Cryogenic GaN Monolithically ICs based on Hydrogen Treatment Technology

Cryogenic electronics, operating from 77 K down to the millikelvin regime, requires device technologies that overcome the fundamental limitations of Si CMOS, such as dopant freeze-out. This work presents an innovative approach to realizing monolithic GaN integrated circuits (ICs) by applying an etching-free hydrogen passivation technology to successfully fabricate enhancement-mode (E-mode) p-GaN HEMTs. These devices demonstrate remarkable thermal stability across an extremely wide temperature range, maintaining stable operation from 5 K to 250 K. Over this range, the threshold voltage shift (ΔVth) remains less than 0.2 V, with a minimum subthreshold swing (SS) of only 24 mV/dec at 5 K, confirming excellent electrostatic control. Utilizing these devices, a GaN direct-coupled FET logic (DCFL) inverter is demonstrated, exhibiting stable static and dynamic operation at 5 K. The inverter achieves an outstanding noise margin of 5.45 V at a VDD of 6 V and demonstrates operation up to a maximum frequency of 1 MHz. This research validates the potential of GaN-based cryogenic ICs as a compact, high-power-density, and highly stable solution for advanced low-Temperature electronic systems.