Moving towards detection of nanoantenna excitation using bandgap agnostic impact ionization

As photodetection moves towards longer wavelengths, the semiconductor bandgap (BG) for detection similarly decreases. Eventually this trade-off becomes infeasible as thermally generated carriers begin to overwhelm the expected photocurrent. These thermal effects are exacerbated when utilizing designs such as avalanche photodiodes which require cooling for a small BG design to have low noise. Conversely, a wider BG device enables room-temperature detection at the cost of sensitivity to long wavelength signals. As such, this work overcomes these limitations by decoupling photodetection from semiconductor bandgap using a combination of plasmonic excitation coupled into an avalanche diode with uniquely tuned impact ionization locations. Specifically, we investigate wide band plasmonic nanoantennas, connected to a GaAs avalanche heterostructure with a novel architecture, inspired by phototransistor designs. By tuning the impact ionization locations for the ideal coupling with the nanoantenna, we are able to perform BG agnostic photodetection. The design was simulated with CST Microwave studio plasmonic excitation and COMSOL Multiphysics to simulate impact ionization regions, bias voltages, and output currents. This work presents a novel approach to photodetection which will allow a greater diversity detection schemes, designs, and use-cases.