Improved diode properties in zinc telluride thin film-silicon nanowire heterojunctions


AKSOY F., AKGÜL G., Gullu H. H. , ÜNALAN H. E. , TURAN R.

PHILOSOPHICAL MAGAZINE, cilt.95, ss.1164-1183, 2015 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 95 Konu: 11
  • Basım Tarihi: 2015
  • Doi Numarası: 10.1080/14786435.2015.1026296
  • Dergi Adı: PHILOSOPHICAL MAGAZINE
  • Sayfa Sayıları: ss.1164-1183

Özet

In this study, structural and optoelectronic properties and photodedection characteristics of diodes constructed from p-zinc telluride (ZnTe) thin film/n-silicon (Si) nanowire heterojunctions are reported. Dense arrays of vertically aligned Si nanowires were successfully synthesized on (110)-oriented n-type single crystalline Si wafer using simple and inexpensive metal-assisted etching (MAE) process. Following the nanowire synthesis, p-type ZnTe thin films were deposited onto vertically oriented Si nanowires via radio frequency magnetron sputtering to form three-dimensional heterojunctions. A comparative study of the structural results obtained from X-ray diffraction and Raman spectroscopy measurements showed the improved crystallinity of the ZnTe thin films deposited onto the Si nanowire arrays. The fabricated nanowire-based heterojunction devices exhibited remarkable diode characteristics and enhanced optoelectronic properties and photosensitivity in comparison to the planar reference. The electrical measurements revealed that the diodes with nanowires had a well-defined rectifying behaviour with a rectification ratio of 10(4) at +/- 2V and a relatively small ideality factor of n=1.8 with lower reverse leakage current and series resistance at room temperature in dark condition. Moreover, an open-circuit voltage of 100mV was also observed under illumination. Based on spectral photoresponsivity measurements, the nanowire-based device exhibited a distinct responsivity and high detectivity in visible and near-infrared (NIR) wavelength regions. The device characteristics observed here offer that the fabricated ZnTe thin film/Si nanowire-based p-n heterojunction structures will find important applications in future and will be a promising candidate for high-performance and low-cost optoelectronic device applications, NIR photodedectors in particular.