DARPA-supported researchers have developed a new approach for synthesizing ultrathin materials at room temperature—a breakthrough over industrial approaches that have demanded temperatures of 800 degrees Celsius or more. The advance opens a path to creating a host of previously unattainable thin-film microelectronics, whose production by conventional methods has been impossible because many components lose their critical functions when subjected to high temperatures. The new method, known as electron-enhanced atomic layer deposition (EE-ALD), was recently developed at the University of Colorado, Boulder (CU) as part of DARPA’s Local Control of Materials Synthesis (LoCo) program. The CU team demonstrated room-temperature deposition of silicon and gallium nitride—linchpin elements in many advanced microelectronics—as well as the ability to controllably etch specific materials, leading to precise spatial control in three dimensions. Such a capability is critical as the demand grows for ever-smaller device architectures.