Optical Properties of Indium Doeped ZnO Nanowires

Tsung-Shine Ko,Sin-Liang Ou,Der-Yuh Lin,Tz-Min Yang,Kuo-Sheng Kao

doi:10.1155/2015/760376

Abstract

We report the synthesis of the ZnO nanowires (NWs) with different indium concentrations by using the thermal evaporation method. The gold nanoparticles were used as the catalyst and were dispersed on the silicon wafer to facilitate the growth of the ZnO NWs. High resolution transmission electron microscopy confirms that the ZnO NWs growth relied on vapor-liquid-solid mechanism and energy dispersion spectrum detects the atomic percentages of indium in ZnO NWs. Scanning electron microscopy shows that the diameters of pure ZnO NWs range from 20 to 30 nm and the diameters of ZnO:In were increased to 50–80 nm with increasing indium doping level. X-ray diffraction results point out that the crystal quality of the ZnO NWs was worse with doping higher indium concentration. Photoluminescence (PL) study of the ZnO NWs exhibited main photoemission at 380 nm due to the recombination of excitons in near-band-edge (NBE). In addition, PL results also indicate the slightly blue shift and PL intensity decreasing of NBE emission from the ZnO NWs with higher indium concentrations could be attributed to more donor-induced trap center generations.

Highlights

Zinc oxide (ZnO) is one of the most favorable materials for blue/UV-associated optoelectronic devices and excitonrelated device applications due to a wide band gap (3.37 eV) at room temperature and a large excitonic binding energy (60 meV) in comparison with GaN (28 meV) [1]
The influence of the indium concentration on structural and optical properties of ZnO and ZnO:In NWs were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), selected area electron diffraction (SAED), and photoluminescence (PL)
The diameters of pure ZnO NWs range from 20 to 30 nm and the diameters of ZnO:In with different indium doping level were in the range of 20–50 and 20–80 nm, respectively

Summary

Introduction

Zinc oxide (ZnO) is one of the most favorable materials for blue/UV-associated optoelectronic devices and excitonrelated device applications due to a wide band gap (3.37 eV) at room temperature and a large excitonic binding energy (60 meV) in comparison with GaN (28 meV) [1]. ZnO exhibits n-type semiconducting behavior due to native defects including Zn interstitials, oxygen vacancies, or hydrogen interstitials. This makes it difficult to understand the main effect of additional dopants in terms of the structure and optoelectric properties of ZnO. We successfully synthesized ZnO:In nanowires (NWs) with different indium doping concentration for comparison using gold nanoparticles as catalyst coated on Si substrates. A series of experiments revealed growth mechanism and analyzed main exciton behavior for the ZnO NWs with different indium doping concentrations.

Experiments

Results and Discussion

Conclusion