Researchers at NIST and the Colorado School of Mines are investigating semiconductor nanowires to improve the manufacturing of tiny devices like LEDs and chemical sensors. These wires are incredibly small, with some layers only a few nanometers thick, and require precise control over how different atoms are arranged during growth. The team used a technique called molecular beam epitaxy to build the wires with embedded layers that trap light-emitting particles, known as quantum wells. Their goal is to ensure these wells stay compact and uniform, as any spreading of materials can cause the device to emit light inefficiently.
To see inside the wires without damaging them, the scientists employed a method called laser-assisted atom probe tomography, which creates a 3D map of the chemical composition. This analysis revealed that the internal layers often form as thin conical shells rather than flat discs, and that slight changes in growth conditions can cause these layers to disperse invisibly. While the study highlighted challenges in measuring certain elements accurately, the detailed maps of the metal components provide essential guidance for building more reliable nanoscale devices in the future.
Source: https://www.nist.gov/news-events/news/2013/12/probing-inner-secrets-nanowires
Keywords: molecular beam epitaxy, atom probe tomography, quantum wells
