Effect of the Ti/Si ratio of spin coating solutions on surface passivation of crystalline silicon by TiO_x–SiO_xcomposite films

Abstract

Passivation films or antireflection coatings are generally prepared using costly vacuum or high-temperature processes. Thus, we report the preparation of TiOx–SiOx composite films by novel spin coatable solutions for the synthesis of low-cost passivation coating materials. The desired films were formed by varying the mixing ratios of TiOx and SiOx, and the resulting films exhibited excellent surface passivation properties. For the p-type wafer, an optimal effective surface recombination velocity (Seff) of 93 cm/s was achieved at , while a surface recombination current density (J0s) of 195 fA/cm2 was obtained. In contrast, for the n-type wafer, an Seff of 27 cm/s and a J0s of 38 fA/cm2 were achieved at . This excellent surface passivation effect could be attributed to the low interface state density and high positive fixed charge density. Furthermore, the thickness of the interfacial SiOx layer was determined to be important for obtaining the desired surface passivation effect.

Optimization of a Solution-Processed TiOx/(n)c-Si Electron-Selective Interface by Pre- and Postdeposition Treatments

“…While negative V fb and positive Q f of −0.44 V and 4.84 × 10 11 cm –2 were calculated for the annealed sample, respectively, the high current leakage across the device precluded the extraction of D it via conductance-based methods to quantify the chemical passivation level. There have been reports about the potential presence of both positive and negative Q f in the TiO x layer, which in fact depends on the chemicals employed in the fabrication process, the Ti precursor, the deposition technique and conditions, as well as pre- and postdeposition treatments. ,, Our observations concerning TDIP (the titanium precursor used in this study) ability to generate substoichiometric TiO x and a negative V fb as the evidence of positive Q f are aligned with the results reported in ref . The KPFM technique is used to measure the contact potential difference (CPD) between the tip and the surface of the sample.…”