Characterization of ZnGeAs2 thin films produced by pulsed laser deposition

We have characterized the properties of chalcopyrite ZnGeAs₂ thin films produced over a wide range of growth conditions using pulsed laser deposition. By using a Zn-enriched target, stoichiometric films could be produced up to a substrate temperature of 315°C; above which the films were Zn and As deficient. Optical absorption measurements indicate that bandgap of the ZnGeAs₂ thin films is direct with a value of ~1.15 eV. Hot point probe indicate that the as-deposited and annealed thin films are both p-type. Hall measurements confirm this and also indicate that the carrier mobility, ¿_p, is over 50 cm²/V·sec in the 600°C annealed samples. Channeling Rutherford Backscattering Spectroscopy (RBS) indicates that the structurally best films are achieved after 450°C annealing with a channeling yield, ¿_min, of 50%. Our results, in combination with the observation that the constituents are abundant elements, suggest that ZnGeAs₂ is an ideal candidate for photovoltaic applications.