Abstract:

The MBE growth of Inx Ga11-xAs (x~0.53) on silicon substrates has been investigated emphasizing the effects of substrate orientation and buffer layers between In0.53Ga0.47As and Si.  It is shown that growth on silicon substrates misoriented from (001) toward a [110] direction eliminates the presence of antiphase domains.  The best In0.53 Ga As surface morphology was obtained when a 0.9 Mm eptaxial Si buffer was initially grown, followed by a pre-exposure of the silicon surface to As4 at 350ºC, followed by the growth of In0.53 Ga0.47As.  Threading dislocations, stacking faults, low-angle grain boundaries, and spinodal contrast scale was shown to depend on the buffer type and the total InGaAs thickness.  Thick buffers consisted of GaAs or graded Inx Ga1-x As layers, and large In0.53Ga0.47 As thicknesses favor the development of a coarse-scale spinodal decomposition with periodicity around 0.1 Mm.  Thin GaAs buffers or direct In 0.53 Ga 0.47 growth on Si may result in a fine-scale decomposition of periodicity ~10 nm.  The principal strain direction of the spinodal decomposition appeared along the [110] direction, parallel to the vicinal Si surface step edges.  IngaAs immiscibility affects the InGaAs growth process, favoring a 3-D growth mode.  X-ray diffraction measurements and photo-reflectance spectra indicated that the sample quality was improved for samples exhibiting a fine-scale spinodal decomposition contrast even if they contained a higher dislocation density.  Threading dislocations run almost parallel to the [001] growth axis and are not affected by strained layers and short period (InAs)3/(GaAs)3 super-lattices.  The lowest double crystal diffractometry FWHM for the (004) InGaAs reflection was 720 arc sec and has been obtained growing InGaAs directly on Si, while the lowest dislocation density was 3 x 109 cm-2 and was obtained using a 1.5 Mm GaAs buffer before the In0.53Ga0.47As deposition.