Collaborative Research: Composite Avalanche Nanoantenna Room-Temperature Infrared Photodetectors (CANTRIP)

Many of us have become familiar with infrared (IR) imaging during the COVID-19 pandemic as a method to rapidly screen for people with fevers. However, IR imaging is also useful for other medical diagnosis, astronomy, law enforcement, military vision systems, inspection of mechanical/electrical components, secure communications, energy/environmental assessments, and many more situations.

Despite these broad applications, IR imagers are expensive and generally require internal cooling systems. This work would develop a new class of thermal imager with the potential to be cheaper, more energy efficient, and operable with additional functionalities not presently available using existing technology. A breakthrough in this area will enable thermal imaging to become part of everyday life.

In this work, the investigators will create hybrid detectors that integrate nanoscale antennas with photodetectors, which should enable increased functionality while also reducing system cost and complexity compared to the present state of the art systems. Both investigators have a long history of outreach of integrating their research with the broader community; and through this work, they plan to initiate new outreach efforts about the interaction of light, materials, and structures to show students of a variety of ages and backgrounds the excitement of “viewing the invisible.”

This research aims to develop a fundamentally new mechanism for room temperature, long wavelength infrared (LWIR) photodetection using a combination of nanoantenna arrays and avalanche diode technologies. We will advance the state of photodetection by combining: a) active photonic design, b) antenna array theory, and c) customized semiconductor materials/devices.

With later development (e.g. microlens arrays for achieve high fill factors) these photodetectors could become the new dominant paradigm replacing the existing, costly imagers. Our solution combines photodetection technologies and anisotropic nanoantenna designs to create a first-in-class, hybrid photodetection system. This novel combination relies on the theoretical foundation of active frequency selective systems and those of highly sensitive avalanche photodiodes.

To achieve this foundation, the challenges associated with a hybrid semiconductor/metallic nanoantenna modeling must be investigated as, with only a few exceptions, the need to integrate optical responses with semiconductor carrier mobility has been a largely overlooked area. Although, many of the associated interactions have been successfully modeled independently, there have been significant hurdles in producing full-wave simulation which integrate electromagnetic excitations with semiconductor carrier mobilities and charge distributions.

Our models will incorporate localized carrier injection and transport modeling to develop an avalanche diode growth profile including semiconductor choice, bandgap, doping profile, and layer thickness. The interplay of these parameters is fundamentally different than traditional photodiode material systems will be analyzed to understand the nanostructure/semiconductor interactions at a fundamental.

Since the choice of material system is an important one for this project to succeed, the project will consider GaAs based avalanche diodes, as well as InP and/or GaP due to the versatility of the III-V heterojunction materials system enabling adaptability as new challenges arise. The molecular beam epitaxy systems employed in this work are capable of intermixing any of the common III-V elements (Al, Ga, In, Tl and P, As, Sb, Bi) to achieve a wide range of potential material properties.

As such, parameters such as the localized carrier injection can be adjusted using semiconductor growth profiles and doping concentrations to achieve the desired induced photocurrent. Through the thorough analysis of modeling, anisotropic antenna design, and unique semiconductor growth profiles, this work provides a novel path to understanding a revolutionary electromagnetic imaging architecture.

Specifically, we are using an IR signal to excite an anisotropic nanoantenna which will stimulate the avalanche process in an integrated semiconductor junction. The resulting room-temperature photodetectors will minimize thermal noise, increase functionality, and be a first-in-class-innovation.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.