Growth and characterization of Ge-substituted Cu2ZnSnSe4 thin films

摘要: Abstract The incorporation of germanium into Cu2ZnSn(S,Se)4 thin films is gaining a massive attention because its potential to tailor the properties kesterite absorbers resulting in high efficiency solar photovoltaic devices. present work reports growth Cu2Zn(Sn,Ge)Se4 (CZTGSe) by during deposition precursor film consisting multiple stacks (Sn/Se/Ge/Se/ZnSe/Se/Cu/Se). were sequentially evaporated onto soda lime glass substrates held at 100 °C vacuum. Subsequent selenization horizontal tubular furnace 425 °C led formation single phase Cu2Zn(Sn0.7Ge0.3)Se4 films. X-ray diffraction pattern stacked layers selenized revealed with preferred orientation along (112) plane. Rietveld refinement corroborated kesterite-type CZTGSe having tetragonal structure lattice constants = 5.678 A and c = 11.304 A. Raman measurements performed using excitation wavelengths confirmed Secondary ion mass spectroscopy (SIMS) depth profiles illustrated uniform distribution constituent elements FESEM images showed relatively spherical grains 100–150 nm size. Optical absorption studies an optical band gap 1.19 eV coefficient (> 104 cm−1). exhibited p-type conductivity resistivity 69.8 Ω cm, mobility 38.35 cm2(Vs)−1 carrier concentration 2.33 × 1015 cm−3.