Growth of GaAs and AlGaAs on Si substrates by atomic hydrogen assisted MBE (H-MBE) for solar cell applications

The crystalline quality of both GaAs and AlGaAs films grown on Si substrates by atomic hydrogen-assisted low-temperature molecular beam epitaxy (H-MBE) technique have been studied using time-resolved photoluminescence method. An average minority carrier lifetime of τ=1.93 ns has been successfully obtained for n-Al_xGa_1-xAs (x=0.2) films on Si grown at a low-temperature of 330°C by H-MBE technique (n=2×10¹⁷ cm^-3), and was comparable to those grown on GaAs substrates by the conventional MBE. The role of atomic hydrogen in MBE growth process has been discussed based on the secondary ion mass spectroscopy (SIMS) analysis. The authors have also fabricated GaAs solar cell structures on Si substrates by their technique and their fundamental properties have been briefly discussed