Physical properties of CdS:Ga thin films synthesized by spray pyrolysis technique


Yilmaz S., POLAT İ. , OLGAR M. A. , Tomakin M., TORELI S. B. , BACAKSIZ E.

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, cilt.28, ss.3191-3199, 2017 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 28 Konu: 4
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1007/s10854-016-5908-0
  • Dergi Adı: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
  • Sayfa Sayıları: ss.3191-3199

Özet

This paper reports the investigation of physical properties of CdS:Ga thin films grown for the first time by a simple spray pyrolysis method as a function of Ga-doping level from 0 to 8 at.%. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive photoelectron spectroscopy, transmittance, photoluminescence, Hall effect and resistivity measurements are utilized to search for the structural, morphological, chemical, optical and electrical properties of as-prepared samples. XRD data confirm the presence of hexagonal structure with a strong (101) preferred orientation. SEM results show that the surface morphology varies significantly via Ga-doping, particularly 6 at.% doping level. Optical transparency is improved by the lower Ga-doping (2 and 4 at.%) whereas higher doping concentration (6 and 8 at.%) causes a poor transmission in the visible region. With respect to CdS (2.42 eV), the calculated band gap values at first enhances for 2 at.% Ga-doping and reaches to 2.43 eV. But, further increase in Ga-doping amount leads to a drop in the band gap value (2.39 eV) for 8 at.% Ga-doping. Electrical analyses display that 2 at.% Ga-doped CdS thin films exhibit a maximum carrier density and a minimum resistivity that are related to the substitutional incorporation of Ga3+ ions at Cd2+ ions. However, higher doping of Ga atoms into CdS gives rise to a gradual diminish in the carrier concentration and a rise in the resistivity. Based on all the data, it should be concluded that 2 at.% Ga-doped CdS thin films exhibit the best optical and electrical properties that can be used in the optoelectronic applications.