Cryogenic In0.8Ga0.2As Quantum-Well High-Electron Mobility Transistors from Lowpower Quantum Computing to Tera-Hz Applications

초록

We present cryogenic In<inf>0.8</inf>Ga<inf>0.2</inf>As QW HEMTs with a gate length (L<inf>g</inf>) of 35 nm, achieving a record combination of low-power and high-frequency performance. A meticulous modeling of source resistance (R<inf>s</inf>) incorporating ballistic channel resistance (R<inf>ball</inf>) - provides key insights for advancing low-power quantum computing and terahertz (THz) applications. At 4 K, the fabricated device exhibits exceptional performance metrics, including a minimum subthreshold-swing (S<inf>min</inf>) of 4.41 mV/dec., a g<inf>m-max</inf> of 2.49 mS/μ m, and the highest record f<inf>T</inf> of 813 GHz, with an average gain-bandwidth product (f<inf>avg</inf>) of 810 GHz. These results stem from a tightly controlled gate-recess process, minimizing the side length (L<inf>side</inf>) to below 20 nm. Delay-time analysis indicates further THz performance can be achieved by scaled L<inf>g</inf> below 20 nm and reducing fringing gate capacitance (C<inf>g-fringe</inf>) by 20%. This work demonstrates the potential of cryogenic In<inf>0.8</inf>Ga<inf>0.2</inf>As QW HEMTs to revolutionize quantum computing and THz electronics © 2025 JSAP.