Molecular-beam-epitaxial growth of n-AlGaAs on clean Cl2-gas etched GaAs surfaces and the formation of high mobility two-dimensional electron gas at the etch-regrown interfaces

Abstract

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 114 000 cm²/V s at 9.8 K is achieved for the carrier concentration N_S=4.5×10¹¹ cm⁻². From the secondary‐ion‐mass‐spectroscopy measurement, the carbon concentration at the interface is estimated to be 2×10¹⁰ 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.