Surface Modification of N-Gaas Semiconductor with Metalloporphyrin/Polysiloxane Matrices Effect of Modification on: Band-Edge Positions, Short Circuit Current and Surface Stability in Aqueous Photoelectrochemistry

Surface Modification of N-Gaas Semiconductor with Metalloporphyrin/Polysiloxane Matrices Effect of Modification on: Band-Edge Positions, Short Circuit Current and Surface Stability in Aqueous Photoelectrochemistry

Muayad Masoud Mahmoud Masoud Semiconductor (SC) surfaces are currently being investigated as catalysts for solar energy utilization. In one of the most important applications of photoelectrochemical (PEC) cells, SCs are used as photocatslysts for water splitting. Unfortunately, there is no available SC that satisfies all the features of a good SC catalyst for PEC water splitting. Therefore, it is desired that the band edges of SC be shifted, mainly positively, to improve the charge transfer processes at the surface and to enhance the SC surface resistance against deterioration. We have developed a new technique to tailor the positions of SC band edges. Tetra (-4-pyridyl) porphyrinatomanganese(III)sulfate (MnP), existing in the form of Mn"' and Mn" ion mixture, was embedded into a polysiloxane polymer matrix and was attached to the surfaces of n-GaAs wafers. The nGaAs/polymer/MnP system was annealed under nitrogen and used for photoelectrochemical study in water/LIC104 and Fe(CN)63-/Fe(CN)64- as a redox couple. The results indicated a positive shift in the value of the flat-band potential of the SC due to the presence of the MnP. Muayad Masoud Mahmoud Masoud Supervisors Prof. Hikmat S. Hilal Dr. Samar Al-Shakshir 2001 Zajel / An-Najah National University