退火气氛对ZnO∶Al薄膜光学、电学和微结构的影响

Effect of annealing atmosphere on optical,electrical properties and microstructure of ZnO∶Al films

研究退火气氛对ZnO∶Al(Al掺杂的ZnO,AZO)薄膜电学、光学、微结构和缺陷的影响。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、霍尔效应测试仪、紫外可见分光光度计、拉曼振动以及光致发光谱表征不同状态ZnO∶Al薄膜的晶体结构、微观形貌、电阻率、透射率、拉曼振动和光致发光特性。结果表明:空气退火后,AZO薄膜的载流子浓度从1.63×10^(20)cm^(−3)降低至7.1×10^(18)cm^(−3),光学禁带宽度从3.51 eV降低为3.37 eV,近红外透射率增加以及光致发光谱的带边发光峰位从3.49 eV红移至3.34 eV。氢气退火后AZO薄膜的载流子浓度升高至5.3×10^(20)cm^(−3),光学禁带宽度增加为3.78 eV,近红外透射率下降以及光致发光谱的带边发光峰强度增加了10倍,且发光峰的峰位蓝移至3.57 eV。此外,空气退火的ZnO∶Al薄膜观察到4级的拉曼多声子振动。

In this study,the effect of annealing atmosphere on the electrical properties,optical properties,microstructure and defects of ZnO∶Al films was investigated in detail.The crystallization,surface and fracture morphologies,electrical properties,resistivity,transmittance,Raman vibration and photoluminescence of ZnO∶Al films were characterized by SEM,XRD,Hall effect test instruments,ultraviolet-visible spectrophotometer,Raman spectra and PL spectra.The results show that after annealing in air atmosphere,the carrier concentration of AZO films decreases from 1.63×10^(20)cm^(−3)to 7.1×10^(18)cm^(−3),the optical band gap varies from 3.51 eV to 3.37 eV,the transmittance in NIR increased and the band edge emission in PL spectrum shifted from 3.49 eV to 3.34 eV.On the other hand,while the carrier concentration of AZO films annealing in H2 atmosphere was 5.3×10^(20)cm^(-3),the optical band gap increases to 3.78 eV,the transmittance in NIR decreases remarkably,the emission intensity of the band edge increases by more than 10 times and the band edge emission in PL spectrum shifts to 3.57 eV.Furthermore,the 4 order LO phonons are observed in ZnO:Al films annealed in air.