Kinetics of surface-state laser annealing in Si by frequency-swept infrared photothermal radiometry

Frequency-swept ("chirped'') infrared photothermal radiometry was combined with conventional single-frequency modulation of an Ar ion laser beam to yi eld a quantitative study of the surface-state annealing processes induced b y the low-fluence laser beam on n- and p-type Si wafers. The appearance of a signal transient was found to be strongly dependent on the electronic qua lity of the wafer surface and was absent in the thermally oxidized p-Si waf er. The low-injection minority-carrier lifetimes and diffusion coefficients were not affected by the laser-surface interaction, but the surface recomb ination velocity strongly decreased with time of exposure. A two-trap rate model was advanced to explain the transient behavior in terms of surface-st ate annealing and carrier ejection. (C) 1999 American Institute of Physics. [S0003-6951(99)02017-3].