Our research is motivated by the need to create new materials to solve existing problems relating to energy conversion and semiconductor devices.  We believe that revolutionary changes will likely stem from basic scientific and engineering studies of materials.  Our research efforts are therefore focused on the synthesis of new materials and interfaces and examination of the structural, electronic, and chemical properties therein.

Atomic Layer Deposition for Interfacial Control

Our group utilizes atomic layer deposition (ALD) to deposit thin oxide films on semiconductors.  The ALD process (pictured below) relies on self-limiting surface reactions from vapor phase precursors. This chemical deposition technique therefore allows for precise control of thicknesses and interfacial chemistry. Our team primarily investigates two aspects of ALD: Interfacial electronic properties and new chemistries/processing techniques.

Interfacial Electronic Properties

The chemical bonding and composition at semiconductor surfaces define the electronic properties of such interfaces, which are critical for a range of electronic devices including photovoltaics, photoelectrochemical devices, photodetectors, and field-effect transistors. Our group has generated new knowledge on the origin of fixed electronic charge at alumina-silicon interfaces using an in situ conductance measurement during ALD. We are exploring the extent to which interface structure and chemistry can be used to tune these electronic properties.

New Chemistries and Processing Techniques in Atomic and Molecular Layer Deposition

In some material systems, the crystal structures that can be created by ALD are limited.  For example, ALD alumina is almost always structurally amorphous after deposition.  We are examining post-deposition crystallization strategies that rely on crystalline seeds to initiate lateral crystallization of ALD thin films. Such techniques may allow access to structural forms and textures not previously accessible by ALD.

We gratefully acknowledge funding or contributions from the following:

• PITA, Pennsylvania Infrastructure Technology Alliance
• Intel
• DuPont
• Gelest, Inc.
• Solvay, Inc.
• National Science Foundation (CBET 1605129)
• Lehigh University