Palestra do PPGF com o Prof. Dr. Fabian Hartmann

Título da palestra: Mid-Infrared Photodetectors based on Resonant Tunneling Diodes and Interband Cascade Structures Palestrante: Fabian Hartmann/ Technische Physik, Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany. A palestra acontece na quarta-feira 27 de novembro ás 16h30 na Sala de Seminários Jorge André Swieca (nova), no departamento de física.

Resumo: The increasing demand for mid-infrared (MIR) light sources suitable for, e.g. molecule or gas sensing applications, has driven the development and optimization of novel MIR laser concepts such as quantum cascade lasers (QCL) or interband cascade lasers (ICL) within the recent years. Despite the excellent progress on MIR light sources, there is still a lack in appropriate MIR photodetectors. Here, we present and discuss two promising and novel GaSb/InAs-based detector concepts covering the wavelength range between 3-6 µm, i.e. the MIR wavelength range that includes the "fingerprints" of many chemical compounds of gases. First, resonant tunneling diode (RTD) photodetectors as an alternative to avalanche photodetectors. In RTDs, amplification of photogenerated minority charge carriers is based on modulation of a majority charge carrier resonant tunneling current. We present RTD based photodetectors consisting of a GaAsSb/AlAsSb double barrier structure and a quaternary Ga0.64In0.36As0.33Sb0.67 absorption layer, which are sensitive to light illumination up to a wavelength of 3.5 μm. Second, we discuss interband cascade photodetectors (ICD), in which a cascading scheme allows for fast carrier extraction and a compensation of the diffusion length limitation. ICDs combine the advantages of optical interband transitions of type II superlattice photodetectors with the excellent transport properties and the cascading principle of ICL structures.