Effects of free carriers on piezoelectric nanogenerators and piezotronic devices made of gan nanowire arrays

Chao Hung Wang, Wei Shun Liao, Nai Jen Ku, Yi Chang Li, Yen Chih Chen, Li Wei Tu, Chuan Pu Liu

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

This study investigates the role of carrier concentration in semiconducting piezoelectric single-nanowire nanogenerators (SNWNGs) and piezotronic devices. Unintentionally doped and Si-doped GaN nanowire arrays with various carrier concentrations, ranging from 10 17 (unintentionally doped) to 10 19 cm-3 (heavily doped), are synthesized. For SNWNGs, the output current of individual nanowires starts from a negligible level and rises to the maximum of ?50 nA at a doping concentration of 5.63 x?10 18 cm-3 and then falls off with further increase in carrier concentration, due to the competition between the reduction of inner resistance and the screening effect on piezoelectric potential. For piezotronic applications, the force sensitivity based on the change of the Schottky barrier height works best for unintentionally doped nanowires, reaching 26.20 ?1.82 meV nN ?1 and then decreasing with carrier concentration. Although both types of devices share the same Schottky diode, they involve different characteristics in that the slope of the current-voltage characteristics governs SNWNG devices, while the turn-on voltage determines piezotronic devices. It is demonstrated that free carriers in piezotronic materials can infl uence the slope and turn-on voltage of the diode characteristics concurrently when subjected to strain. This work offers a design guideline for the optimum doping concentration in semiconductors for obtaining the best performance in piezotronic devices and SNWNGs.

Original languageEnglish
Pages (from-to)4718-4725
Number of pages8
JournalSmall
Volume10
Issue number22
DOIs
Publication statusPublished - 2014 Nov 26

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Biomaterials
  • Chemistry(all)
  • Materials Science(all)

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