Role of molecular beam epitaxy parameters on InGaAs surface roughness

The effects of various growth parameters such as growth temperature (410-560 degreesC), indium composition (18%-36%), and growth front (GaAs or AlGaAs) on the InGaAs layer surface morphology, the room-mean-squared surface roughness (rrms value), and the microstructure are systematically reported. Atomic force microscopy (AFM) analysis of 12 nm thick In0.2Ga0.8As grwon on GaAs demonstrates a vey smooth surface with average rrms of similar to3.5 Angstrom. Within the temperature range of 410-440 degreesC, there is no trend or rrms change observed, which indicates that the growth temperature in this range is not a sensitive factor to the formation of In0.2Ga0.8As surface roughness. AFM images of 12 nm thick In0.2Ga0.8As grown on Al0.2Ga0.8As clearly show the initial formation of the InGaAs surface waves on GaAs at high resolution x-ray diffraction (HRXRD) analysis of the In0.23Ga0.77As grwon on GaAs at 520 degreesC indicates a nice crystal lattice match of the InGaAs to the GaAs surface. InGaAs with nominal 36% indium grown at 560 degreesC results in the disappearance of the InGaAs peak from HRXRD. (C) 2001 American Vacuum Society.