MOLECULAR-BEAM-EPITAXIAL GROWTH OF N-ALGAAS ON CLEAN CL-2-GAS ETCHED GAAS-SURFACES AND THE FORMATION OF HIGH MOBILITY 2-DIMENSIONAL ELECTRON-GAS AT THE ETCH-REGROWN INTERFACES

By using an ultrahigh vacuum multichamber process system, very clean GaAs surface is successfully prepared by chlorine-gas etching and AlGaAs is subsequently grown by molecular beam epitaxy to show that two-dimensional electron gas is successfully formed at etch-regrown AlGaAs/GaAs interface. Mobility as high as 114000 cm2/Vs at 9.8 K is achieved for the carrier concentration N(S)=4.5 X 10(11) CM-2 . From the secondary-ion-mass-spectroscopy measurement, the carbon concentration at the interface is estimated to be 2 X 10(10) CM-2, and is found to be a dominant scatterer for the two-dimensional electrons. A transmission-electron-microscope image has evidenced a very flat feature of etch-regrown interface.