ZnGeAs2 thin films properties: A potentially useful semiconductor for photovoltaic applications

We have studied the chalcopyrite compound ZnGeAs₂ to access its potential as a novel photovoltaic material. Thin films of ZnGeAs2 have been produced by pulsed laser deposition.The films are deposited at 315°C and are amorphous. They crystallize above 450°C and improve in crystallinity up to and including 600°C. At that temperature the Hall mobility is 55 ± 2 cm²/Vs, which is within uncertainty to the highest mobility ever reported for this material. We find a rather high carrier concentration, of order 10¹⁸ - 10¹⁹ for the annealed films, presumably due to the presence of Zn vacancies. The material is an effective light absorber, with an absorption coefficient of order 10⁴ 1/cm at 1.2 eV. These properties suggest ZnGeAs₂ may be used to produce cost effective and efficient solar cells.