Heteroepitaxial growth of GaSb interfacial misfit array on GaAs substrate by molecular beam epitaxy

Abstract

Heteroepitaxy growth of antimonide-based superlattices offers new opportunities for band structure engineering in infrared optoelectronics. Due to the wafer size limitations and cost of GaSb substrates, lattice − mismatched epitaxy of antimonide-based materials on GaAs substrates presents an attractive alternative with large wafer scales, low costs, and great ohmic contacts. Herein, we report a heterostructure growth method using molecular beam epitaxy based on the interfacial misfit (IMF) array technique. The 7.8% lattice mismatch at the GaAs/GaSb interface was accommodated through a thin low temperature (LT) nucleation layer followed by a thick high-temperature (HT) GaSb buffer layer. We explain the evolution of rectangular-like defects for direct growth GaSb on GaAs substrates. Under optimized GaAs/LT-GaSb/GaSb heterostructure growth conditions, we achieved highly smooth GaSb surfaces with well-defined atomic steps as observed in atomic force microscope (AFM) measurements. Furthermore, high-resolution X-ray diffraction (HRXRD) characterization reveals that misfit dislocations are dominated by 90° dislocations at the GaAs/GaSb interface. We obtained a full width at half maximum (FWHM) of 140.6 arcsec for a 2 μm thick GaSb layer on a GaAs substrate and achieved a high lattice relaxation of 99.7%. These results demonstrate that our proposed growth method holds great potential for achieving excellent surface morphology and high crystal quality in GaAs/GaSb heteroepitaxial system.