Suppression effect of silicon (Si) on Er3+ 1.54μm excitation in ZnO thin films

Bo Xu,Changdong Ma,Ranran Fan,Fei Lu

doi:10.1063/1.4961026

Abstract

We have investigated the photoluminescence (PL) characteristics of ZnO:Er thin films on Si (100) single crystal and SiO2-on-silicon (SiO2) substrates, synthesized by radio frequency magnetron sputtering. Rutherford backscattering/channeling spectrometry (RBS), X-ray diffraction (XRD) and atomic force microscope (AFM) were used to analyze the properties of thin films. The diffusion depth profiles of Si were determined by second ion mass spectrometry (SIMS). Infrared spectra were obtained from the spectrometer and related instruments. Compared with the results at room temperature (RT), PL (1.54μm) intensity increased when samples were annealed at 250°C and decreased when at 550°C. A new peak at 1.15μm from silicon (Si) appeared in 550°C samples. The Si dopants in ZnO film, either through the diffusion of Si from the substrate or ambient, directly absorbed the energy of pumping light and resulted in the suppression of Er3+ 1.54μm excitation. Furthermore, the energy transmission efficiency between Si and Er3+ was very low when compared with silicon nanocrystal (Si-NC). Both made the PL (1.54μm) intensity decrease. All the data in experiments proved the negative effects of Si dopants on PL at 1.54μm. And further research is going on.

Highlights

With the development of optical communication technology, Er3+-doped semiconductors have attracted considerable interest these years, due to the relevant photoluminescence (PL) at around 1.54μm (4I13/2 − 4I15/2) which coincides with the absorption minimum in silica-based fibers.[1,2] the special intra-4f shell structure of Er atoms imposes restrictions on the PL at 1.54μm, which is exactly the problem researchers spend so much effort on solving
The diffusion depth profiles of Si were determined by second ion mass spectrometry (SIMS)
The energy transmission efficiency between Si and Er3+ was very low when compared with silicon nanocrystal (Si-NC)

Summary

INTRODUCTION

With the development of optical communication technology, Er3+-doped semiconductors have attracted considerable interest these years, due to the relevant photoluminescence (PL) at around 1.54μm (4I13/2 − 4I15/2) which coincides with the absorption minimum in silica-based fibers.[1,2] the special intra-4f shell structure of Er atoms imposes restrictions on the PL at 1.54μm, which is exactly the problem researchers spend so much effort on solving. Researchers have studied a lot about Er ions’ PL (1.54μm) in ZnO thin films grown on Si substrate or quartz,[7,8,9,10,11,12,13,14,15,16,17,18] especially the enhancement of PL in films with Si-NC.[7,8,9,10,11,18] Most found Si-NC with specific size improved the efficiency of Er ions’ PL (1.54μm).[10,11] energy transfer to Er from host semiconductor or Si-NC has been investigated by many research groups,[3,13] the relation between. The introduction of Si was inevitable in ZnO films on Si and SiO2 substrates even at a low annealing temperature These results were very significant for the fabrication of Si-based devices and others where Er ions’ PL (1.54μm) was required

EXPERIMENTAL DETAILS

Characterization of thin films

Photoluminescence under different conditions

The energy transfer of PL

CONCLUSION