Gallium doped ZnO for thin film solar cells

Gallium doped ZnO films with resistivities as low as 0.4x10(-3) Omegacm were grown by rf-magnetron sputtering. For a given thickness the sputter time to deposit gallium doped ZnO was in average only two thirds of that needed to deposit aluminium doped ZnO. Despite the higher sputter rates for ZnO:Ga the electrical transport properties were almost the same for both type of films with mobilities around 10cm(2)/Vs and net carrier concentrations of n = 4x10(20) cm(-3). The band gap was determined to be E-g = 3.24 eV. Solar cells prepared with Cu(In,Ga)(S,Se)(2) absorber layers exhibited efficiencies of up to 13.6%.