Optoelectronic device performance on reduced threading dislocation density GaAs/Si

A technique for the heteroepitaxy of GaAs/Si films having reduced threading dislocation density is presented. The important attribute of this technique is the suppression of three-dimensional Volmer–Weber island formation during initial deposition. This suppression is achieved by deposition of a stoichiometric GaAs buffer layer by a migration-enhanced epitaxy technique on silicon at 348 K to a thickness greater than the “monolithic thickness,” $h_m.$ Subsequent GaAs films deposited by conventional molecular beam epitaxy on buffer layers of thickness greater than $h_m$ possess structural and optical characteristics that exceed those for state-of-the-art GaAs/Si layers: an x-ray full width at half maximum (FWHM) of 110 arcsec with a dislocation density at the film surface of ${\text{3×10}}^6 {\mathrm{cm}}^{\mathrm{-2}}$ and a concomitant 4 K photoluminescence FWHM of 2.1 meV. The p-i-n structures suitable for use as light-emitting diodes (LEDs) that were grown on the reduced threading dislocation density GaAs/Si and by means of forward- and reverse-bias measurements, demonstrated an ideality factor of $\text{n=1.5,}$ an increased reverse-bias breakdown electric field of ${\text{2.1×10}}^7 \mathrm{V/m},$ and an intrinsic region resistivity of ${\text{4×10}}^7\mathrm{ \Omega }\mathrm{cm}$ for LEDs of increasingly smaller mesa size.