03-04-2017 14:30  Electro-optics and Microelectronics Seminar

III-Nitrides Based Intersubband Quantum Cascade Detectors enhanced performance by Nano-Structures

In recent years the Quantum Cascade Detector (QCD) has emerged as an alternative for the quantum well infrared photodetector (QWIP). The fundamental building-block of a QCD consists of an active quantum well (QW) where electron excitation occurs upon photon intersubband (ISB) absorption, and multi-quantum well extractor that transfers the excited electron to the ground level of the following active QW. A major drawback of the QCD in applications based on normal light incidence is related to the polarization selection rule of QW inter-subband transitions (ISBT), allowing absorption only for an electric field polarized perpendicular to the QW layers (Ez). In this work we propose two new different normal incident light coupling antennas solutions. First, the use of a two-dimensional metallic hole array (MHA) allows the coupling of surface plasmons waves (SPW) to the absorption region of the QCD. The generated SPW mode exhibits a dominant electric field component normal to the surface that is the proper polarization for exciting the ISB resonance. The second light coupling scheme involves planar "H" nano antenna arrays. Incoming normal incidence light is transferred into the z component of the electric field and is strongly localized underneath the antenna. Consequently, the Ez field can strongly interact with the ISBT of the detector. We present the design, realization and full characterization of the antennas-integrated normal incidence infrared QCD. Specifically, we demonstrate the detection for a signal enhancement of up to a factor of 9 compared to the standard wedge characterization. In addition, interesting results related to strong light matter coupling between ISBT and nano-antenna will be shown.

Location: 1061
Speaker: Matias Katz
Affiliation: Dept. of Electrical Engineering Technion Back