Abstract
Nanometer-size free-standing GaAs whiskers are characterized by a sub-picosecond lasersystem. These whiskers can be grown by a reduced-pressure metal-organic vapor-phase epitaxy.Photoluminescence measurements of the GaAs whiskers show a spectral blue shift andalso a polarization anisotropy due to the two-dimensional quantum confinement of the carriers.However, the spectral blue shift is much smaller than the lowest level energy expectedby the square-potential confinement. This suggests the importance of the surface depletionpotential, which is inherently caused by the surrounding air. The influence of the surface layercan be clarified by the experiments on the surface recombination velocity of the whisker. Surfacetreatment with sulphur solution comfirms the importance of the surface state. The profileof the surface depletion potential can be estimated from the analysis of the recombinationrate. Thus the time-resolved photoluminescence measurement is quite useful for understandingthe surface state of the whisker.
