Laser

The penetration depth of the laser light into the wafer depends on the energy respectively the wafelength of the laser light. The following figure shows the generation profile and the minority carrier concentration profile for FPC-, BPC- and BSP- mode of two lasers with quite different penetration depth:

- Infrared (IR: wavelength = 820nm) laser: penetration depth = 16 µm

- Deep infrared (SIR: wavelength = 1047nm) laser: penetration depth = 500 µm

The concentration profiles differe strongly for each mode, so obveosly the modes are sensetive to the diffusion length in different regions of the wafer. This allows to extract information on the depth dependance of the diffusion length respectively to distinguish between bulk and surface recombination processes.