Nitride thin film growth by ENABLE-MBE
Todd L. Williamson, Los Alamos National Laboratory
Monday, Feb. 10, 2014 at 2 p.m.
Engineering Research Center (ERC) 490 [map]
Across a diverse range of many technologies and applications, thin film synthesis plays an important role in determining the overall functionality of devices. In particular, nitride thin films have become key electronic materials in many emerging technologies, including solid state lighting, laser diodes, and power electronics. Our team at LANL has developed an advanced molecular beam epitaxy (MBE) thin film growth technique that has been used for growth of a broad range of nitride thin films materials called energetic neutral atom beam lithography & epitaxy (ENABLE). ENABLE utilizes a high flux energetic beam of neutral N atoms (kinetic energies of 1 to 5 eV) for nitride thin film growth, which alters the energetics for film growth by providing a direct energy source for overcoming reaction barriers. This energy activation reduces the role of high substrate temperatures as the primary means to overcome reaction barriers. Nitride film growth occurs when the energetic N atoms react on a substrate with an evaporated flux of B, Al, Ga, In, Nb or other materials in a clean UHV MBE environment. One of the main advantages of ENABLE over other MBE techniques is that the high flux afforded by the ENABLE atom source allows for significantly faster growth rates. Growth rates of >5 microns/hr have been demonstrated for group III nitrides. This talk will provide an overview of the ENABLE technology and then highlight growth efforts in three distinct areas, the AlGaInN alloy system for optoelectronic applications, NbN for superconducting nanowire single photon detectors, and boron containing nitrides for neutron detection.
Todd Williamson is a staff scientist at Los Alamos National Laboratory (LANL) in Los Alamos, NM. He received his B.S. in Chemistry from the University of Texas-Austin in 1999, and his Ph.D. in Chemistry from the University of Illinois-Urbana/Champaign in 2005 studying the production, characterization, and applications of porous semiconductors. He was a Harold M. Agnew postdoctoral research fellow at LANL from 2005 to 2009 where he demonstrated the use of ENABLE-MBE to grow high quality GaN and In-rich InGaN for optoelectronic applications. His current research interest is in the application of ENABLE-MBE to a broad range of nitride thin film syntheses.