Influence of oxygen partial pressure on the microstructural and magnetic properties of Er-doped ZnO thin films

Wei-Bin Chen,Ren-Wei Zhou,Er-Wei Shi,Hong-Ming Chen,Xue-Chao Liu,Fei Li

doi:10.1063/1.4922141

Wei-Bin Chen, Ren-Wei Zhou + Show 4 more

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https://doi.org/10.1063/1.4922141

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Abstract

Er-doped ZnO thin films have been prepared by using inductively coupled plasma enhanced physical vapor deposition at different O2:Ar gas flow ratio (R = 0:30, 1:30, 1:15, 1:10 and 1:6). The influence of oxygen partial pressure on the structural, optical and magnetic properties was studied. It is found that an appropriate oxygen partial pressure (R=1:10) can produce the best crystalline quality with a maximum grain size. The internal strain, estimated by fitting the X-ray diffraction peaks, varied with oxygen partial pressure during growth. PL measurements show that plenty of defects, especially zinc vacancy, exist in Er-doped ZnO films. All the samples show room-temperature ferromagnetism. Importantly, the saturation magnetization exhibits similar dependency on oxygen partial pressure with the internal strain, which indicates that internal strain has an important effect on the magnetic properties of Er-doped ZnO thin films.

Highlights

In recent years, zinc oxide (ZnO)-based diluted magnetic semiconductors (DMSs) have attracted tremendous attention since the theoretical prediction of room temperature ferromagnetism property of ZnO was given by T
ZnO-based systems have been investigated extensively and room temperature ferromagnetism has been experimentally observed when 3d transition metal ions or 4 f rare earth ions are substituted for zinc ions in ZnO lattice.[2,3,4]
The researchers claimed that the ferromagnetism was due to the intrinsic properties of Er-doped ZnO films and could be interpreted by the bound magnetic polaron model (BMP)

Summary

INTRODUCTION

Zinc oxide (ZnO)-based diluted magnetic semiconductors (DMSs) have attracted tremendous attention since the theoretical prediction of room temperature ferromagnetism property of ZnO was given by T. There is only little experimental evidence[10,11] concerning on strain induced ferromagnetism in ZnO-based DMSs. As for rare earth metal doped ZnO, no research results related to this concern have been reported. It is necessary to perform in-depth investigation on Er-doped ZnO films to figure out the magnetic mechanism and strain effects on ferromagnetism. Based on our experimental results, the origin of room temperature ferromagnetism in Er-doped ZnO films grown with different PO2 has been discussed in detail. We specially focus on the influence of internal strain and defects on the ferromagnetism

EXPERIMENT

Structure properties

CONCLUSIONS