CEMS Faculty

Our research focuses on solving technologically important fundamental problems encountered in electronic materials processing. Specifically, we are interested in understanding thin film deposition and etching processes used in manufacturing of microelectronic systems and photovoltaic devices. Currently, our research program is focused on four specific research areas. These are

(1) synthesis of ZnO nanowires and their applications in photovoltaics,
(2) metalorganic chemical vapor deposition (MOCVD) of ZnO films,
(3) plasma etching of deep trenches and holes in Si, and
(4) plasma deposition of nanocrystalline silicon films.

ZnO Nanowires for Photovoltaics - Our objective is to synthesize ZnO nanowires and nanostructures and assemble them into mesoscopic ordered or disordered structures to exploit their electronic and optical properties. Such structures can have potential applications as solar cells, luminescent devices and chemical detectors. Specifically, we focus on applications of ZnO nanostructures in dye sensitized solar cells and study the relation between synthesis conditions, materials properties and solar cell characteristics. The goal is to design and develop efficient, low cost solar cells to harness solar energy.

MOCVD of ZnO Thin Films - ZnO is a wide band gap semiconductor and can be used to make ultraviolet diodes and lasers. Despite its enormous potential, very little is known about the growth and electronic properties of ZnO. We grow ZnO films through MOCVD from zinc acetlylacetonate. The morphology and properties of the films depend on the deposition conditions. We use in situ surface sensitive spectroscopic techniques in conjunction with ex situ film characterization to understand the process-structure-property relations in ZnO MOCVD.

Plasma Etching - Plasma etching of high aspect ratio (depth:width) structures enable the fabrication of a wide variety of devices including nozzles for inkjet printing and capacitors for memory cells. We study the homogeneous and heterogeneous reactions and transport phenomena occurring in chemically reactive gas plasmas. The objective is to understand how process conditions dictate plasma properties which in turn affect the etch rate, selectivity with respect to the mask, uniformity and anisotropy. We use multiple surface and plasma characterization methods to investigate the key factors that determine the ability to etch high aspect ratio features into silicon. We complement the experiments with modeling of the plasma and the feature profile evolution.

Plasma Deposition - Thin films containing nanometer size Si grains have tremendous potential for various applications in single electron transistors and memory devices and solar cells. Such films can be deposited by plasma enhanced chemical vapor deposition from silane. Our research in this area is aimed at obtaining fundamental information on plasma-surface interactions that occur during PECVD. We are addressing the questions of how radicals and molecular fragments from chemically reactive plasma interact with surfaces of substrate materials or already deposited films and how these interactions determine the structure and composition of the deposited films.