Reduced series resistance solar cell - has semiconductor surface melted and re-crystallised using high energy short duration laser pulses

摘要

In the mfr. of solar cells the diffused layers of semi- conducting material are irradiated before deposition of a grid and an anti-reflecting layer. The radiation consists of high energy pulses (energy density approx. 1 J/sq.cm.) of very short duration (less than 50 ns) produced by a ruby laser (wavelength 6943 Angstroms). The energy of the beam, absorbed in a depth of 1000 - 2000 Angstroms, is sufficient to superficially melt the semiconductor. The melted zone recrystallises in a very short time (100 ns) in a process similar to epitaxy from the liquid phase. This process reduces the surface resistance of the material leading to a reduction in the series resistance of a solar cell incorporating the material. The need for a special grid is avoided thus eliminating a costly mfr. stage.