Doping of Diamond and c-BN beyond Thermodynamic Solubility Limit for Solid State Devices
Abstract
This research program proposes a transformative approach to n- and p-doping of diamond and c-BN beyond the current state-of-the-art. The main concept is based on the recently discovered direct conversion of amorphous carbon into diamond and h-BN into c-BN at ambient temperatures and pressures in air in the form of large-area single-crystal films on substrates such as sapphire and silicon. The key advantage stems from the novel growth method, where the carbon layers are melted by using high-power nanosecond pulsed lasers in a highly super undercooled state, and then quenched rapidly either into a new state of carbon (Q-carbon) or into the single-crystal diamond phase in the presence of a template for diamond growth. Similarly, h-BN can be melted in a super undercooled state and converted into large-area single-crystal c-BN films. Accordingly, it is envisioned that dopant impurities present in the amorphous carbon and h-BN films can be incorporated into substitutional sites of diamond and c-BN during rapid liquid-phase crystallization via the phenomenon of solute trapping. As the proposed approach is a fundamentally nonequilibrium process, dopant concentrations in electrically active sites for both n- and p-types can far exceed the thermodynamic equilibrium solubility limits, while maintaining the energy levels, overcoming the long-standing challenge of diamond. Specifically, the feasibility studies on n-type doping (N, P, As and Sb dopants) will be carried out by incorporating these dopants into carbon by ion implantation, followed by rapid recrystallization from super undercooled state into epitaxial diamond thin film heterostructures. Similarly, n-type and p-type doping of c-BN will be achieved by Si and Zn dopants, respectively. The p-type (B dopants) doping of diamond will be accomplished by pulsed laser deposition of boron doped carbon layers at 500C in the presence of oxygen and hydrogen. Our preliminary results on nitrogen doping in diamond have already indicated that the dopant concentrations in electrically active substitutional sites can indeed be much beyond the thermodynamic solubility limits. Lattice location (substitutional versus interstitial) studies will be performed by using atomic resolution techniques and the results correlated with electrical activation and detailed carrier transport measurements. Theoretical calculations of dopant energy levels, ionization efficiencies, carrier concentrations and mobilities will be carried out in parallel to establish correlations with experimental results and to guide the fabrication of novel solid state devices. A primary goal of the combined effort is to demonstrate the p-n diodes of diamond and c-BN with satisfactory junction characteristics by controlling the dopant concentrations and the types vertically and/or laterally in the process. When successfully implemented, the proposed research is expected to revolutionize the doping and practical applications of diamond as well as the related materials such as c-BN.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 16, 2018
- Source ID
- W911NF1710596
Entities
People
- Jagdish Narayan
Organizations
- Army Contracting Command
- North Carolina State University
- United States Army