Monolithic GaN Digital Integrated Circuits for Ultrawide Temperature Range from 5 K to 800 K

This work demonstrates GaN devices and monolithic digital circuit implementations operating from cryogenic to extreme-high temperatures for ultra-wide-temperature electronics. Stable normally-off device operation and integrated circuit (IC) functionality are achieved through temperature-robust self-aligned (SA) and high-resistance (HR) passivated p-GaN technologies. Experimental results show reliable operation from 5 K to 800 K. The SA-HEMT threshold voltage (Vth) shows a total shift of 1.06 V within this range, while the on-state resistance escalates from 1.6 Ω·mm at 5 K to 11.4 Ω·mm at 800 K. The long-term stability is verified by continuous operation for 50 hours at both 5 K and 800 K, SA devices demonstrate a variation of around 10%. Monolithically integrated DCFL inverters and 101-stage ring oscillators are developed on the same GaN enhancement (E) and depletion (D)-mode platform. Between 5-800 K, the inverters exhibit logic-low output voltages (Vol) ranging from 0.01 to 0.08 V for SA-based circuits and reaching 0.22 V for HR-based circuits at high temperatures, with noise margins (NM) of 2.0 to 2.8 V. The SA-based ring oscillators maintain oscillation frequencies above 10 MHz and propagation delays below 400 ps/stage across the entire temperature range. This result provides the first experimental demonstration of GaN devices and monolithic digital ICs operating continuously from cryogenic to extreme high-temperature conditions, enabling robust high-density electronic systems for extreme environments.