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Thursday, August 14 • 11:00 - 13:00
Narrow-Gap Semiconductor II

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11:00-11:15

Oral: Mario Capizzi
Effects of Hydrogen Irradiation on the Electronic Activity of Nitrogen & Surface Defects in In(AsN) Alloys for the Mid-Infrared
Co-authors: Antonio Polimeni, Manoj Kesaria, Qiandong Zhuang, Anthony Krier, Francesco Mura, Giorgio Pettinari, Anton Velichko, Amalia Patanè 

11:15-11:30
Oral: Javad Shabani
Fabrication & Characterization of Gate-Defined Structures in Epitaxially Grown InAs Heterostructures
Co-authors: Tony McFadden, Borzoyeh Shojaei, Christopher Palmstrom

11:30-12:00
Invited: Michael Möller
Surface Effects on Optical Properties of InAs/InP Core/Shell Nanowires
Co-authors: Douglas S. Oliveira, Alejandro Molina-Sánchez, Mauricio M. de Lima Jr., Andrés Cantarero, Everton Geiger Gadret, Mônica A. Cotta, Fernando Iikawa, Paulo Motisuke 

Semiconductor nanowires (NWs) are very promising for optoelectronic device applications. Due to their large surface to volume ratio, surface conditions strongly affect the emission properties. In particular, for small band gap materials an electron accumulation layer can be formed at the surface, pinning the Fermi level above the conduction band minimum. In order to reduce the surface effects and enhance optical emission, various passivation methods have been investigated. However, a clear understanding of the surface effects is still missing. Here, we studied the influence of the surface on the optical properties of wurtzite (WZ) InAs and core/shell InAs/InP NWs.

We observed remarkable time-evolution of the photoluminescence spectra of all samples in few weeks. Soon after growth, samples present a strong optical emission band around 2.5-2.6 m. After some weeks, a drastic decrease of its intensity is observed while an additional band appears at ~3 m. The former band is attributed to the WZ band gap transition up to the Fermi energy. The latter, to stacking faults that form type-II multi-quantum wells along the NW, or to impurity recombination. This unusual result can be explained based on the Fermi energy variation with time due to the modification of the surface electron density caused by the adsorption of atoms and molecules at the NW surface. Although the nature of the adsorbates is still unknown, a self-consistent calculation of the carrier density and Fermi level position in the NW corroborate the results.

12:00-12:15
Oral: Anton Velichko
Hot Electron Induced Impact Ionization & Large Room Temperature Magnetoresistance in High-Mobility InAs
Co-authors: Amalia Patane, Oleg Makarovskiy, Nobuya Mori, Anthony Krier, Qiandong Zhuang

12:15-12:30
Oral: Vincent R. Whiteside
Hot-Carrier Effects in Narrow-Gap InAs & GaSb Materials: Potential for Next Generation Photovoltaics
Co-authors: Jinfeng Tang, Hamidreza Esmaielpour, Sangeetha Vijeyaragunathan, Tetsuya Mishima, Michael B. Santos, Ian R. Sellers

12:30-12:45
Oral: Giorgio Pettinari
Hydrogen-Induced Band-Gap Opening in InN
Co-authors: Antonio Polimeni, Mario Capizzi, Amalia Patanè, Vadim Lebedev 

12:45-13:00
Open 

Session Chairs
CP

Christopher Palmstrom

Professor, Department of Electrical & Computer Engineering, UC Santa Barbara
Professor Chris Palmstrom, one of the world's leading researchers of electronic materials, joined the ECE faculty at UCSB in the Fall of '07. Born in Norway, Palmstrom received his PhD in Electrical and Electronic Engineering from the University of Leeds (England) in 1979. After five years of research on semiconductor materials and contact techonologies at Cornell, he joined Bellcore in 1985. There, he did groundbreaking research on semiconductor... Read More →

Speakers
MM

Michael Möller

Instituto de Física Gleb Wataghin, UNICAMP


Thursday August 14, 2014 11:00 - 13:00
Room 16B

Attendees (4)