DARPA and BAE Systems tackle the heat holding next-gen GaN electronics

BAE Systems is moving into the second phase of a DARPA program aimed at solving one of the most persistent limitations in high-power radio-frequency electronics. Heat. BAE Systems’ FAST Labs research organization has completed Phase 1 of DARPA’s Technologies for Heat Removal in Electronics at the Device Scale (THREADS) program and has been selected to continue into Phase 2. The work focuses particularly on gallium nitride (GaN) devices, which are already widely used in high-performance radar, electronic warfare, and communications systems. The problem is straightforward in principle but difficult to solve. Increasing the power of an RF transistor generates more heat. If that heat cannot be removed efficiently, the transistor’s performance and reliability suffer. As a result, electronics can operate below their theoretical power limits. DARPA created THREADS to attack the problem inside the device itself, rather than simply adding larger conventional cooling systems around it. The agency says the program targets two major challenges. Reducing thermal resistance within the transistor while preserving electrical performance, and efficiently moving heat away from high-power transistor regions without degrading RF performance. Why GaN matters GaN is a wide-bandgap semiconductor that has become increasingly important for military RF electronics. Compared with older semiconductor technologies, it can operate at higher power densities and frequencies, making it particularly useful for modern active electronically scanned array (AESA) radars and electronic-warfare systems. DARPA has previously noted that GaN already provides more than a fivefold improvement in power density compared with earlier transistor technologies, but that much more could theoretically be achieved if engineers can overcome the heat problem. This is important because RF power directly affects what systems such as radar and communications equipment can accomplish. More usable RF power can potentially mean stronger signals, greater detection distances, or more capable electronic effects. DARPA’s current description of THREADS targets an eightfold reduction in thermal resistance and power densities of up to 81 W/mm for X-band transistor and power-amplifier test devices. From heat problem to longer-range radar The potential operational payoff is substantial. DARPA has previously estimated that solving the thermal limitations could increase radar range by two to three times. The agency’s more recent update says THREADS performers achieved approximately a fivefold increase in RF power density over today’s state of the art during Phase 1, corresponding to roughly a doubling of radar range while maintaining the reliability required for operational use. That doesn’t mean every radar using THREADS technology will automatically double its range. Radar performance depends on many factors, including antenna characteristics, frequency, target size, atmospheric conditions and signal processing. Instead, the figures illustrate why solving thermal limitations at the semiconductor level could have an outsized effect on complete systems. BAE Systems is conducting its own work at its Microelectronics Center in Nashua, New Hampshire, where the company already develops and manufactures GaN and gallium-arsenide integrated circuits for defense applications. Its THREADS effort involves collaboration with Modern Microsystems and researchers at Penn State, Stanford, Notre Dame and the University of Texas at Dallas. Building on earlier thermal breakthroughs THREADS is also part of a longer effort to make GaN electronics better at handling heat. DARPA previously demonstrated a GaN-on-diamond transistor through its Near Junction Thermal Transport program, exploiting diamond’s exceptionally high thermal conductivity to reduce temperatures near the transistor junction. THREADS takes the broader challenge further, looking at materials, device structures, and ways of extracting heat directly at the transistor level. For BAE Systems, entering Phase 2 means moving beyond the initial research toward further development and validation of its approach. The ultimate goal is not simply a cooler transistor. It is an RF device that can generate substantially more power without becoming larger, less reliable, or thermally constrained. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Kaif Shaikh is a journalist and writer passionate about turning complex information into clear, impactful stories. His writing covers technology, sustainability, geopolitics, and occasionally fiction. A graduate in Journalism and Mass Communication, his work has appeared in the Times of India and beyond. After a near-fatal experience, Kaif began seeing both stories and silences differently. Outside work, he juggles far too many projects and passions, but always makes time to read, reflect, and hold onto the thread of wonder.