Erik Jonsson School of Engineering & Computer Science Materials Science and Engineering UT Dallas
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Research

In our laboratory, we use molecular beam epitaxy (MBE) to enable the growth of extremely precise, low defect materials with unique properties.  An integrated, three-chamber MBE deposition system has been established and linked together with a UHV backbone transfer system. In the Group IV chamber, we grow Si and Ge epitaxial films, SiGe compounds, and strained heterostructures.  The III-V chamber has recently been upgraded with new hardware and includes the capability of growing any combination of high-quality In, Ga, As, P, Al, and N compounds as well as in-situ H-cleaning and C, Be, and Si doping. The II-VI chamber can produce a number of films including CdTe, ZnS, and Be and Se compounds.  Each chamber is fully controlled by computer and operates at a base pressure in the 10-11 mbar range.  In-situ analytical tools allow us to assess growth quality in real-time and are coupled with the university's extensive ex-situ characterization facilities.  These MBE capabilities allow us to study materials that are important for a number of applications such as:

  • Photovoltaics: We are studying the nucleation and growth of very low defect multi-junction solar cells. These junctions are grown using MBE to make numerous III-V (GaAs, InGaP, etc) semiconductor materials with various lattice structures and energy band gaps in an effort to improve the efficiency of these types of solar cells. Using growth techniques, such as metamorphic buffer layers, our goal is to improve the efficiency of PV to a level that would allow widespread terrestrial use.  We also study other unique solar cell structures (and LEDs) using quantum dots which allow for the absorption of photons from a broader energy range.  Thin film II-VI materials such as CdTe are also being investigated.

 

  • Li-ion Batteries: We are investigating numerous aspects of Li-ion batteries for enhanced energy storage. This includes solid electrolytes (LLTO), advanced cathode materials (LiNiMnO2), next-generation anode materials (Si nanotubes), and the associated solid-electrolyte interphase (SEI).  Using chemical synthesis methods and epitaxial growth techniques, novel structures are formed that allow us to control the Li+ reaction pathways in these materials.  The insight gained of the chemical bonding and transport in these materials and interfaces are directly applied to full-cell batteries fabricated in our lab for correlation to charge storage capabilities.

 

  • III-V Nanoelectronics: Using our growth capabilities, we are developing and investigating a wide range of III-V (as well as Ge and Si) semiconductor materials and heterostructures for use in low-power CMOS technologies.  Collaborating with many of the other research groups in MSEN and building on the department’s reputation in this field, we are developing a detailed understanding of these III-V systems to enable electronics to maintain high-performance yet consume less energy.

 

 

We have established collaborations with other researchers in Materials Science, Physics, Electrical Engineering, and Chemistry.  We work closely with researchers at NIST and from other universities (for example NC State, Purdue, Dublin City University, and University College Cork), and we maintain ongoing projects and collaborations with U.S. Industries (Texas Instruments, SRC, SEMATECH).  Our goal is to develop a fundamental understanding of the issues associated with energy harvesting, reduction, and storage to significantly advance the scientific community, while greatly contributing to technological advances and environmental responsibility.