Ultra-thin plasmonic detectors

Plasmonic materials, and their ability to enable strong concentration of optical fields, have offered a tantalizing foun- dation for the demonstration of sub-diffraction-limit photonic devices. However, practical and scalable plasmonic optoelectronics for real world applications remain elusive. In this work, we present an infrared photodetector leverag- ing a device architecture consisting of a “designer” epitaxial plasmonic metal integrated with a quantum-engineered detector structure, all in a mature III-V semiconductor material system. Incident light is coupled into surface plasmon- polariton modes at the detector/designer metal interface, and the strong confinement of these modes allows for a sub-diffractive (∼λ0/33) detector absorber layer thickness, effectively decoupling the detector’s absorption efficiency and dark current. We demonstrate high-performance detectors operating at non-cryogenic temperatures (T= 195 K), without sacrificing external quantum efficiency, and superior to well-established and commercially available detectors. This work provides a practical and scalable plasmonic optoelectronic device architecture with real world mid-infrared applications.Lockheed Martin; National Science Foundation (NNCI- 1542159); Defense Advanced Research Projects Agency (NASCENT, NLM program); Division of Materials Research (1720595); Division of Electrical, Communications and Cyber Systems (1926187).Center for Dynamics and Control of Material

All-epitaxial guided-mode resonance mid-wave infrared detectors

We demonstrate all-epitaxial guided-mode resonance mid-wave infrared (MWIR) type-II superlattice nBn photodetectors. Our detectors consist of a high-index absorber/waveguide layer grown above a heavily doped (n þþ), and thus, low-index, semiconductor layer, and below a high-index and wide-bandgap grating-patterned layer. Polarization- and angle-dependent detector response is measured experimentally and simulated numerically, showing strongly enhanced absorption, compared to unpatterned detectors, at wavelengths associated with coupling to guided-mode resonances in our fabricated detectors. The detectors show high operating temperature (T ¼ 200 K) external quantum effi- ciencies over 50% for TE-polarized light with absorber thickness of only 250 nm ( ko=20). We calculate T ¼ 200 K estimated specific detec- tivity for our detectors, on resonance, of 4 10 10 cm Hz1=2 W 1, comparable with state-of-the-art MWIR detectors. The presented results offer an approach to monolithic, all-epitaxial integration of IR detector architectures with resonant optical cavities for enhanced detector response across the mid-wave infrared.This material was based upon work supported by the United States Army under Prime Contract No. W909MY-20-P-0010. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the U.S. Army. The authors gratefully acknowledge support from the National Science Foundation (No. ECCS-1926187 and MRSEC Program No. DMR-1720595). Part of the work was done at the University of Texas Microelectronics Research Center (The Texas Nanofabrication Facility), a member of the National Nanotechnology Coordinated Infrastructure (NNCI), supported by the National Science Foundation (No. ECCS- 2025227).Center for Dynamics and Control of Material

Guided-mode resonance enhanced mid-infrared photodetectors

To leverage appealing applications in mid-infrared wavelength, photodetectors with high-performance, both optically and electrically, are desired. Majority of this thesis discusses guided-mode resonance enhanced mid-wave infrared (MWIR, 3 − 5 μm photodetectors. Chapter 1 gives a brief overview on type-II superlattice infrared photodetectors (T2SL), guided-mode resonance (GMR) and highly-doped semiconductors (n⁺⁺). We then discuss leveraging n⁺⁺ for GMR enhancement in T2SLs in an all-epitaxial design. In Chapter 2, we demonstrate a GMR enhanced MWIR detector at T = 79 K. In chapter 3, we further optimize our GMR photodetector design and demonstrate a high-operating temperature (HOT) GMR photodetector with over an order enhancement in external-quantum efficiencies (EQE) and over 4 × 10¹⁰ cm√Hz/ specific detectivity, D* in an ultra-thin absorber only 250 nm thick. Chapter 4, we investigate and optimize GMR photodetectors further to achieve room-temperature operation (RT) at low operating biases with about an order enhancement in EQE with D* > 1 × 10¹⁰ cm√Hz/, a superior value compared to state-of-art III-V photodetectors. In chapter 5, to show potential integration in focal-plane arrays, we integrate RT GMR photodetectors in flipchip configuration and demonstrate enhanced response in backside illuminated GMR photodetectors at room-temperatures. Apart from our research in GMR MWIR photodetectors, this thesis also discusses long-wave infrared (LWIR,8 − 13 μm) topological phonon chain in Chapter 6. In this chapter, we model bi-periodic chain of AlN pillars with subwavelength diameter and show through surface phonon coupling, the AlN chain can support edge-mode (an important parameter in topological insulators). We further study fabricated and grown chains of AlN pillars through reflection measurements. Finally, we summarize the thesis with a conclusion in chapter 7.Electrical and Computer Engineerin