Exploring the Effectsof Hydrogen on the Growth andProperties of GaN Nanowires Using VLS-HVPE

In this study, gallium nitride (GaN) nanowires were successfully synthesized via the vapor–liquid–solid mechanism within a hydride vapor phase epitaxy technique on different substrates. By optimizing the growth conditions with hydrogen as an additional carrier gas, we found that the morphology of GaN nanowires was significantly altered from wire-like to rod-like compared to the conventional method using nitrogen alone. The optical quality of as-grown nanowires was enhanced, demonstrated by a marked photoluminescence (PL) peak at the near-band edge of GaN and a distinct reduction in defect-related PL yellow emissions. These effects were especially notable in the nanowires grown on MoS₂ substrates, which are promising candidates for future electronic devices. Scanning transmission electron microscopy revealed the significant influence of hydrogen on the microstructure and orientation of the nanowires. Energy dispersive X-ray spectroscopy analysis indicated that the gallium concentration at the nanowire tips, also called the catalyst, varies with the two types of growth orientation. Furthermore, the GaN nanowires grown on MoS₂ exhibit enhanced piezoelectric properties compared to previous reports due to the growth orientation control. These findings highlight the production of high-quality GaN nanowires and offer valuable insights into the role of hydrogen in influencing the growth dynamics.