INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Electrodeposited Cu2ZnSnS4 thin Films
Autor/es:
M. VALDÉS; M. MODIBEDI; M.A. FRONTINI; M.VÁZQUEZ; T. HILLIE
Lugar:
Pretoria
Reunión:
Encuentro; 13th Topical Meeting of the International Society of Electrochemistry; 2013
Institución organizadora:
International Society of Electrochemistry
Resumen:
Cu2ZnSnS4 (CZTS) is a quaternary semiconductor compound that has recently emerged as one of the promising candidates for thin film photovoltaic devices. The advantages involve its direct band gap (1.45-1.50 eV) and high absorption coefficient (above 104 cm−1). Besides, all the constitutive elements in CZTS are abundant and environmentally friendly. Among the methods to produce CZTS thin films, electrochemical approaches present important features: they are cost-effective (mainly because they do not require high vacuum o high temperatures), they can be used in large and flexible substrates (even in intricate geometries) and they can be scaled-up into industrial production. In this work Cu2ZnSnS4 (CZTS) thin films have been prepared using Electrochemical Atomic Layer Deposition (E-ALD) and compared to one-step conventional constant potential electrodeposition. E-ALD is the electrochemical analog of atomic layer deposition and it is based on the alternating underpotential deposition (UPD) of the elements to form the compound semiconductor in a cycle. UPD is a surface limited phenomenon; the resulting deposit is generally limited to an atomic layer. When the UPD range is changed, the driving force is not sufficient to grow atoms on top of the underlying atoms; thus, each deposition cycle can form only a monolayer of heterogeneous elements, and the thickness of the deposit is controlled by the number of deposition cycles. Optimal deposition conditions were investigated using cyclic voltammetry (CV) on TCO, Au and Au/S covered electrodes. Then, based on CVs results, CZTS films were growth employing different E-ALD deposition cycles like Au/S/Cu/S/Zn/S/Sn/S to form the desired quaternary compound. The results were compared to those of conventional one-step electrodeposition performed at -1.1 V vs. Ag/AgCl during 1 hour. Other deposition parameters were also investigated in an attempt to optimize the stoichiometry. The crystal structure of the films was characterized by XRD and micro Raman spectroscopy, while the morphology, thickness, topography and elemental composition were addressed using FI-SEM, AFM and EDS.