Determination of minority carrier lifetimes in n-type GaAs and their implications for solar cells

A comprehensive study of n-type lifetimes versus doping concentration in selenium doped n-GaAs is detailed. By observing the photoluminescence delay of double heterostructure it is found that for N_D<10¹⁸ cm^-3 the minority carrier lifetime is dominated by radiative recombination and photon recycling, and that both are also important for all doping concentrations studied. For N_D>10¹⁸ cm ^-3, the authors are able to set an upper limit on the Auger recombination coefficient. The B coefficient in n-GaAs is deduced to about 2.0×10^-10 cm³/s for lowly doped material, but it decreases with increasing doping concentration. These results are used to project efficiencies of GaAs solar cells using analytical models