The Growth Mechanism of Nanometer-scale GaAs, InAs, and AlGaAs Whiskers

Freestanding nanometer-scale whiskers composed of GaAs, InAs, and AlGaAs were grown using organometallic vapor-phase epitaxy. We found two kinds of relationship between the growth rate of the whiskers and their width depending on the growth temperature. The relationship between the growth rate and the width of the whiskers at lower temperatures can be explained by the difference between the chemical potentials in the vapor phase and in the whisker (solid phase). The minimum width of the whiskers was around 1 nm for GaAs, 4 nm for InAs, and 9 nm for AlGaAs. The relationship between the growth rate and the width of the whiskers at higher temperatures can be explained by the process of surface migration of the source material near the whiskers. In both relationships, the growth rate depended on the amount of Au in the alloy droplets used as seeds for growth. This dependence indicates that there is an optimum amount of Au for whisker growth.