Electronic structure of nanometer-scale GaAs whiskers

We report a theoretical study of the electronic structure of GaAs nanowhiskers, grown in the [111] direction with hexagonal cross section, based on a tight binding approach. It is shown that the band structure of the GaAs nanowhiskers shifts from a direct band gap to an indirect band gap when the lateral size of the nanowhiskers becomes smaller than a certain value. The effective masses of the electrons and holes are shown to increase with decreasing the nanowhisker lateral size. It is also shown that the light-hole states appear to be at the top of the valence bands. The electrical and optical properties of the nanowhiskers are discussed in terms of the results of the calculations. (C) 2002 American Institute of Physics.