Colloidal Crystallization of GaP, and III-V Heterostructures Using Low Valent Metal Precursors

With the support of the Macromolecular, Supramolecular and Nanochemistry Program, Professor Jonathan Owen of Columbia University is studying a new strategy to synthesize nanometer scale semiconductor crystals that convert blue light-emitting diode (LED) light into red emission. A “redox conversion” process will use low-valent gallium and indium precursors together with phosphorus and arsenic reagents to grow nanoscale particles in more widely accessible surfactant solution. If successful, this research will produce cadmium-free materials for energy-efficient lighting and infrared detectors, while training high school, undergraduate, and graduate students in cutting-edge synthesis and spectroscopy. With the support of the Macromolecular, Supramolecular and Nanochemistry Program, Professor Jonathan Owen of Columbia University is studying a novel colloidal synthesis strategy to prepare III–V quantum dot heterostructures with controlled crystallinity, size, and composition. GaP, GaAs, InGaP alloys, and InP/GaP core/shell architectures will be synthesized by pairing Ga(I) and In(I) complexes with tailored phosphine, phosphite, and phosphonium reagents. The resulting nanocrystals will be rigorously characterized by synchrotron X-ray total scattering and pair distribution function analysis, Raman spectroscopy, solid-state ³¹P Nuclear Magnetic Resonance, ultraviolet photoelectron spectroscopy, electron microscopy, and photoluminescence measurements to assess defect density, phase purity, electronic structure, and biexciton quantum yields. This effort will establish design rules for covalent semiconductor nanomaterials and demonstrate heterostructures with enhanced flux stability and reduced Auger recombination for solid state lighting, micro-LEDs, and infrared optoelectronics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.