The Role of Nitrogen Dopants in ZnO Nanoparticle-Based Light Emitting Diodes.

Islam Mohammad Shafiqul,Jie Lin,Yasuhisa Fujita,Toshiyuki Yoshida,Raj Deep

doi:10.3390/nano12030358

Abstract

In this work, nitrogen-doped ZnO nanoparticles were synthesized in various conditions by the gas evaporation method with DC arc plasma. Nitrogen concentrations of 6.38 × 1018 cm−3 to 2.6 × 1019 cm−3 were obtained at a chamber pressure of 150 torr, using arc currents of 20 A to 70 A. The intensities of local vibrational modes at 275 cm−1 and 581 cm−1 in the Raman spectra of ZnO nanoparticles showed a dependency on the nitrogen concentration in the ZnO nanoparticles. The ratios of donor–acceptor pair and exciton emissions in the photoluminescence spectra of nitrogen-doped ZnO nanoparticles, and the electroluminescence of light-emitting diodes based on these nanoparticles, were nearly proportional to the Raman peak’s intensity at 275 cm−1. The results indicated that the nitrogen dopants in the ZnO nanoparticles were acting as an acceptor.

Highlights

IntroductionZnO is currently of great interest for the development of novel solid-state lighting devices
Results and Discussion with different chamber pressures ranging from 75 torr to 760 torr
−1 polar phonon modes E2 were observed at 438 cm, and the polar A1 (TO) and E1 second-order scattering feature at 332 cm−1 was attributed to the multi-phonon scattering (LO) optical modes appeared at 380 cm−1 and 584 cm−1, respectively [25]

Summary

Introduction

ZnO is currently of great interest for the development of novel solid-state lighting devices. ZnO light device development is the difficulty in fabricating p-type ZnO. Protocols that achieve reproducible and stable p-type ZnO have not been developed. The most reliable dopants for p-type ZnO are group V elements, such as phosphorus (P) [4], arsenic (As) [5], antimony (Sb) [6], and nitrogen (N) [7]. Nitrogen is the most suitable p-type dopant due to its atomic size being similar to that of oxygen. The behavior of nitrogen dopants in ZnO has been discussed by theoretical calculations, such as the ab initio electronic bandstructure method [8] and density functional theory [9]. Incorporating nitrogen dopants and co-dopants into ZnO has previously been reported [10,11,12]

Methods

Results

Conclusion