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Event 

Title:
Anderson Janotti: Localization in metal oxide semiconductors
When:
31.05.2012 11.00 h
Where:
Matéria Condensada Teórica - Niterói
Category:
Seminários

Description

Localization and delocalization of charge carriers in transition-metal oxide semiconductors

Anderson Janotti (UCSB - EUA)


There is great interest in developing transition-metal oxides such as TiO2 or SrTiO3 for semiconductor devices applications.   As with any semiconductor in the early stages of development, one of the main challenges is to control the conductivity by doping and reducing the concentration of native defects and unintentional impurities, thus, minimizing their deleterious effects.  These transition-metal oxides significantly differ from conventional semiconductors (III-V, Si, and Ge) with respect to their electronic structure and electronic transport.  While in conventional semiconductors, electron and holes originated from doping are delocalized and result in high carrier mobility, excess electrons in TiO2 and SrTiO3 occupy degenerate conduction bands derived from Ti d states, leading to a variety of interesting physical phenomena; for instance, is often argued that transport in TiO2 occurs through hopping of small polarons (electronic defects), giving rise to relatively low electron mobility. Here we will present results of density functional theory and hybrid functional for electronic and structural defects in TiO2 and SrTiO3.  We will discuss the effects of charge localization on specific sites in TiO2 and the consequences for optical and transport measurements. Shortcomings of the conventional density functional methods in describing charge localization will also be addressed.

A palestra será proferida em português

Venue

Group:
Matéria Condensada Teórica
Street:
IF-UFF
ZIP:
24210-346
City:
Niterói
State:
RJ
Country:
Country: br

Description

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