The chemistry and physics of indium phosphide semiconductor nanocrystals

A synthetic methodology has been devised for the production of size-selected, organically functionalized, highly crystalline Indium Phosphide semiconductor nanoparticles. A thorough characterization has been conducted including UV/visible absorption spectrophotometry, X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Infrared (IR) and Raman vibrational spectroscopies, Photoluminescence spectroscopy (PL), Nuclear Magnetic Resonance (NMR), and Elemental Analysis (EA). Quantum confinement effects are evident by the blue shift of the absorption and emission spectra as a function of size. The exciton dynamics of the system have been probed on short timescales using Resonance Raman spectroscopy and long timescales using PL. Resonance Raman spectroscopy has revealed a size dependence of the relative intensities of the longitudinal optical (LO) and the transverse optical (TO) modes. A theoretical model has been designed to predict Resonance Raman spectra in size-confined nanocrystals. Long timescale dynamics, probed using PL, show the importance of the extent of the surface trap energy. Maximum room temperature luminescence efficiencies for InP have been found to be around 0.05%. Creating quantum dot/quantum well (QDQW) structures by growing a shell of CdS on the surface of the InP has raised yields up to 5%. These systems hold great promise for device applications.