A Surface Photovoltage Study of Surface Defects on Co-Doped TiO2 Thin Films Deposited by Spray Pyrolysis

Abstract

Surface photovoltage (SPV) spectroscopy is a powerful tool for studying electronic defects on semiconductor surfaces, at interfaces, and in bulk for a wide range of materials. Undoped and Cobalt-doped TiO 2 (CTO) thin films were deposited on Crystalline Silicon (c-Si) and Flourine doped Tin oxide (SnO 2 :F) substrates by chemical spray pyrolysis at a substrate temperature of 400˝C. The concentration of the Co dopant in the films was determined by Rutherford backscattering spectrometry and ranged between 0 and 4.51 at %. The amplitude of the SPV signals increased proportionately with the amount of Co in the films, which was a result of the enhancement of the slow processes of charge separation and recombination. Photogenerated holes were trapped at the surface, slowing down the time response and relaxation of the samples. The surface states were effectively passivated by a thin In 2 S 3 over-layer sprayed on top of the TiO 2 and CTO films.

Surface Photo-Voltage (SPV) and Photo electrochemistry (PEC) on TiO2

“…The in phase (X-signal) and out of phase (Y-signal, 90 shift) give information about the instantaneous charge collected on the sample surface/quartz + FTO electrode interface and the time response of the charge separation respectively [11]. The SPV amplitude is the square root of the sum of the squares of the X and Y signals [12,13].…”

Synthesis of MgO Coating Gd2O3 Nanopowders for Consolidating Gd2O3-MgO Nanocomposite with Homogenous Phase Domain Distribution and High Mid-Infrared Transparency

“…Therefore, it is significant to synthesize nanocomposite powders with good dispersion and homogenous constituent phase distribution. Among the varied methods for producing nanopowders, such as spray pyrolysis [21,22], glycine-nitrate process [23,24], sol-gel combustion [24], and hydrothermal method [25], the sol-gel combustion method has always been favored, mainly due to its reduced synthesis temperature and the atomic-level mixing of starting reactants [8,17,26]. However, the properties of nanocomposite powders prepared by sol-gel combustion method such as particle size and dispersion are influenced by various factors such as starting reactants, fuel type, and equivalence ratio Φ. Additionally, the sol-gel process has long powder preparation cycles which are not conductive to batch production.…”

Optoelectronic properties of In2S3 thin films measured using surface photovoltage spectroscopy

“…There were a small number of reports on SPV studies of In 2 S 3 films [6][7][8][9][10]. However, to the best of our knowledge, the use of the SPV is to find the minority carrier diffusion length of polycrystalline In 2 S 3 thin films was not performed previously.…”