GaAs heteroepitaxial growth on Si for solar cells

Abstract
Thermal annealing effects on the reduction of dislocation density in GaAs on Si substrates were investigated. The dislocation density in GaAs films grown on Si substrates by metalorganic chamical vapor deposition was reduced by in situ thermal annealing to 2×106/cm2. We have found that the cooling and heating cycle of the GaAs film is most important factor in reducing the dislocation density in thermal annealing. Solar cells fabricated using GaAs films with 5×106/cm2 etch pit density have 18% conversion efficiency for the active area under AM1.5 simulated illumination.