The effect of As-4 pressure on material qualities of AlGaAs/GaAs heterostructures grown on (111)B GaAs substrates

High-quality AlGaAs/GaAs heterostructures have been grown on on-axis (111)B GaAs substrates using molecular-beam epitaxy to study the effect of As-4 p ressure on the material qualities. It was found that the electrical and str uctural properties were strongly dependent on the As-4 pressure. The qualit y of the heterostructure was investigated by Hall effect, atomic force micr oscopy, and high-resolution x-ray diffraction measurements. The electron Ha ll mobility dropped from 7200 and 90 000 cm(2)/V s to 930 and 1340 cm(2)/V s at room temperature and 77 K, respectively, as As-4 pressure was increase d from 4.9x10(-6) to 1.1x10(-7) Torr. The same trend was observed at the ro ot-mean-square roughness of the AlGaAs/GaAs heterostructures measured by at omic force microscopy, and the intensity and full width at half-maximum of the x-ray diffraction curve. (C) 2000 American Institute of Physics. [S0003 -6951(00)00543-X].