Among various trials on improving energy conversion efficiency of silicone based photo-voltaic cell, laser doping
casts promising future. Several research groups are suggesting their own methods for laser doping. Usually, doping laser
is injected inside of narrow phosphoric acid jet. The injected beam propagates through the jet and it grooves surface of
silicone cell. The laser energy also heats the silicone surface and phosphorous is penetrated through the surface. In this
work, we separate the grooving laser and heating laser. The silicone surface was grooved by a pulsed fiber laser. The
spot size of the laser was 50 μm. For surface measurement, grooved with of 200 μm was needed. To have the groove
width, we scanned the laser several times. SEM image of the grooved surface showed ripple of the surface. The
phosphoric acid was sprayed on the grooved surface. A fiber coupled cw diode laser heated the sprayed Si surface. After
heating, the Si was washed thoroughly by deionized water. The depth profile of penetrated phosphorous was examined
by using SIMS. The profile indicated that phosphorous was penetrated about 50 nm. Four point measurement of surface
resistance also indicated successful laser doping.
Thin organic film is coated on the laser absorbing layer. The organic material coated heat absorbing layer is closely
contacted with the substrate. When the laser is incident on the heat absorbing layer, the absorbing layer is expanded and
the organic film is transferred to the substrate. When the laser has Gaussian spatial profile, the profile of printed organic
material becomes non-uniform. We tried several laser beam profile shaping methods to get a clean and sharp printing.
The dependences of eliminated organic material profile from donor plate on the laser power, beam shaping method, and
the layer thickness are also investigated.