Technical Insight
GaAs Quantum Dots Produced by Liquid Droplet Epitaxy (News from Japan)
A way to fabricate large numbers of GaAs quantum dots of uniform size and shape has been developed by a joint team from the National Research Institute for Metals and the University of Tokyo. The method is named liquid-droplet epitaxy since the procedure involves spraying the starting materials to yield an arrangement of GaAs dots shaped like round droplets of water. Each tiny island of GaAs is just 520 nm in diameter and acts as a quantum dot, trapping electrons in a confined space and promising a future of extremely fast, low-power computing. The grains also emit light at room temperature, suggesting new types of devices for the information society. Starting with an AlGaAs thin film grown on GaAs, a liquid solution of gallium is sprayed onto the surface, creating numerous Ga droplets. Then As is sprayed over the wafer, creating GaAs quantum dots of common size and shape. Such features are thought to offer the potential for semiconductor lasers that emit light with one-hundredth the current of existing devices and quantum computers that operate at extremely fast speeds.
