July 16, 2007 – First Nano, a division of CVD Equipment Corp., has unveiled two solid source deposition systems specifically for producing semiconducting nanowires, saying that solid sources such as gallium and zinc powders are less expensive and safer than conventional metal organic sources used in metal organic vapor deposition chemical vapor deposition (MOCVD) methods for manufacturing LEDs.
The new ET2000-SS and ET3000-SS tools are specifically designed to accommodate “vapor-solid” (VS) and “vapor-liquid solid” (VLS) CVD methods of nanowire deposition. For ZnO materials (an alternative to GaN used for blue LEDs and lasers), the source is heated to ~900°C to vaporize the source powders, and then dropped to ~800°C when the sample is placed in the chamber, which typically leaves a nonuniform area for the substrate and a narrow process area for sample placement.
First Nano’s tools, however, provide distinct temperature zones and separate closed loop temperature control for better temperature control of the source material and substrate temperature uniformity, the company claims. It claims growth of ZnO nanowires grown on a 2″ sapphire wafer, and up to 25-microns long grown on carbon flakes (see image, below).