Mid-infrared InAs/InAsSb Type-II superlattices grown on silicon by MOCVD

In this work we report the growth of the InAs/InAsSb type-II superlattice (T2SL) onto Si substrates via the use of a GaSb/GaAs/Si buffer layer structure all grown by MOCVD. Transmission electron microscopy (TEM) was used to show the effectiveness of the buffer layer structure in reducing threading dislocation density and to verify the formation of an interfacial misfit dislocation array between the GaSb and GaAs layers. Electron channelling contrast imaging was used to measure a threading dislocation density of 6.73 × 108/cm2 at the surface of the T2SL. TEM and X-ray diffraction show that the T2SL itself was grown to a high quality considering the large mismatch of the heteroepitaxy. Fourier transform infrared spectroscopy was used to measure the photoluminescence performance of the T2SL which was found to have a FWHM of 50 meV at a peak wavelength of 4.5 µm at 77 K. These results are a step forward towards integration of full InAs/InAsSb T2SL device structures onto Si substrates via MOCVD.