Effect of Ni on the growth and photoelectrochemical properties of ZnS thin films

Chao Ming Huang, Lung Chuan Chen, Guan Ting Pan, Thomas C.K. Yang, Wei Sheng Chang, Kong Wei Cheng*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

55 Scopus citations

Abstract

Undoped and Ni-doped ZnS thin film photoelectrodes were prepared using the chemical bath deposition process. X-ray diffraction patterns of a hexagonal wurtzite structure with preferential orientation along the (0 0 8) plane appeared on undoped ZnS films. An increase in the molar ratios of Ni, x, in the starting solution resulted in a decrease in the intensity of the (0 0 8) plane. Images from a scanning electron microscope revealed a drastic change of the surface morphology of the Ni-doped ZnS film due to ion-by-ion deposition. The energy band gaps of Ni-doped ZnS thin films shifted to lower energy levels between 3.34 and 3.01 eV. Moreover, increasing the Ni ratio led to a shift in the flat-band potential of the film towards a more positive value compared to that of ZnS. The Ni-doped ZnS films experienced a conversion from n-type to p-type when the molar ratio of Ni changed from 0.003 to 0.005. The photocurrent densities of Ni-doped ZnS film (x = 0.003) reached 3.74 mA cm-2 at an external potential of 1.5 V versus a Pt electrode and exhibited a threefold enhancement of photocurrent density compared to pure ZnS. A cathodic photocurrent of 0.82 mA cm-2 at an external potential of -1.5 V was obtained for a Ni concentration of x = 0.005. Crown

Original languageEnglish
Pages (from-to)156-162
Number of pages7
JournalMaterials Chemistry and Physics
Volume117
Issue number1
DOIs
StatePublished - 15 09 2009

Keywords

  • Chemical synthesis
  • Electrical properties
  • Semiconductors
  • Thin films

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