Record performance of nitride-based resonant tunneling diodes

Resonant tunneling diodes (RTDs) are one potential answer to the growing demand for high power, compact millimeter-wave and terahertz sources, which have applications in medicine, imaging and more.

RTDs rapidly transport electrons using quantum mechanical tunneling. Currently, most applications employ III-arsenide-based RTDs due to their excellent frequency performance. However, arsenide-based RTDs are limited by their low power output.

In an attempt to increase this output power, Growden et al. grew III-nitride-based RTDs, specifically GaN-based RTDs. The wider bandgaps and higher thermal conductivity of III-nitride semiconductors permit a higher operational voltage and current density.

With GaN-based RTDs, the authors achieved record peak-to-valley current ratio and switching speeds for any nitride-based RTD to date, bringing these devices a step closer to high power and high frequency applications.

“Our study has shown that GaN-based RTDs are not inherently slow, as some had posited,” said author Tyler Growden. “Further, this work shows that nitride-based RTDs may have the potential to surpass the output power limitations of InGaAs/AlAs or InAs/AlSb RTDs with similar frequency performance.”

Previously, achieving a high yield of operational tunneling-based devices has been difficult. The authors fabricated hundreds of GaN-based RTDs from a sample grown by plasma-assisted molecular beam epitaxy, improving both the yield and the repeatability of the process. They credit this improvement to a combination of pre-growth sample preparation, highly uniform growth and monitoring all surfaces during each step of the fabrication process.

Next, to further increase the output power of GaN-based RTDs, the authors will figure out how to increase the peak current density of the devices without lowering the peak-to-valley current ratio.

Source: “Superior growth, yield, repeatability, and switching performance in GaN-based resonant tunneling diodes,” by Tyler A. Growden, David F. Storm, Evan M. Cornuelle, Elliott R. Brown, Weidong Zhang, Brian P. Downey, Jason A. Roussos, Nicholas Cronk, Laura B. Ruppalt, James G. Champlain, Paul R. Berger, and David J. Meyer, Applied Physics Letters (2020). The article can be accessed at https://doi.org/10.1063/1.5139219 .