THz emission from GaSb samples with modified surface stoichiometry

We report on the terahertz emission from GaSb surfaces with thermally modified surface stoichiometry. The thermal treatment increases significantly the THz emission from the GaSb samples. For optimal conditions, namely an annealing temperature of 500/spl deg/C, the emission is comparable to the emission from n-doped GaAs. The THz emission is due to the acceleration of carriers in a surface field, caused by a surface decomposition. The surface decomposition was confirmed by the observation of Sb coherent phonons in pump-probe experiments.