Nanoscale and Alloy Engineering of III-Nitride Semiconductors for High-Efficiency Solar Photocatalysis and Optoelectronics

Passcode: 784388

GaN-based nanostructures are increasingly being used for a broad range of electronic and photonic device applications including artificial photosynthesis. Solar water splitting has become a promising means of renewable hydrogen-fuel production and III-Nitride semiconductors are suitable for such applications due to their tunable direct energy band gaps and structural stability. In this work, we investigate the design, synthesis, and characterization of GaN/InGaN-based nano as well as deep-nano structures for artificial photosynthesis and optoelectronic applications.

Conventional semiconducting nanowire optoelectronic devices generally exhibit low efficiency due to dominant nonradiative surface recombination. Such a critical challenge was addressed by exploiting semiconductors in the deep-nano regime and nearly two orders of magnitude reduction in the surface recombination velocity was observed, evidenced by the extremely bright luminescence emission and long carrier lifetime. Detailed investigation on the charge carrier dynamics and photocatalysis of Mg-doped p-type InGaN deep-nano structures was also performed. Subsequently, a unique strategy to overcome the efficiency bottleneck of photocatalytic water splitting was developed with GaN/InGaN-based nanowire photocatalyst using the synergistic effects of promoting forward hydrogen-oxygen evolution and inhibiting the reverse hydrogen-oxygen recombination by operating at an optimal reaction temperature. Furthermore, a novel photocatalyst protection architecture was designed comprising a dynamic oxide layer to achieve remarkably longer photocatalytic stability by simultaneously mitigating photocatalytic corrosion and cocatalyst nanoparticle displacement.

Overall, this work provides significant insights into developing the next-generation of high-efficiency nanoscale optoelectronic and artificial photosynthesis devices.

Chair: Professor Zetian Mi