Silicon solar cells realized by laser induced diffusion of vacuum-deposited dopants

Abstract

A technique for solar cell preparation based on vacuum deposition of thin films of dopants on silicon, followed by irradiation with a high‐energy (∼1.5 J/cm2) ruby laser pulse is described. Several dopants like phosphorus, antimony,bismuth,aluminium,gallium, and indium have been investigated. Electrical and Rutherford backscattering measurements indicate that the dopant is dissolved in the silicon and becomes electrically active, as a result of the irradiation. The P‐N junctions which are formed are shallow (depth <4000 Å) but heavily doped, since after the laser treatment the solubility of the dopant is generally higher than after a thermal diffusion. Therefore good diode characteristics can be achieved by this simple method, and solar cells up to 14 % efficiency under AM1 (air mass 1) illumination have been realized using dopants like phosphorus, antimony,bismuth,aluminium, or gallium.