Physics (Internal)

Band structure engineering for novel infrared semiconductor lasers

This event is part of the Biophysics/Condensed Matter Seminar Series.

Abstract
Quantum confinement in the conduction band of semiconductor heterostructures leads to interesting optical material properties in the infrared range of the electromagnetic spectrum. Research on intersubband transitions in recent years has resulted in numerous fundamental discoveries and technological applications. The quantum cascade laser (QCL) is possibly the most successful device application of intersubband transitions. As a compact, high-power light source, the QCL is ideally suited for practical applications such as trace-gas sensing for environmental and defense applications, and free-space telecommunications. I will describe our ongoing efforts to advance the understanding of intersubband transitions and charge transport as they relate to QCL operation. Our approach is interdisciplinary in nature involving elaborate band-structure modeling, material growth, and characterization, as well as device design and testing. In particular I will focus on current research to explore new materials and light generation mechanisms. To achieve surface emission from QCLs, we are studying intra-valence band transitions in GaAs/AlAs heterostructures. Finally, I will discuss the fascinating opportunities promised by nano-structured nitride materials for near- and far-infrared light emission.