Title

Amorphous ln-Sn-Zn-0

Presenter Information

Mathew Pollard

Department

Physics

Major

Physics

Research Advisor

Medvedeva, Julia E.

Advisor's Department

Physics

Funding Source

NSF-CEMRI Proposal

Abstract

Amorphous oxide semiconductors (AOSs) exhibit a rare combination of high optical transparency and high electron mobility surpassing that of amorphous silicon by orders of magnitude. Owing to the high electronegativity of oxygen anions and, hence, their strong interaction with metal cations, the network of metal-oxygen polyhedra is preserved on going from the crystalline to the amorphous state. Yet, variations in the oxygen coordination and distortions in the cation-anion chains alter the structure of valence and higher-energy conduction bands making it possible to tune the AOS properties. We employ first-principles density-functional calculations to investigate the structural and electronic properties of amorphous Zn-Sn-ln-0 and to determine how tensile strain affects the metal-oxygen bond lengths, bond angles, and coordination numbers in the oxide. Next, we identify the defect states responsible for the conductivity by calculating the atomic contributions to the valence and conduction band wave functions and characterize the defects structurally.

Biography

Mathew was born September 14, 1993 and raised in St. Louis County near Fenton. He graduated from Rockwood Summit high school. Received Eagle Scout in the Boy Scouts of America and was admitted to Missouri University of science and Technology in 2012. Mathew is majoring in physics and started research for Dr. Medvedeva.

Research Category

Sciences

Presentation Type

Oral Presentation

Document Type

Presentation

Location

Upper Atrium/Hallway

Presentation Date

03 Apr 2013, 9:00 am - 11:45 am

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Apr 3rd, 9:00 AM Apr 3rd, 11:45 AM

Amorphous ln-Sn-Zn-0

Upper Atrium/Hallway

Amorphous oxide semiconductors (AOSs) exhibit a rare combination of high optical transparency and high electron mobility surpassing that of amorphous silicon by orders of magnitude. Owing to the high electronegativity of oxygen anions and, hence, their strong interaction with metal cations, the network of metal-oxygen polyhedra is preserved on going from the crystalline to the amorphous state. Yet, variations in the oxygen coordination and distortions in the cation-anion chains alter the structure of valence and higher-energy conduction bands making it possible to tune the AOS properties. We employ first-principles density-functional calculations to investigate the structural and electronic properties of amorphous Zn-Sn-ln-0 and to determine how tensile strain affects the metal-oxygen bond lengths, bond angles, and coordination numbers in the oxide. Next, we identify the defect states responsible for the conductivity by calculating the atomic contributions to the valence and conduction band wave functions and characterize the defects structurally.