Crystal Phase Control and Room-Temperature Random Lasing in Multiperiod GaAs/AlGaAs Axial Heterostructure Nanowires via Al-Mediated Catalyst Engineering

Semiconductor axial heterostructure nanowires (NWs) offer unique advantages for nanophotonics but face challenges in achieving high crystal phase uniformity due to nucleation instability during growth, which limits their optoelectronic performance. In this study, Al-mediated catalyst engineering has been demonstrated to be an effective strategy for crystal phase control in multiperiod GaAs/Al_0.4Ga_0.6As axial heterostructure NWs fabricated by molecular beam epitaxy. By systematically varying the GaAs segment growth times (30, 60, 90, and 120 s), it was determined that all samples exhibit distinctive lotus-root morphology, and the 90 s sample (GaAs-90) achieves quasi-pure zincblende (ZB) phase formation. This is attributed to Al incorporation, reducing the Ga droplet size and liquid-vapor surface energy, thereby stabilizing ZB nucleation. Optical characterization reveals that GaAs-90 achieves room-temperature random lasing with a threshold of 55.59 mW/cm². This study elucidates the critical synergy between crystal phase control and axial heterostructure design in achieving efficient NW random lasing, offering a scalable technological framework for on-chip integrated photonics.