Polycrystalline CdTe solar cells by pulsed laser deposition

Polycrystalline CdS/CdTe heterojunctions have been grown by pulsed laser-driven physical vapor deposition (LDPVD) using an XeCl excimer laser at 308 nm. The LDPVD process accommodates thin-film growth at low substrate temperatures (⩽300°C), while permitting considerable control over the physical conditions of the deposition plume. The congruent evaporation provides good film stoichiometry and the use of multiple targets facilitates heterojunction fabrication in a single vacuum chamber. Polycrystalline films were grown on alkali-free glass and on SnO₂-coated glass from pressed powder targets in a vacuum of ~5×10^-6 torr. Optimum growth occurred near 280°C with growth rates of ~0.5 Å/pulse. Devices were fabricated on the films after post-growth annealing and characterized by I-V and spectral quantum efficiency measurements