Sol–gel SZO/p-Si heterojunction solar cell elaboration and physical study

In this paper, the thickness effect of tin-doped zinc oxide (SZO) thin films on structural, morphological, optical, and electrical properties have been investigated for optimal SZO/p-Si heterojunction. For that, a series of SZO films were deposited on glass substrates by the sol–gel spin coating method at different cycles (5, 10, 15, 20, and 25) with a concentration of Sn doping fixed at 5%. The X-ray diffraction exhibits that all films are polycrystalline with hexagonal würtzite structure highly oriented along the c axis. The surface morphology visualized by scanning electronic microscopy (SEM) and atomic force microscopy (AFM) analysis shows a homogeneous granular structure, less rough, with a grain size which increases with the film thickness. UV–Visible spectroscopy shows a good optical transmittance of about 90% in the visible range and a high absorption in the UV domain, the maximum value of gap energy is 3.24 eV. Hall effect measurements reveal that electrical resistivity is limited both by the density and the mobility of the charge carriers according to the thickness of the elaborated films. Finally, the SZO/p-Si heterojunction that we elaborated showed a rectification behavior with an I ON / I OFF ratio of 12.92 at 2 V, a turn-on voltage of 3.24 V and an ideality factor of 6.91 in dark. Under illumination, the structure shows the following photoelectric parameters I SC = 1.12 × 10 - 7 A, V OC = 0.39 V, and FF = 30.82%.