Atomic imprint crystallization and scanning near-field deposition for creating large area single crystal surfaces on amorphous substrates
Abstract
We pose the question: is it possible to create large area single crystal surfaces on arbitrary surfaces in scalable fashion? Our approach in tackling this problem is based upon pursuing two new materials approaches and their combination: (i) atomic imprint crystallization, and (ii) nearfield scanning nanoscale deposition techniques using localized chemical vapor deposition (CVD). Atomic imprint crystallization involves bringing a single crystal atomic surface in contact with an amorphous semiconductor surface, using the periodic potential on the single crystal surface to initiate solid phase epitaxial crystallization in the amorphous layer, and then debonding and retracting the crystalline surface non-destructively. Preliminary experiments have shown the promise of this method. Near field scanning deposition involves carrying out CVD based epitaxial growth at high spatial resolution (20-50 nm) using near field tips with embedded microfluidic capillaries through which the precursors are delivered close to the heated surface. Placing arrays of tips on a near field scanning stage will enable writing epitaxial features over large areas. Using tips with slotted linear openings will enable laterally growing out seeded crystalline surface layers in epitaxial registry. Both of these approaches aim at avoiding the key limiter to bulk solid phase epitaxial regrowth—the nucleation of heterogeneous rogue crystals in the near interface region. Using the approaches of (i) or (i)+(ii), we aim to develop new approaches for creating large area, thin (~3 nm to ~15 nm), single crystal surfaces and layers of semiconductors on arbitrary substrates. Our work will use the Si-Ge system as a test case. Adding z motion to the scanning tips, coupled with selective area deposition enables additive three dimensional growth of nanoscale architectures. All of this will require a detailed understanding of the energetic interaction between surfaces, interfacial chemistry, crystallization, debonding mechanics and lateral crystal growth processes. Our work will involve building the experimental equipment and tools for (i) and for (ii) and carrying out the detailed crystal growth, microstructural and electrical/optical characterization studies necessary. It will also involve understanding the epitaxy of thin single crystal surface layers where the epitaxial growth front is drawn laterally by scanning probe deposition with <50 nm lateral resolution. This is unlike most other treatments of epitaxy, which employ a broad beam source that impinges on the entire surface. Informing the experimental work will be molecular dynamics simulations of the imprint recrystallization process and the debonding/crack propagation kinetics. Central to this work will be the question: how can we control energetics across the interface so that it is strong enough for high quality solid phase epitaxy, yet weak enough for the interface to debond easily. If our project is successful, we will develop the science that will allow us to create large, scalable single crystal semiconductor surfaces on arbitrary substrates. It would offer unprecedented degrees of freedom to photovoltaic and microelectronics technologies by offering very high quality semiconductors (such as silicon) on substrates such as glass and metal and enabling hybrid three dimensional integration. This would result in high efficiency solar cells, and low power-high performance electronics. This would directly impact renewable power sources and wireless signal processing, sensing and logic processing for field applications. These are areas of direct relevance to DoD. From a scientific perspective, we would have developed and understood the underlying materials science for creating single crystal surfaces of semiconductors at will and on arbitrary substrates.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 19, 2018
- Source ID
- N000141812869
Entities
People
- Supratik Guha
Organizations
- Office of Naval Research
- United States Navy
- University of Chicago