Backside illuminated infrared detectors with plasmonic resonators

Abstract

Next generation infrared photodetector technology will require focal plane array (FPA) systems that have multi-spectral imaging capabilities. One proposed approach to realizing these multicolor devices is to use plasmonic resonators. However, device development and characterization are commonly addressed with large front side illuminated single pixel detectors on a supporting epitaxial substrate. The focal plane arrays on the other hand are backside illuminated. Moreover, in a front side illuminated device, there is significant substrate scattering of the incident light. Here, we propose a method for the accurate measurement of device performance by using a hybridized chip design (hybrid chip) that is similar to the fabrication of an FPA system, with the substrate completely removed through a combination of mechanical polishing and subsequent wet etching techniques. The hybrid chip was also designed to precisely characterize the effects of varying mesa size by incorporating square mesa structures that range from 25 to 200 μm in width. This approach offers an advantage over conventional device characterization because it incorporates mesas that are on the same scale as those normally used in FPA systems, which should therefore provide a fast transition of new photodetector technology into camera based systems. The photodetector technology chosen for this work is a multi-stack quantum dots-in-a-well (DWELL) structure designed to absorb electromagnetic radiation in the mid-infrared spectral range.