Remi Beaulac of Michigan State University is supported by an award from the Macromolecular, Supramolecular and Nanochemistry Program of the Division of Chemistry to investigate the chemistry and physical properties of nitride nanomaterials. These materials are expected to play a significant role in the design of new light-emitting devices, biomedical imaging methods, information and telecommunication applications, as well as in future solar-based energy storage and conversion schemes. At the moment, simple and reliable methods to prepare high-quality nitride nanomaterials by direct solution-based chemical approaches are unknown, and their electronic, optical, magnetic, and chemical reactivity properties are consequently ill-understood. The work conducted under this award is expected to change this situation by virtue of a new chemical scheme that allowed the group to prepare uniquely high-quality indium nitride (InN) nanomaterials. Both indium nitride and gallium nitride (GaN) are archetypical members of the so-called III-V semiconductors family that have long been difficult to prepare chemically. Therefore chemical synthesis of nanocrystals of both materials is being pursued.
Professor Beaulac's efforts are divided into three main categories: (1) Design of rational schemes for the synthesis of nitride colloidal nanomaterials; (2) Reversible control of n-type doping in these materials; (3) Investigation and tuning of the physical properties of nitride nanomaterials. Under the first heading, the mechanisms behind the efficacy of the approach uncovered for InN are studied, extending the approach to produce more complex structures such as ternary alloys and heterostructures, anisotropically-grown nanostuctures (platelets, rods, and wires). Particular attention is given to unravelling the complexities of the synthetic approaches devised by studying the energetics and kinetics of the nucleation and growth processes in nitride materials chemistry, which is a key step toward the optimization of these synthetic approaches to reproducibly obtain high-quality colloidal nitride nanomaterials that exhibit high homogeneity in size and shape. In a parallel step, the Beaulac group is undertaking a broad and detailed analysis of the potential of nitride nanomaterials to reversibly act as heavily-n-type doped materials. Indium nitride is postulated to be a very potent oxidant in view of its very low-lying conduction band, which is most certainly the basis for the difficulty in preparing the material in the undoped form. Finally, in-depth characterizations of the physical properties associated with this new class of materials are also conducted with regards to three potential fields of impact, namely photodetector devices, photovoltaics applications, and spintronics technologies.
