Microstructure and surface morphology of InAsSbBi grown by molecular beam epitaxy

The physical and chemical properties of 210nm thick InAsSbBi layers grown by molecular beam epitaxy at temperatures between 400 and 430 degrees C on (100) GaSb substrates are investigated using Rutherford backscattering, X-ray diffraction, transmission electron microscopy, Nomarski optical microscopy, and atomic force microscopy. The results indicate that the layers are nearly lattice matched, coherently strained, and contain dilute Bi mole fractions. Large surface droplets with diameters on the order of 1 mu m and densities on the order of 10(6)cm(-2) are observed when the InAsSbBi growth is performed with lean As overpressures around 1%. Surface droplets are not observed when the As overpressure is increased to 4%. Small crystalline droplets with diameters on the order of 70nm and densities on the order of 10(10)cm(-2) are observed between the large droplets for InAsSbBi grown at 430 degrees C. Analysis of one of the small droplets indicates a misoriented zinc blende crystal structure composed primarily of In, Sb, and Bi, with a lattice constant of 6.543 +/- 0.038 angstrom. Lateral modulation in the Bi mole fraction is observed in InAsSbBi layers grown at 400 degrees C.