buried 2DEG without destroying the magnetic properties of our crystal.