退火对Mn和N共掺杂的Zn_(0.88)Mn_(0.12)O:N薄膜特性的影响

Influence of annealing on the properties of Mn and N co-doped Zn_(0.88)Mn_(0.12)O:N films

以NH3为掺N源,采用电子束反应蒸发技术生长了Mn和N共掺杂的Zn1-xMnxO:N薄膜,生长温度为300℃,然后在O2气氛中400℃退火0.5h.X射线衍射测量表明,Zn0.88Mn0.12O(Mn掺杂)薄膜或Zn0.88Mn0.12O:N(Mn和N共掺杂)薄膜仍具有单一晶相纤锌矿结构,未检测到杂质相.与不掺N的Zn0.88Mn0.12O薄膜相比,Zn0.88Mn0.12O:N薄膜的(002)晶面衍射峰向小角度方向偏移且半高宽变宽.Hall效应测量结果显示,Zn0.88Mn0.12O:N薄膜由退火前的n型导电转变为退火后的p型导电.室温磁特性测量结果表明,虽然原生Zn0.88Mn0.12O:N薄膜呈铁磁性,但其饱和磁化强度Ms折算到每个Mn2+仅为约0.20μB,且稳定性不理想,在大气中放置30d后Ms降低到原来的3%左右.退火处理不仅使Zn0.88Mn0.12O:N薄膜的室温Ms增大到每个Mn2+约为0.70μB,且在大气中放置30d后其Ms几乎不变.分析了Zn0.88Mn0.12O:N薄膜的铁磁性起源及退火导致其铁磁性增强并稳定的机理.

Mn and N codoped ZnO（or Zn1-xMnxO：N） films were grown on Si（001） and quartz substrates via reactive electron beam evaporation in the NH3 atmosphere.The growth temperature was 300 ℃.The as-grown Zn0.88Mn0.12O：N film was cut into two pieces and one of them was then annealed in O2 atmosphere at 400 ℃ for 30 min.X-ray diffraction measurements reveal that Zn0.88Mn0.12O or Zn0.88Mn0.12O：N films have the single-phase wurtzite structure.The（002） diffraction peak of Zn0.88Mn0.12O：N film is located at a smaller angle and has a wider line width compared with that of Zn0.88Mn0.12O film.Hall measurement shows that the as-grown Zn0.88Mn0.12O：N film is the n-type and changes to p-type after annealing.DC magnetization analysis shows that the as-grown Zn0.88Mn0.12O：N films are ferromagnetic at room temperature（RT） but the ferromagnetism（FM） is weak and unstable.However,the FM of Zn0.88Mn0.12O：N film at RT is remarkably enhanced and its stability efficiently improved by annealing in O2 atmospher.The origin of FM of Zn0.88Mn0.12O：N film at RT,as well as the mechanisms of its FM enhancement and stability improvement by annealing are discussed.