Current Research Areas

* listed by alphabetic order. Please click the title for more information.

(1) Diffusion Barriers 

As the feature size in integrated circuits (IC) has decreased, the necessity for thermally stable, high conformity interface diffusion barriers has become more significant. Traditionally, aluminum and its alloys have been used for thin film interconnections. However, there was a recent transition from aluminum to copper as the interconnect material for IC due to copper’s higher resistance to electromigration and its lower resistivity. Unfortunately, copper has high mobility in Si and SiO2 and if migration of the metal can cause an increase in contact resistance, change in the barrier height, leaky pn junctions and destruction of electrical connections to the chip. As a result, a high quality diffusion barrier layer is essential to prevent Cu-Si interaction.

(2) Electrochemical Flow Visualization 

The quality of crystals grown from a melt is often deteriorated by the presence of buoyancy-induced convection resulting from temperature or concentration inhomogenities. For the past few years, our research group has been using Yttria-Stabilized Zirconia (YSZ) to develop a solid-state electrochemical cell to establish and measure dissolved oxygen boundary conditions defined by the Nernst equation. Simply, a packet of oxygen is electrochemically introduced into the liquid metal melt and is used as a tracer that is “seen” by the employed YSZ sensors.

(3) Gas-phase Chemistry of MOCVD precursors 

Chemical vapor deposition (CVD) is a widely used method to deposit thin films of a variety of materials, with most CVD processes developed and optimized by a lengthy and costly experimental approach.  Although detailed models can now reasonably describe transport in these relatively simple reactors, their usefulness is limited by the lack of knowledge of reaction mechanisms and values for the rate constants.  Our group has developed an up-flow, impinging-jet reactor that is interfaced to a Raman spectrometer.  Importantly, this test reactor can be translated x-y-z to allow temperature and composition profiles to be measured.  It is hypothesized that this system can be used to extract the kinetic data unambiguously. This hypothesis implies adequate sensitivity and response of the Raman system, and that in-situ probing of the gas phase reactions can be translated to information about the reaction mechanisms and kinetic data with the aid of detailed modeling. Recent increases in computing capacity and advances in computational fluid dynamics and computational chemistry now allow accurate interpretation of the Raman scattering data and extraction of rate constants and other physical properties. The goal of the research is to establish a reliable methodology to extract kinetic information of complex chemical systems relevant to CVD. 

(4) Group III - Nitrides 

AlN, GaN, InN, and the alloys of these materials have direct energy band gap which is essential for the application of optoelectronics.  These material systems cover whole visible and ultraviolet range. The application of group III - Nitride is LEDs (Red, Green, Blue, and UV), laser diodes, light detectors, solar cells as well as electronic devices. Group III-Nitride has been grown by QMOVPE (Quaternary Metalorganic Vapor Phase Epitaxy), and Merged H-MOVPE (hybrid MOCVD/hydride vapor phase epitaxy) system in our group.

(5) Photovoltaics

UF interdisciplinary photovoltaic research team which is consisted of four faculties (T.J. Anderson, O.D. Crisalle – Chemical Engineering, V. Craciun – Material Science & Engineering) has been working on the fundamental aspects of absorber and buffer layer materials, advanced process development, process modeling and control, and device characterization and simulation for thin-film Cu(In_1-x,Ga_x)Se₂ solar cells.