Colin Wolden

Weaver Distinguished Professor

BS - University of Minnesota
MS - MIT School of Chemical Engineering Practice
PhD - MIT

Research Description

Our research interests are directed at both synthesizing new electronic materials and developing novel processing techniques. Materials of interest include transparent conducting oxides (TCOs), wide bandgap semiconductors for photovoltaic applications, and advanced polymers. Primary deposition techniques for these thin film materials are thermal and plasma-enhanced chemical vapor deposition. Investigation of thermal CVD is guided by detailed reactive flow modeling and experimental measures of both gas-phase and surface kinetics. PECVD is a more complex phenomena, and we take a semi-empirical approach using statistically designed experiments. In both cases in-situ process diagnostics and ex-situ materials characterization are used to develop fundamental models that yield process-structure-performance relationships. Process diagnostics include mass spectrometry, optical emission spectroscopy (OES), and optical reflectometry/transmission. Routine characterization techniques include:

• Electrical Properties: C-V, I-V, 4 point probe, Hall effect, photovoltaic performance
• Optical Properties: Variable angle spectroscopic ellipsometry (VASE), UV-VIS-IR spectrophotometry
• Structural Properties: X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM)
• Film Composition: X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), secondary ion mass spectrometry (SIMS)

selected Publications

P. C. Rowlette, M. Canon, C. A. Wolden, "Digital control of SiO₂ film deposition at room temperature", J. Phys. Chem. C 113, 6906 (2009)

M. T. Seman, D. N. Richards, P. Rowlette, and C. A. Wolden, "An analysis of the deposition mechanisms involved during self-limiting growth of aluminum oxide by pulsed PECVD", Chem. Vap. Deposition 14, 296 (2008).

M. Seman, J. J. Robbins, S. Agarwal, and C. A. Wolden, "Self-limiting growth of tantalum oxide thin films by pulsed plasma-enhanced chemical vapor deposition", Appl. Phys. Lett. 90,131504 (2007).

S. Kosaraju, I. Repins and C. A. Wolden, "Formation of chalcogen containing plasmas and their use in the synthesis of photovoltaic absorbers", J. Vac. Sci. Technol. A 23, 1202 (2005).

J. M. Kestner, S. McElvain, S. Kelly, L. M. Woods, T. R. Ohno, and C. A. Wolden, "An experimental and modeling analysis of vapor transport deposition of cadmium telluride", Sol. Energy Mater. Sol. Cells 83, 55-65 (2004).

J. J. Robbins and C. A. Wolden, "High mobility oxides: engineered structures to overcome intrinsic performance limitations", Appl. Phys. Lett. 83, 3933-3935 (2003).