CASS Talks with Patricia Lustosa, PUC-Rio, Brazil

Abstract: In this talk two challenges shall be addressed, which quantum well infrared photodetectors (QWIPs), based on III-V semiconductors, face, namely: photodetection within the so-called “forbidden gap”, between 1.7 and 2.5 microns, and room temperature operation using thermal sources. First, to reach this forbidden wavelength range, a QWIP which consists of a superlattice structure with a central quantum well (QW) with a different thickness is presented. The different QW in the symmetric structure, which plays the role of a defect in the otherwise periodic structure, gives rise to localized states in the continuum. The proposed InGaAs/InAlAs superlattice QWIP detects radiation around 2.1 microns, beyond the materials bandoffset. Second, with the purpose of achieving room temperature operation, an asymmetric InGaAs/InAlAs superlattice, in which the QW with a different thickness is not in the center, is used to detect infrared radiation around 4 microns at 300 K. This structure operates in the photovoltaic mode because it gives rise to states in the continuum which are localized in one direction and extended in the other, leading to a preferential direction for current flow. Finally, the use of Artificial Intelligence methods to optimize the design of photodetector structures shall be addressed. Short Bio: Patrícia Lustoza de Souza received her B.A., M. Sc. and Doctor degrees in physics from the University of California, San Diego in 1981, from the San Diego State University in 1984 and from Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio) in 1989, respectively. In 1989 she joined PUC-Rio as an Assistant Professor, where she is now Full Professor and Head of the Semiconductor Laboratory. She is also head of the National Science and Technology Institute on Semiconductor Nanodevices – DISSE. She has been engaged in research in III-V semiconductor materials for electronic and optoelectronic devices. She is since 2006 an Olga Taussky Fellow from the Wolfgang Pauli Institute. Virtual: https://events.vtools.ieee.org/m/313584