Wednesday, March 31, 2004
306 Soda Hall, Hewlett-Packard Auditorium
4:00-5:00 p.m.

Professor Dennis Deppe

Electrical and Computer Engineering Dept.,
University of Texas at Austin

Epitaxial Nanostructures for Nanophotonics and Novel Optoelectronic Devices

Abstract:

Self-organized nanostructures grown using molecular beam epitaxy provide a route to fabricate very high quality quantum dots (QDs) in III-V device structures. The QDs confine electrons and holes to dimensions of their de Broglie wavelengths, and therefore create zero-dimensional electronic states. QDs enable new types of optoelectronics devices such as QD lasers, optical amplifiers, detectors, and nanophotonic devices. Their novel electronic structure can enhance present device performance as well as create new types of devices. The QDs enable scaling of III-V devices to their minimum dimensions set by the respective wavelengths of photons and charge carriers. They are particularly important for new technologies based on vertical-cavity surface-emitting lasers, microdisks, and photonic crystal devices.

In this talk we will present research being conducted into the growth of III-V nanostructures and their application to QD lasers and light emitters. The nanophotonic devices can give rise to a significant Purcell effect that modifies an emitter’s spontaneous emission rate and enables high speed, low power lasers. Because of their electronic confinement, QDs also provide the ideal active region for dense photonic integration, directly modulated lasers with low chirp, and high speed modulation. In this talk we will also discuss the latest understanding of energy relaxation in III-V nanostructures, the cause and the elimination of bottlenecks in the relaxation, and novel physics associated with quantum dimensionality and electronic coupling of 0-D states to more commonly employed 2-D structures for both photons and electrons. We also discuss how QDs can impact ultrafast laser sources, and enable new types of terahertz sources.

Dennis G. Deppe received the B.S., M.S., and Ph.D. degrees in electrical engineering from the University of Illinois at Urbana-Champaign. His Ph.D. work centered on atom diffusion in III-V semiconductor heterostructures and its use in superlattice disordering. After obtaining his Ph.D. he was employed as a Member of Technical Staff at AT&T Bell Laboratories in Murray Hill, New Jersey, where he researched and developed vertical-cavity surface-emitting lasers. In 1990 he joined the University of Texas at Austin where he is a Professor in the Electrical and Computer Engineering Department. His research specialties include optoelectronics, laser physics, epitaxial crystal growth, and quantum optics. His group at UT has developed a number of “firsts” in the area of semiconductor light sources, including the first microcavity LEDs, the first oxide-confined VCSELs, and the first 1.3 µm QD lasers. Prof. Deppe has won several awards for his research into optoelectronic devices, most recently the OSA Nicholas Holonyak Award, the IEEE Distinguished Lecturer Award, and the IEEE LEOS Engineering Achievement Award. He is a Fellow of the OSA and the IEEE.