High quality GaAs epitaxially grown on Si(001) substrate through AlAs nucleation and thermal cycle annealing

Abstract

High quality GaAs was epitaxially grown on silicon(001) substrate through a hybrid technique of metalorganic chemical vapor deposition. The hybrid technique was comprised of AlAs nucleation and thermal cycle annealing to take advantages of both methods. The AlAs nucleation improved the surface roughness of GaAs buffer and the thermal cycle annealing reduced the threading dislocation (TD) density of GaAs buffer with small thickness. The GaAs buffer was grown with two-step growth with changing growth temperature and thermal cycle annealing processes. The optimal thickness of AlAs nucleation was determined to be 1.68 nm through systematic study with a series of buffer samples with different AlAs thicknesses. The TD density and surface roughness of GaAs buffer was quantitatively studied through electron channeling contrast imaging and atomic force microscopy, respectively. The growth temperature of GaAs buffer was also optimized to minimize the TD density. High quality GaAs buffer on Si(001) was obtained with a TD density 5.45 × 107 cm−2 with smooth surfaces. The total thickness of the buffer was approximately as thin as 1.5 μm. This study demonstrated a solution for silicon-based laser diodes to fulfill the monolithic integration of III-V on a Si platform.