Surface segregation of boron in BxGa1-xAs/GaAs epilayers studied by x-ray photoelectron spectroscopy and atomic force microscopy

The behavior of boron incorporation into GaAs has been studied by x-ray photoelectron spectroscopy, x-ray diffraction, and atomic force microscopy. As the boron content of the film was increased, both the characteristic peak for the B 1s core level at 188 eV and As Auger transition (260 eV) could be detected by XPS. At 550-600 degreesC, single crystalline films could only be grown for xless than or equal to0.06. Upon increasing the diborane flux in the gas phase, the film stoichiometry and the boron surface composition evolved rapidly towards a boron-rich subarsenide compound. This trend is followed by a clear degradation of the surface morphology and an increase in the surface roughness. A surface segregation of boron is suggested due to the high diborane vapor supersaturation needed during growth. (C) 2003 American Institute of Physics.