Characterization of ZnGeAs2 thin films produced by pulsed laser deposition

Abstract

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, μp, 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.