Selective area heteroepitaxy of low dislocation density antiphase boundary free GaAs microridges on flat-bottom (001) Si for integrated silicon photonics

Applied Physics Letters, Volume 118, Issue 12, March 2021. Integrating III–V gain elements in the silicon photonics platform via selective area heteroepitaxy (SAH) would enable large-scale and low-cost photonic integrated circuits. Here, we demonstrate antiphase boundary (APB)-free gallium arsenide (GaAs) microridges selectively grown on flat-bottom (001) silicon (Si) inside a recess. This approach eliminates the need for etching the patterned Si to form trapezoid or v-groove shapes, often leveraged for eliminating APBs. A low surface dislocation density of 8.5 × 106 cm−2 was achieved for 15-μm-wide GaAs microridges, quantified by electron channeling contrast imaging. The avoidance of APBs is primarily due to their self-annihilation, influenced by the sufficiently low temperature GaAs nucleation and subsequent higher temperature buffer overgrowth. Dislocation filtering approaches, namely, thermal cycle annealing and strained-layer superlattices, have been applied to effectively reduce the dislocation density. SAH of GaAs on trapezoidal-shaped Si pockets is also reported to illustrate the differing growth conditions for GaAs on (001) and (111) Si microplanes.