Many applications in photonic and electronic devices require high quality semiconductor crystal growth on supporting materials that do not intrinsically promote, nor are compatible with current manufacturing processes. The essential, but still challenging step is the deliberate templating of nanocrystals with the desired size, orientation and placement accuracy on such substrates. This award supports fundamental research to acquire knowledge for achieving nanoscale control of nucleation and crystal growth processes. The research will open the way to the fabrication of thin crystalline domains on inexpensive and abundant substrates as well to the fabrication of quantum nanodevices. Applications include thin film transistors for advanced displays, high performance thin film solar cells, three-dimensional electronic devices and quantum computers. The research will benefit the U.S. industry, economy and society. The coupled experimental and computational methodology and state of the art nanofabrication will provide new opportunities for undergraduate and graduate students and in particular underrepresented minorities to have research experiences and state-of-the-art training in nanoscience and engineering, consequently positively impacting engineering education.
Nanocrystal seeds with highly uniform size and orientations will be manufactured by laser crystallization in confined nanodomains. The research team will achieve fundamental understanding of laser crystallization in nanodomains by combining direct imaging via in situ Transmission Electron Microscopy (TEM) with detailed multi-scale computational modeling and molecular dynamics (MD) simulations. This uniquely integrated research approach will enable engineering of the nanoconfinement geometry and the imposed transient laser protocol parameters for reliable generation of well-controlled seeding nanocrystals. State of the art focused ion beam (FIB) processing and laser interference lithography will be utilized to define nanocavities with minimum diameter <10 nm wherein amorphous semiconductors (Si, Ge) will be deposited. Nano-cavities on large area will be fabricated by nanoimprinting with FIB fabricated molds. Pulsed laser radiation in combination with modulated background heating will be utilized to convert the amorphous deposits into nanocrystals with deliberately engineered size and crystallographic orientation. Such generated localized crystals can serve as crystallization seeds, overcoming uncertainty associated to un-engineered spontaneous nucleation. Molecular Dynamics (MD) simulation will be performed at the same length scale to provide fundamental understanding of heat transfer, nucleation mechanism, crystal growth and defect evolution in nano-confined domains. Finally, a seeded crystallization process will enable controlled growth of a large area monocrystalline thin layer on epitaxially non-participating substrates.
